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Thread: DSC Light On - How to Diagnose?

  1. #1
    Join Date
    Aug 2010
    Location
    Walnut Creek, CA
    Posts
    320
    My Cars
    2001 Z3 3.0 5MT

    DSC Light On - How to Diagnose?

    I'm up in San Fransisco for the holiday, 400 miles from home (L.A.), and since I've arrived, my car's DSC light has been on.

    Days prior to leaving, the DSC, ABS and BRAKE lights came on briefly, but they reset themselves.

    Scanning with my Peake tool did not give any error codes. I'm not worried about driving without DSC, as I won't be going through snow, but the bright orange light is quite annoying on a dark night drive. Plus I like to fix anything that breaks.

    Can anyone point me to any threads that cover this, or DIY's. Also, if anyone has experienced the same warning light, what was the cause?

    Also, upgraded my car to xenon (actually it was factory xenon but they were removed). Using Hella ballasts, Phillps D2S bulbs, DJ Auto clusters with Umnitza angel eyes (Orion LED version), and Bi-Xenon low beam.

    Didn't have time to take photos, but I will post some notes on the install and perhaps some photos later. The power for the LED rings will have to be changed in the future, but it's good for now.
    --
    2001 E36 Z3 3.0 5MT/Sport - back to 3 pedals, current FUN car, part time DD
    2000 E46 323iT 5AT/Sport - damned AT lost reverse, sold on an project car
    2009 E92 335i 6MT/Sport - escaped the PRC, sold to a good home, sorely missed
    2000 E39 528i 5MT/Sport - escaped the PRC, sold to a good home, missed


  2. #2
    Join Date
    May 2004
    Location
    Ohio
    Posts
    5,663
    My Cars
    540i/6, 02 Excursion Pow
    Check your wheel speed sensors at the module plug by using a DMM.

    http://www.bimmerfest.com/forums/sho...2&postcount=45

    If one checks bad, check it at the sensor to eliminate the wiring and replace sensor if necessary. If it test good, you need a module.
    http://www.eaceuroparts.com/catalog/product/426
    Last edited by jnyost; 04-17-2012 at 12:04 AM.
    "If everything seems under control, you're not going fast enough. - Mario Andretti"

  3. #3
    Join Date
    Jan 2007
    Location
    West Michigan
    Posts
    14,422
    My Cars
    98 540iA (Prd 11/97)
    Bluebee tackled this one...

    Why are my Traction Control (ASC/DSC) and Anti-Lock Brake (ABS) lights illuminated?
    Quote Originally Posted by bluebee View Post
    Here is my attempt at combining information for our ABS DIY repair writeup in a single post:
    Credit: Extensive leverage from other sources; as new information comes in, I will update this post as long as it will let me.
    Future: Maybe someone can put a copy of this in the DIY section after it's properly reviewed for mistakes.

    CLASSIC ABS FAILURE SYMPTOMS:
    - Most of the time, the problem is the ABS module or one of the 4 wheel speed sensors (& sometimes the brake pressure sensor)
    - In my 2002 BMW E39 DSC, three orange (warning) cluster display lights lit, ABS, Brake, & DSC
    - The 3 warning lights reset when the ignition is turned off, only to repeatedly reappear within minutes of normal driving
    - The fault is often intermittent leading you to falsely believe you've resolved the problem (proper diagnosis is important)
    - Sometimes the fault only appears when the engine is hot; other times only at speeds over 40 mph
    - Carsoft may erroneously show a rear speed sensor failure; but just replacing the speed sensor may make no difference.
    - All the work is in correct diagnosis of the problem[/URL]; parts replacement is trivial (from 1 to six bolts in a few minutes)
    - Hence, this BMW E39 ABS 3-warning light DIY will concentrate on understanding and diagnosis of the problem


    FALSE ALARM SANITY CHECK:

