Gentlemen:

My 35w DDM HIDs have run fairly flawlessly the past few months... but only about 3 weeks ago, when the car is in motion, one of the HID units will not light up. Even when turning the lights on/off, that light won't work.

It's not until I've come to a full stop, turned off the car, then turn on the car, then the light does not light up - turns on.

At first I thought it was a voltage issue, so I put in a relay harness over the last weekend - so the lights get direct power from the battery. But same issue, when car is in motion, sometimes the light won't go on.

So ruling out power - do I just have a dying ballast?

I'm in the process of doing an OEM conversion and I having a similar problem. If the car is started and a xenon bulb won't ignite I pull back on the high beam stick and it fires right up. Then I let go of the stick. Not sure why this works. It might not work for you but it's worth a try.

I wonder if anyone else is having a similar issue.

I've definitely heard of people having trouble getting bulbs to ignite. Not sure what causes those issues for them and I wouldn't say my technique is something you should be satisfied with if it works but I thought I'd share.

For my situation the solution appears to be recoding the computer but I don't know if that's the answer to your problem.

Usually inadequate firing voltage. I installed DDM slim n my g/f's cougar that had OEM Bosch projectors and the output is excellent. Sometimes though, it takes a flick of the lights to get them to fire. I kept the factory harness in place and installed the entire HID kit inside the factory housing. I think I am getting some loss through the funky Ford connector which powers the LB, HB and Turns, all through one plug. It has been working with no issues for over a month now, so I am wondering if there was simply a break-in period.

~Phil

Except, my HIDs are running right off the battery with a relay harness.

So the issue began with power from the stock wiring and continues with a direct power source.

I got an email to the DDm guys... maybe they'll shed some light. Kinda scary having lights not turn on.

Except, my HIDs are running right off the battery with a relay harness.

So the issue began with power from the stock wiring and continues with a direct power source.

I got an email to the DDm guys... maybe they'll shed some light. Kinda scary having lights not turn on.

Just because you are running directly from the battery doesn't mean you can't have a power issue. Your battery may have sufficient power to start your vehicle, but if it is old and not working at full potential if might cause a problem. My jeep used to develop really strange transmission issues and after a very long and frustrating search for this intermittent problem, someone suggested i have my battery tested. turned out the battery was weakening in its old age and unable to supply full power to the tranny computer. it is possible your are experiencing a similar problem where the battery isn't able to supply the really high voltage needed to ignite an HID bulb

OK, when cold my battery is reading about 11v and car off. Is that low?
The battery is about 4 or 5 years old but cranks fine.

-Percy

With the battery fully charged and all electrical drains -- dome light, warning buzzer, etc. -- shut down, the voltage across the terminals should be 12.5 to 12.6 volts. If the battery is not completely charged, but still adequate to turn over the motor, you may see a voltage closer to 12.0 volts.

I would say your battery is nearing the end of its life especially when it is 4 to 5 years old. Is there any built up corrosion on the terminals?? If so clean them up, tighten the cables, and see if anything improves

Nick:

Thanks. No corrosion. it's totally clean.

But yeah I am only getting 11v when cold. I was checking it the other night and thought it was low. A quick call to my local BMW shop/pals confirmed that given it's over 5 years old, spend the last 3 years doing short commutes to work (think less than 4 miles a day)... the battery is probably spent.

Plus from what I have been reading, HID's can demand as much as 15amps to fire up... so if the battery is weak, that might be the culprit.

I initially didn't think of that because with e36 batteries, it either works or doesn't when it comes to starting. (Per my old 1996 M3).

Nick:

Thanks. No corrosion. it's totally clean.

But yeah I am only getting 11v when cold. I was checking it the other night and thought it was low. A quick call to my local BMW shop/pals confirmed that given it's over 5 years old, spend the last 3 years doing short commutes to work (think less than 4 miles a day)... the battery is probably spent.

Plus from what I have been reading, HID's can demand as much as 15amps to fire up... so if the battery is weak, that might be the culprit.

I initially didn't think of that because with e36 batteries, it either works or doesn't when it comes to starting. (Per my old 1996 M3).

I'm with your BMW buddies.. time for a new battery! Hope this solves your HID problems. Report back!

Try to get a voltage reading at the Hot terminal near the passenger side firewall, with the car running.
~Phil

MY car's voltage is reading only 11v cold and 12v to 13v at idle. So BOTH my battery and alternator aren't giving much juice to the car...

Ok, found out the hard way that my battery actually is putting out 12.77 volts and with car on, system is running the spec 13.7 volts...

:\

Ok back to square one. Not the battery. Not the alternator or voltage regulator... and maybe I can assume the HID system needs more like 14v+ to fire up?