    If you recently drove on ice, a dynamometer, or on another very slippery surface, the car may just think the system has malfunctioned.
    - Driving a few miles on a regular surface should fix the problem.
    - Another fix is to slowly turn the steering wheel from completely left to completely right, then back again.
    - The warning lights will reset whenever you turn the car off (but go back on if the fault persists)
    BMW DESIGN PROBLEM:
    - The E39 ABS module was mounted too close to engine heat causing solder cracks & fried electronics
    - The 4 wheel sensors and wires are exposed to the elements and to shocks/vibration
    - The 3 steering yaw sensors seem pretty well protected from both hazards but they may need recalibration[/URL]
    Note: Apparently newer-model BMWs moved the ABS module further away from engine heat (need confirmation)
    FLOW CHART OF RECOMMENDED ACTIONS:
    0) Watch, for a few days, speedo, odometer, tripmeter, cruise control, transmission, & ABS/BRAKE/DSC light activity
    1) If ABS/BRAKE/DSC constantly comes back, test the 4 wheel sensor circuits from the ABS module connector
    2) If any sensor circuit shows up as bad, test that specific sensor itself at that wheel (otherwise skip to step 5)
    3) If the wheel sensor still shows up as bad, first remove, clean, grease, and re-install that sensor
    4) If it still tests bad, then replace the sensor
    ...
    5) If the sensors are good, test the ABS circuit with the Carsoft or Peake tools (or just assume a bad ABS module)
    6) If the Carsoft or Peake tools indicate a different sensor, test & replace that sensor (e.g., pressure, yaw, acceleration, etc.)
    7) Otherwise, assume your ABS module is the culprit (some say get your ABS module rebuilt anyway as it's going to go eventually)
    ...
    8) If your ABS module is suspected, you have only the following 5 options:
    - OPTION 0: You can do nothing and just not have ABS or DSC (not a good choice for anyone on this message board)
    - OPTION 1: You can attempt a 3-part rebuild yourself (unfortunately we don't have enough information to help you yet)
    - OPTION 2: You can send your module out for a rebuild (about 1/3 to 1/2 can be rebuilt but you'll have no speedo in the interim)
    - OPTION 3: You can buy a rebuilt module (you'll have to add approximately $100 for a VIN recode at the dealer)
    - OPTION 4: You can buy a brand new module (you'll again have to pay for a BMW dealership recoding to your VIN)
    Note: Most people don't deal with testing the other 15 items; they just opt for sending their ABS module out to be rebuilt, which isn't necessarily a bad thing because generally it is the ABS and even if it isn't, some argue it's not a bad idea to rebuild even a working ABS.
    READ THE SHOP MANUAL: ( http://www.bentleypublishers.com/isb...179/index.html )
    - For DSC pinouts, see Volume II, page ELE-15 of ABS/DSC controle module (A65) (2 sensors in the front and 2 in the rear)
    - For ASC pinouts, see Volume II, page ELE-21 of ABS/ASC controle module (A52) (only 1 sensor in the front and 1 in the rear)
    - For ABS/ASC/DSC system operation, see Volume I, page 300-12 (it's not all that useful though)
    - For ABS/ASC/DSC system components, see Volume I, page 340-26 (again, not all that useful if you have this)
    READ BMW MANUALS:
    - Bosch DSC part 1[/URL], Bosch DSC part II[/URL] (kindly supplied[/URL] by Max_VQ[/URL])
    READ THESE ARTICLES:
    - http://www.meeknet.co.uk/E38/ABS/Index.htm
    - http://forums.bimmerforums.com/forum...d.php?t=600452
    - http://forums.bimmerforums.com/forum....php?t=1230488
    - http://cparente.wordpress.com/2008/1...o-abs-problem/
    - http://www.bimmerfest.com/forums/sho...d.php?t=363554
    - http://www.bimmerfest.com/forums/sho...39#post4202239
    etc.
    UNDERSTAND DIGITAL MULTIMETER (DMM) TEST BASICS:
    - http://www.allaboutcircuits.com/vol_3/chpt_3/2.html

    GATHER SEAT-OF-THE-PANTS DATA:

    - Note exactly which warning indicators are lit (e.g., ABS & BRAKE & DSC)
    - Note whether cruise control is working or not (sometimes implicates the passenger-side rear sensor)
    - Note whether the speedometer (hence odometer & tripmeter) is working (sometimes implicates the driver-side rear sensor)
    - Note "free play", "dead spots", & "centering" of the steering wheel (sometimes implicates steering column sensors)
    - Note if normal ABS pulsation (ABS working) or skidding (ABS not working) when hard braking on sandy shoulders at 15 mph
    - Note if violent shudder[/URL] (ABS working) or screech (ABS not working) when firm braking on top of speed bumps at 5mph
    Note: It's not always just the sensor when the speedometer is also out with the 3 lights (the key is diagnosis)
    ACKNOWLEDGE ALL POSSIBLE (20) & MOST LIKELY (2) CULPRITS:
    • 1 BOSCH DC III Control Module 83 Pin (combined with the hydraulic unit in my E39, DSC III Bosch 5.7) <==COMMON CULPRIT!
    • 1 Hydraulic Unit (combined with the control module in my E39, DSC III Bosch 5.7)
    • Hydraulic Unit contains: 2 pre-charge solenoid valves
    • Hydraulic Unit contains: 2 changeover solenoid valves
    • Hydraulic Unit contains: 4 intake solenoid valves
    • Hydraulic Unit contains: 4 outlet solenoid valves
    • Hydraulic Unit contains: 1 return pump
    • 2 Front Wheel Speed Sensors (Active Hall Effect) in the steering knuckles, secured with two 4 mm allen bolts <==COMMON CULPRIT!
    • 2 Rear Wheel Speed Sensors (Active Hall Effect) in the rear wheel bearing carriers, secured with one 4 mm allen bolt <==COMMON CULPRIT!
    • 1 Hydraulic Pressure Sensor (attached to the front-brake hydraulic unit in my E39, DSC III Bosch 5.7) <==MY PROBLEM!
    • 1 Steering Angle Sensor (located in the bottom of the steering column, near the flexible coupling)
    • 1 Rotation Rate, aka Yaw Sensor (combined with the lateral-acceleration sensor in my E39, DSC III Bosch 5.7)
    • 1 Lateral Acceleration Sensor (combined with the yaw sensor in my E39, DSC III Bosch 5.7)
    • 1 DSC Switch (located below the radio in the cockpit)
    • 1 Hand Brake Switch (located on the hand brake assembly)
    • 1 Brake Switch (located on the brake-pedal assembly)
    • 1 Pre-Charging Pump
    • 1 Charging Piston (750iL only)
    PHOTOGRAPH OF THE MOST LIKELY CULPRITS:

    GATHER DESIRED TOOLS:
    - Print this DIY out, bring a pencil to mark down your readings, and a drink
    - Digital multi meter (DMM) with a diode-test capability & long, very narrow probes
    - About six inches of 20 AWG stiff wire (to attach to your DMM probes and to the female ABS connector)
    - A small piece of white or yellow tape so that you can label the positive stiff wire (to avoid confusion with the negative probe)
    - T20 six-point Torx bit in a 1/4" socket with a 6" extension for removing the ABS control module
    - 4mm allen wrench for removing the front wheel sensors
    - Torque wrench (see torque tables below) for replacing components
    - For rear sensors, a 10 mm socket, 8 mm socket, flat-head screwdriver, and needle-nose pliers might be required to remove trim.
    - 1/4-inch wide 6-inch long standard flathead screwdriver for removing ABS harness connector clip
    - CRC cleaner (or equivalent brake cleaner)
    - Staburags NBU 12/K or equivalent grease (for speed sensors and connections in the housings)

    GATHER OPTIONAL TOOLS:

    - (maybe) 10mm socket for removing air filter box (easier access for some E39 models)
    - Carsoft 6.5 or Peake Research or equivalent OBDII diagnostic scanner
    - Oscilloscope (look for millivolt square waves coming from powered sensors as the wheel turns)
    - Note: Carsoft 6.5 can't perform encoding, activation, or steering adjustments.
    - Note: Bad ABS modules often report erroneous indications of a bad RR sensor in the OBD scanner reports
    - Note: You must use new bolts for the ABS Control Module (according to the Bentleys)


    PRICE OEM PARTS:

    - Repair kit, control unit DSC, $1,120 + $112 (~10% tax) = $1,232 (often colloquially referred to as the "ABS control unit")
    - Wheel sensors, front, $134 x 2 = $268 + $27 (~10% tax) = $295 total (some suggested EAC tuning for wheel sensors)
    - Wheel sensors rear, $201 x 2 = = $402 + $40 (~10% tax) = $442 total (some suggested AutoHauz for wheel sensors)
    - Front brake pressure sensor, $111 + 10% tax = ~$125 (measures 0-250bars of front-brake pressure, outputs 0-5 volts)
    - Steering angle (yaw) sensors (in the steering wheel column or under driver's seat) ~$250 each (almost never needed)
    - Hydro unit, DSC, $2,003 x 1 + $200 (~10% tax) = $2,013 (this "hydro unit" behind the ABS control unit is almost never at fault)
    Note: If you replace the ABS module, you'll also need a $100 dealership recoding to your VIN & steering angles calibrated (apparently)
    PRICE REBUILDING OF YOUR ABS MODULE:
    - Module Masters ($105) http://www.modulemaster.com/en/abs/ate_bmw_asc.php
    - BBA Remanufacturing (8 days, $225) http://www.bba-reman.com
    - Auto & Truck Electronics ($105) EBAY seller's ID ATE1234, lifetime warranty, free shipping, quick turnaround
    - Note: A rebuild of your ABS unit won't require VIN coding, activation, or steering angle calibration
    PRICE A REBUILT ABS MODULE FROM ANOTHER VEHICLE:
    - For a rebuilt part, most suggest oembimmerparts.com[/URL], one of our sponsors[/URL], at about $450 + $45 tax = $500
    - Note: A rebuilt ABS unit from another vehicle requires a $100 dealership VIN recoding effort
    QUESTION: What happens if you don't code the VIN & check steering angles ... (does the car blow up?)
    CONSIDER FIXING IT YOURSELF (we need much more details to make this option viable):
    - Open up the module & look for broken solder joints which can be sucked and resoldered (take pictures)
    - Add point-to-point wiring where needed (we need more information to make this actionable)
    - Replace diodes and any other weak parts with more robust parts (again, not very useful unless we know exactly what)
    - Post before and after pictures so each of us can learn from the rest
    CHECK BMW ERROR CODES:
    - Locate the OBDII port, by law, in the cockpit, within 3 feet of the driver (above the driver's left knee in American BMWs)
    - Hook up Carsoft[/URL] or Peake diagnostic tools[/URL] to the OBDII port to determine any error codes
    - Cross reference Carsoft error codes[/URL] with the list of Bosch 5.7 error codes listed bellow (kindly supplied by Max_VQ[/URL])
    Note: Some say this check is of dubious value because a bad ABS module may show up as a bad rear sensor[/URL]; always test the sensor itself!
    BMW ABS/ASC Bosch[/URL] 5.7 Table of error codes:[/URL]
    5 Right Rear Wheel Speed Sensor
    6 Right Front Wheel Speed Sensor
    7 Front Left Wheel Speed Sensor
    14 Solenoid Valve Relay (check fuses 17 & 33)
    15 Pressure Sensor/Pump Error
    21 Module Memory Failure - ABS/ASC module is faulty
    23 Incorrect Coding - ABS/ASC module is faulty
    24 Wrong Impulse
    30 Left Rear Wheel Speed Sensor
    31 Open Right Rear Wheel Speed Sensor
    32 Open Right Front Wheel Speed Sensor
    33 Open Left Front Wheel Speed Sensor
    50 Right Front Outlet Valve - ABS/ASC module is faulty
    51 Left Rear Outlet Valve - ABS/ASC module is faulty
    54 Left Front Inlet Valve - ABS/ASC module is faulty
    55 ASC Intake Valve - ABS/ASC module is faulty
    58 Gear Box Control Unit (CAN bus error)
    59 DMER1 (CAN bus error)
    61 Steering Angle Sensor Identification
    66 Speed Sensor Voltage Supply
    67 Intermittent Interference
    75 Engine Speed Fault from DME
    81 Pressure Sensor
    82 Open Yaw Rate Sensor
    86 ASC Cut-off Valve Rear Axle
    88 Precharge Pump
    89 Low Voltage
    90 Temporary System Deactivation
    94 DDE Fault/Yaw rate sensor
    97 Steering Angle Sensor
    10 Brake Light Switch
    108 SN Control
    112 Open CAN to Instrument Cluster
    114 Pressure Sensor Offset
    117 Brake Light Switch Failure
    118 DME Status-Internal Error
    REMOVE ABS-MODULE CONNECTOR:
    - Facing the engine, slide the plastic retaining clip to the right with a 1/4 inch flathead screwdriver.
    - It is a plastic retaining clip, so do be careful not to break it; it slides over about 1 1/4 inches or so.
    - Once the clip is fully to the right, lift the electrical connector up
    - Notice the female (blue) connector with 42 holes (and very tiny lettering)
    - DO NOT STICK YOUR TEST LEAD INTO THE SQUARE HOLES!
    (Only put test leads into the larger rectangular holes next to the square holes.)

    NOTE ABS-MODULE PINOUT: (notice the test lead holes)
    - Each wheel sensor circuit has a set of two wires in the ABS connector (pinout[/URL] kindly supplied by 540iman[/URL])
    - ABS-connector pins 13,29 = Left rear wheel sensor (also affects speedometer & odometer & tripmeter)
    - ABS-connector pins 30,31 = Right rear wheel sensor (also affects cruise control)
    - ABS-connector pins 28,12 = Left front wheel sensor (some say it also acts as a steering angle sensor[/URL])
    - ABS-connector pins 15,16 = Right front wheel sensor (tells gearbox electronics how fast you're going[/URL])
    Note: These pinouts are in the same order of the diode action of each sensor (do not reverse these numbers)
    Note: Don't confuse with the brake pad wear sensor, which is only located on the front left & rear right wheel & which uses a black connector.
    Note: ASC cars have only two sensors, one on the front right and the other on the rear left wheel.

    UNDERSTAND WHEEL SPEED SENSORS:
    Note: The wheel speed sensors are two-wire hall effect transducers which send a digital square wave signal with a low of .75 volts and a high of 2.5 volts to the DSC control unit. Each sensor receives a well-regulated 8 volt power supply from the control module through one wire. The ground path for the sensor is through the second wire back to the control module. The signal is generated by a pulse wheel affecting the voltage flow through the hall element in the sensor. The pulse wheel is integrated into the wheel bearing assembly, behind the seal. This protects the trigger wheel from foreign substances which may affect the wheel speed signal.

    TEST WHEEL SENSOR CIRCUIT FROM THE ABS CONNECTOR
    (also checks wiring circuit):
    OPTIONAL: Jack car up (so that all four wheels can be spun to test voltage & resistance fluctuations of the hall-effect sensors)
    - Turn the car off and remove the key from the ignition.
    - TEST 1: Switch the DMM into the diode test position
    - Wrap a stiff 20AWG wire onto the ends of your DMM probe for sticking into ABS-connector pins
    - Label the positive 20AWG wire with white tape so that you won't get confused as you switch back and forth
    - Stick the ends of the wire into the appropriate female holes of the ABS connector (13-29, 30-31, 28-12, 15-16)
    - In one direction, you should see 1.7 to 1.8 volts (note the pinouts mentioned are in order, positive to negative)
    - In the other direction, you should see OL or some other infinite reading (open circuit)
    - TEST 2: Switch the DMM into resistance checking mode (optional)
    - You should see around 3.3 Mega ohms in one direction & approximately twice that in the other direction (but some say more[/URL])
    - TEST 3: If desired spin the wheel at about 1 revolution per second[/URL], by hand (the resistance should fluctuate as the wheel spins[/URL])
    - TEST 4: Switch the DMM into millivolt mode (optional) & again spin the tire & wheel assembly by hand (test-lead polarity won't matter)
    - You should read between 1 and 5 mV when you spin the hub[/URL] (no voltage implicate the sensor or circuit)
    - OPTIONAL TESTS BELOW REQUIRE FLYING LEADS WITH THE IGNITION SYSTEM ABS SYSTEM CONNECTED & POWERED UP:
    - TEST 5: Swith the DMM into the 10v and attach flying leads to the sensors with the power on
    - You should see the voltage going to the sensor and the return signal[/URL]
    - Expect a baseline voltage of about +5 to +12 volts depending on the ABS system (does anyone know this value?)
    - Expect that baseline voltage to the sensor to change (by how much?) as you spin the wheels
    - TEST 6: Hook an oscilloscope with "flying leads" to the ABS sensors (notice that the ABS system must be powered)
    - You should see nice clean square waves generated as you hand spin the wheels[/URL] at about 1 revolution per second.
    Note: The oscilliscope can detect problems [/URL]that can't easily be found with a DMM (A scope pattern for a wheel speed sensor should show a classic sine wave alternating current pattern that changes both in frequency and amplitude with wheel speed. As the wheel is turned faster, signal frequency and amplitude should both increase. Damaged or missing teeth on the sensor ring will show up as flat spots or gaps in the sine wave pattern. A bent axle or hub will produce an undulating pattern that changes as the strength of the sensor signal changes with every revolution. If the scope pattern produced by the sensor is flattened (diminished amplitude) or is erratic, it usually indicates a weak signal caused by an excessively wide air gap between the tip of the sensor and its ring, or a buildup of metallic debris on the end of the sensor. A weak signal can also be caused by internal resistance in the sensor or its wiring circuit, or loose or corroded wiring connectors.)

    INTERPRET DIODE-TEST RESULTS:
    - If the DMM, in diode mode, reads infinity ("OL") in both directions, you've got a bad sensor or circuit
    - If the DMM, in resistance mode, reads much greater than 7Mohms, you've got a bad sensor or circuit
    - If all 4 sensors read OK, it's most likely the ABS control unit.
    - If you think you found two bad sensors, you probably messed up.
    - Rarely is the cause due to bad steering angle (yaw/lew) sensors
    - Rarely is the cause due to a bad hydro unit
    - The problem is almost always a wheel rotation sensor or the ABS control unit
    ACTUAL RESULTS ON MY 2002 E39 THIS MEMORIAL DAY WEEKEND:

    DOUBLECHECK WHEEL SENSORS AT THE WHEEL:
    Note: You can run this test w/o removing the wheel but access to the sensor connector is easier with the wheels off the E39
    - If one or more sensor circuits test bad in any of the three tests above ... then ...
    - Locate the sensor blue connector in the rear of each front wheel well by turning the front wheels
    - Easiest to first locate the sensor (bolted on the wheel carrier near the hub) and trace its wire back to a black plastic hinged box housing
    - Open the locked hinged plastic rectangular black box with a small flathead screwdriver
    - Locate the blue wheel sensor connector (next to a black brake wear sensor connector)
    - Pull the blue wheel sensor connector out of the box and disconnect the two sides
    - Re-check the sensor there with the diode function of the DMM

    CHECK WHEEL SENSORS OFF THE VEHICLE:
    - If any sensor still checks bad, pull the sensor off the vehicle for a closer inspection
    - Chock wheels and jack E39 BMW and jack stand at the 4 jack pad locations
    - Remove 4mm allen head bolts to sensor retention screw (two retaining bolts for fronts, 1 bolt for the rears)
    - Pull wheel sensor out of hub assembly, straight up.
    - Clean with CRC electronic cleaner
    - Check with DMM diode-test meter as before
    - Grease with Staburags NBU 12/K or equivalent grease
    - Replace sensor back into hub assembly, snug tighten to 6 foot pounds
    - Replace rear wheel, tighten to 82 to 96 foot pounds
    Note: You might wish to swap sensors on the same axle when replacing so as to obtain further diagnostic information should an anomaly occur.
    Note: Here is a picture of a dirty and cleaned sensor (magnetic particle buildup[/URL])


    TEST BRAKE PRESSURE SENSOR (aka HYDRAULIC UNIT PRESSURE SENSOR):
    - This test procedure kindly suggested by Max_VQ:
    - Given 250 bar = 3,626 psi, and given 0-5 volts linear proportional output, 3,626 psi/ 5v = 725.2 psi/volt or 1.3 mV per psi.
    - With the ignition on, measure the voltage on the pressure sensor while someone is pressing hard on the brake pedal
    - My guess is that should create about 3,000 psi of force and should show around 4.13 volts.
    - At rest it should show very close to 0 volts
    Note: The front-brake pressure sensor provides a 0-5 volt linear voltage signal to the DSC III control module which is proportionate to how hard the driver is pressing on the brake pedal, from zero to 250 bars (3,626 psi), spanning (a) no braking, to (b) partial braking, and to (c) near-ABS-regulation state braking. This brake pressure sensor has three pins (a) power, (b) ground and (c) the 0-5 volt proportionate signal.
    Note: By way of comparison, the Corvette also has a brake pressure sensor to indicate how hard the brakes are being applied; it monitors pressure from 0 to 2000psi generating a corresponding signal of 0.20 volts to 4.80 volts[/URL].
    LOCATION OF FRONT-BRAKE PRESSURE SENSOR:
    • DSC III 5.3 (740i/iL and 540i) - The brake pressure sensor is located in the charge pump assembly.
    • DSC III 5.3 (750iL) - The sensor is located on the charge piston unit.
    • DSC III 5.7 (ALL) - The sensor is located on the hydraulic unit on my 2002 E39.

    TEST ROTATION RATE & LATERAL ACCELERATION SENSOR:
    - We do not yet have a test for this sensor; a description of operation is all we have at the moment (please suggest a test procedure so all benefit)
    - On Bosch DSC III (Bosch 5.7) the Rotation Rate sensor (yaw) and the Lateral Acceleration sensor have been combined into one unit located under the drivers seat under the carpet
    - The degree of rotation rate (yaw) transducer outputs a reference signal of 2.5 volts and a linear voltage of 0.7 to 4.3 volts
    - The lateral acceleration output signal should be 1.7 volts while the car is sitting still on a flat surface corresponding to 0 G side forces.
    - The lateral acceleration transducer outputs a linear voltage of 0.5 to 4.5 volts corresponding to a G-Force range of -1.5 to +3.5 G side forces depending on the motion of a fixed capacitor plate relative to a floating capacitor plate.

    TEST STEERING ANGLE SENSOR:
    - We don't yet know how to test the steering-angle sensor (please advise)
    Note: The steering angle sensor, mounted at the bottom of the steering column near the flexible coupling, utilizes two potentiometers to determine the steering angle and the rate of steering angle change, which are are the two raw signals the CAN bus microprocessor utilizes to create the steering angle signal for broadcast over the CAN bus. The DSC III logic compares the stored plausibility of the steering angle sensor against other DSC III inputs (front wheel speeds, rotation rate and lateral acceleration sensors).
    STEERING ANGLE SENSOR:


    REMOVE ABS MODULE:
    - Remove the six T20 Torx screws holding the ABS module to the hydro unit
    - Pull the ABS module straight out towards the passenger side headlight.
    - Cover the hydro unit with aluminum foil to protect it from the elements
    - You can drive the car but you won't have a speedometer or odometer
    - Use a portable GPS unit with a speed display as your temporary speedometer
    - You may not have cruise control (need to test this)
    - Of course, you won't have ABS either but you didn't have that anyway

    HINTS TO HELP OTHERS:
    - Consider taking apart your ABS module and posting before rebuild and after rebuild pictures
    - Consider paying rebuilders the extra $10 to return ABS modules that failed[/URL] (so you can take it apart & post pictures)
    - Consider selling your old module to the rebuilders if you buy a new or rebuilt ABS module from another vehicle
    - A portable GPS unit doubles as a speedometer in the interim while your ABS module is being rebuilt
    REINSTALL ABS MODULE:
    - Note: There is a gasket attached to the new unit.
    - Carefully place the new module over the control actuators.
    - Loosely replace the six new T20 Torx screws included with the new module.
    - Tighten snug tight, and then a little more to seat the gasket.
    - Reposition the ABS electrical connector
    - Press down on the ABS connector while pushing the retaining clip to the left
    - Reassemble the Air Filter box & MAF (if it was disassembled for Torx access).

    INITIALIZE ABS MODULES:

    - Note: This step is only necessary if you installed an ABS module that wasn't originally in the car in the first place
    - Take the E39 to an Indy to encode the VIN (I'm not sure what happens if you don't do this)
    - Take the E39 to an Indy to check and adjust the steering angle (I'm not sure why)
    - Some say the steering angle sensor may have to be recalibrated when you put on a remanufactured or new ABS module.
    TORQUE TABLE:
    - 4mm wheel sensor bolts (two each for the front sensors, 1 each for the rear sensors) = 6 foot pounds
    - Combination lateral acceleration/rotational rate sensor (under driver seat) = 6 foot pounds
    - DSC bolts to the hydraulic unit (new bolts only) = 26 inch pounds
    - Hydraulic unit to body = 6 foot pounds
    - Hydraulic unit mounting bracket = 6 foot pounds
    - Brake lines to hydraulic unit = 13 foot pounds
    - Wheel lug nuts = 82 to 96 foot pounds
    DIAGRAM OF THE 2002 E39 DSC III BOSCH 5.7 SYSTEM:

    USE THIS CHART TO DETERMINE WHICH ABS SYSTEM YOU HAVE:

    Note: This ABS repair thread was compiled from scores of sources; special credit goes to many people, especially 540iman[/URL], BlackBMWs[/URL], Max_VQ[/URL], Edgy36-39[/URL], and others.

  4. #4
    Join Date
    Aug 2010
    Location
    Walnut Creek, CA
    Posts
    320
    My Cars
    2001 Z3 3.0 5MT
    WOW! That is an amazing DIY! Seems I have a lot of diagnosing to do.

    DSC light is still lit, no other warning lights, ABS is working.
    --
    2001 E36 Z3 3.0 5MT/Sport - back to 3 pedals, current FUN car, part time DD
    2000 E46 323iT 5AT/Sport - damned AT lost reverse, sold on an project car
    2009 E92 335i 6MT/Sport - escaped the PRC, sold to a good home, sorely missed
    2000 E39 528i 5MT/Sport - escaped the PRC, sold to a good home, missed


  5. #5
    Join Date
    Sep 2009
    Location
    San Antonio, TX
    Posts
    192
    My Cars
    2002 540i Sport
    Yeah, that DIY saved me some real headaches. I had the nightmarish scenerio of DSC/ABS lights and Failsafe Trans problem. I ran through every scenerio and came up with a dirty wheel speed sensor. Every repair place wanted a LEAST $1300 to fix my module.

    This is a very good walkthrough showing the best way to troubleshoot your ABS problems.

    Clay

  6. #6
    Join Date
    Aug 2010
    Location
    Walnut Creek, CA
    Posts
    320
    My Cars
    2001 Z3 3.0 5MT
    DSC is definitely not working. I hadn't realized up to now just how easily even a 528i can spin the back wheels.
    --
    2001 E36 Z3 3.0 5MT/Sport - back to 3 pedals, current FUN car, part time DD
    2000 E46 323iT 5AT/Sport - damned AT lost reverse, sold on an project car
    2009 E92 335i 6MT/Sport - escaped the PRC, sold to a good home, sorely missed
    2000 E39 528i 5MT/Sport - escaped the PRC, sold to a good home, missed


  7. #7
    Join Date
    Jan 2004
    Location
    Elm Grove Farm, NC
    Posts
    2,777
    My Cars
    too many
    Is bluebee on BFc?

    My 2000 528iT has a DSC light on, the code according to the scanner is "(58) 88 pre-charging pump"

    Just curious if bluebee had the same code- since he says (I think) that the pressure sensor on his ABS pump was the culprit to his DSC light coming on.


    FWIW, I had my ABS Module "rebuilt" by ATE about 1.5 years ago, it was fine for a while, but now I think it may be the problem again.

  8. #8
    Join Date
    Sep 2006
    Location
    New York
    Posts
    5,563
    My Cars
    2003 525i
    Quote Originally Posted by Rigmaster View Post
    Is bluebee on BFc?

    My 2000 528iT has a DSC light on, the code according to the scanner is "(58) 88 pre-charging pump"

    Just curious if bluebee had the same code- since he says (I think) that the pressure sensor on his ABS pump was the culprit to his DSC light coming on.


    FWIW, I had my ABS Module "rebuilt" by ATE about 1.5 years ago, it was fine for a while, but now I think it may be the problem again.
    I had the same code "Pre-Charging Pump". Here is my tale:

    http://forums.bimmerforums.com/forum....php?t=1154808

    Read it all.

    cliffs = buy a NEW ABS MODULE from www.eactuning.com and have it installed/programmed by your local BMW dealer.
    "I'd smash that (Jennifer Connelly) like a failed coup in sub-Saharan Africa."
    ~Macktheknife in my epic Jennifer Connelly OT Thread

  9. #9
    Join Date
    Jan 2009
    Location
    Chicago South IL
    Posts
    4,791
    My Cars
    2003 530i Sport
    it maybe Steering Angel Sensor issue
    It affects DSC
    happens with new suspension/wheels/alignment
    this sensor should be recalibrated
    search
    Last edited by champaign777; 01-24-2011 at 04:44 PM.

  10. #10
    Join Date
    Jan 2004
    Location
    Elm Grove Farm, NC
    Posts
    2,777
    My Cars
    too many
    Quote Originally Posted by bimmerfiver View Post
    I had the same code "Pre-Charging Pump". Here is my tale:

    http://forums.bimmerforums.com/forum....php?t=1154808

    Read it all.

    cliffs = buy a NEW ABS MODULE from www.eactuning.com and have it installed/programmed by your local BMW dealer.

    Hi and thanks for the link and advice.

    I had read that thread previously, and I am 95% sure I need a new ABS module, BUT after reading the excellent DIY posted at the top of this thread by James (originally by bluebee), I'm wanting to make sure it's not something else before I plunk down my $5-600 for a new module from EAC.


    Bluebee says that his problem was a bad pressure sensor in the ABS pump, just trying to confirm if he had the "Pre-charging pump" error before this or not, and what the test results were that helped him decide it was the pressure sensor and not the pump or the ABS module.

    Quote Originally Posted by champaign777 View Post
    it maybe Steering Angel Sensor issue
    It affects DSC
    happens with new suspension/wheels/alignment
    this sensor should be recalibrated
    search
    Don't think it's steering angle sensor issue, I haven't done any new wheels or suspension or alignment.

    And, thanks- but I have searched, ALOT.
    Last edited by Rigmaster; 01-24-2011 at 04:46 PM. Reason: Automerged Doublepost

  11. #11
    Join Date
    Jan 2007
    Location
    Berkley MI
    Posts
    1,458
    My Cars
    2009 C350
    Can the OP or Rigmaster update this with their solution? I'm running into the exact same issue with a lit DSC light and Precharge pump error. It would be nice once you've resolved the issue to update the outcome so other members that run into the same issue, know what to do.

  12. #12
    Join Date
    Aug 2010
    Location
    Walnut Creek, CA
    Posts
    320
    My Cars
    2001 Z3 3.0 5MT
    Believe it or not the problem went away. I think it was low battery voltage. I had bought a good charger to bring a battery back to life on another car I had to sell. Then I started using it on the 528. Charging once a week seems to keep the battery in good condition.

    Can be 100% sure of this diagnosis, but I tried the other diagnostics and could not find anything wrong, and not long after I started charging the battery the DSC light went off.

    Hope this helps.
    --
    2001 E36 Z3 3.0 5MT/Sport - back to 3 pedals, current FUN car, part time DD
    2000 E46 323iT 5AT/Sport - damned AT lost reverse, sold on an project car
    2009 E92 335i 6MT/Sport - escaped the PRC, sold to a good home, sorely missed
    2000 E39 528i 5MT/Sport - escaped the PRC, sold to a good home, missed


  13. #13
    Join Date
    Apr 2011
    Location
    Mcloud, Oklahoma
    Posts
    3,098
    My Cars
    '99 323is, '00 323i 528i
    "pre-charge pump" and "pressure sensor" errors are two totally different things.
    (both can be caused by the ABS module though)

    The "pre-charge" pump is the one located on the intake side of the engine under the cabin air filter assembly on the frame rail. Don't confuse this with the pump mounted on the aluminum block where the ABS module mounts.

    First thing I would do is apply 12v directly to the pre-charge pump and see if it comes on.
    This could be done directly at the pump... positive wire has green on it, negative wire has brown on it if I recall.
    Or
    via pins 3&4 (iirc) on the ABS module harness connector. Be cautious of positive and negative....pin 3 is positive, pin 4 is negative. (look at harness connector pics in previous posts above)

    If the pump runs....then it is most likely the module itself. The wires inside that control the voltage going to the pump are the ones typical of getting broken due to vibration.

    If you can NOT get the pump to run directly, then it could very well be bad.

    And if trying to run the pump functions with INPA, DIS, or anything like that.... it will ONLY work if the MODULE is good. (the module is what sends power directly to the pump)
    So if the pump does not run via the test programs, then you still need to check the pump itself by applying voltage directly to it. Because you could still have a bad module not allowing it to run.


    Not a true DIY, but hope this might point some of ya'll in the right diagnostic direction.
    Attached Images Attached Images

  14. #14
    Join Date
    Jan 2004
    Location
    Elm Grove Farm, NC
    Posts
    2,777
    My Cars
    too many
    Quote Originally Posted by Vipsa View Post
    Can the OP or Rigmaster update this with their solution? I'm running into the exact same issue with a lit DSC light and Precharge pump error. It would be nice once you've resolved the issue to update the outcome so other members that run into the same issue, know what to do.
    I ended up sending my module back to ATE to be repaired again, under warranty. Cost me ~$20 in shipping ($10 each way), they repaired it and I reinstalled it several months ago and it's been fine ever since.

    No idea what they did, but fingers crossed that it continues to work for a few more years.


    For the record, ATE is not the most responsive in terms of customer service, but they've always come through for me and honored their warranty without any trouble. I found them on Ebay, and I think they charged me $129 to rebuild my ABS module, which included return shipping to me (the first time).

  15. #15
    Join Date
    Jan 2007
    Location
    Berkley MI
    Posts
    1,458
    My Cars
    2009 C350
    Awesome. Thanks for all the updates. Now, when I do an Activate option in INPA I can hear what seems to be a buzzing sound. Does that mean that the pump is running? How would I know if the pump is good even if I applied 12v to it?

  16. #16
    Join Date
    Jan 2007
    Location
    West Michigan
    Posts
    14,422
    My Cars
    98 540iA (Prd 11/97)
    Quote Originally Posted by Rigmaster View Post
    Is bluebee on BFc?
    Bluebee is a member on the Fest, and he is a "she".

  17. #17
    Join Date
    Jun 2008
    Location
    Phoenix, AZ
    Posts
    267
    My Cars
    '04 325i, '01 525iT
    I just had the same issue - DSC light on only (no ABS or Brake) and I had the precharge pump code. ABS worked fine. I sent my module off to BBA Reman and it came back today. No more DSC light. My light was on for a few months and with winter coming up I decided I couldn't put it off any longer. It was $225 to repair it and they turned it around in less than two days. Granted, it's only been a few hours, but I'm giving them the thumbs up.
    Last edited by bschmidt25; 12-13-2011 at 02:14 AM.

  18. #18
    Join Date
    Aug 2009
    Location
    Lebanon - Beirrut
    Posts
    28
    My Cars
    2002 530i
    Hey all, just want to share my experience,

    Couple of days ago I had the dsc light on.. No abs or brake faults. Surprisingly the solution was pretty simple.. Turns out the steering angle sensor needs re-calibration.. It's a 10 mins process.. (I don't remember what tool the shop used.. I think it's a GT1 scanner) I thought at first that the sensor will re-calibrate when you turn the steering wheel all the way from side to side..

    Just FYI I had low battery voltage error codes as well.. (had a small electrical incident while testing the new sound system). The shop suggested that the sensor was out of sync due to the low voltage since I didn't do any wheel alignment or suspension modifications lately..

  19. #19
    Join Date
    Dec 2015
    Location
    Drammen, Norway
    Posts
    7
    My Cars
    2000 BMW 728i (E38)
    Thank you all for your very useful posts from almost five years ago. There is still a need for them, as you now see :-)
    Sorry that my reply overlaps both the E39 and E38.

    I have been testing the pins in the blue ABS connector on my 02/2000 BMW 728i today, as all three yellow DSC/Brake/ABS lights are now permanently on.
    The ABS control unit was overhauled a few years ago, so I presume this is not the culprit...for now.
    What puzzles me, are the results from my multimeter:
    Left Rear, pin 13+ and 29- : Diode mode "OL" / Resistance 0
    Right Rear, pin 30+ and 31- : Diode mode "OL" / Resistance 0
    Left Front, pin 28+ and 12- : Diode mode "OL" / Resistance 0
    Right Front, pin 15+ and 16- : Diode mode 0,041V / Resistance 97,6 Ohm (not Mohm)

    Have any of you experienced this puzzling result or similar?
    Could it indicate a short somewhere?
    It would be interesting to know what all the remaining pins are for, just to make sure the right ones are being tested. However, I have not been able to find this info anywhere, and my BMW TIS/ETM/WDS CDs are too old to be read...ha-ha! :-D
    I am leaning towards spending tomorrow checking for wiring harness damage, as mentioned HERE

    Have a nice weekend! :-)
    Tord C. Freuchen.

  20. #20
    Join Date
    Nov 2009
    Location
    USA
    Posts
    9
    My Cars
    2002 530I
    Awesome tutorial. Thank you for putting this together. I am currently dealing with the DSC light on an E60. Looks like I have a lot of troubleshooting to do.

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