Low Beam Circuit Fault

Hey All, I had recently replaced the front headlights of my 95 M3 and all was working fine for a while. Then all of the sudden, I get the "CHECK" light come on about my low beam circuit fault. I pull over to look, and sure enough my low beams are still working fine. I then flick on the high beams, they work fine. I switch back to low beams, no issues. Then my brake light circuit fault comes on, but the brake lights work fine. I know how to solve the brake light circuit fault issue by just replacing the switch, but what would one do to eliminate the low beam circuit fault?

And yes, I do have fog lights on my car as well, in case anyone wants to know, and they work fine. But I don't know if that will do anything to cause this issue.

Are you running the oem lights, or are have you installed aftermarket lights? Such as angel eyes?

yeah if you install HIDs the car will think the bulb is out

These are OEM lights, as far as I can tell. I will check again when I get home. I got them used from a friend off the bimmer forums. No angel eyes or anything, it was as OEM as it could be. Again, it was working fine up until this past weekend to be more descriptive. I installed it a couple months ago. Now I will add that it has clear turn signal lights. I am going to switch them back to amber. Could that be an issue?

The corners have nothing to do with a low beam failure.

Oh dear, I wonder if this could be related to the trunk wiring issue, where the wires get all brittle then start contacting with each other and cause all sorts of electrical faults. But the brake lights work fine. I don't see much flickering with the trunk light when I open the trunk. I dunno, this is definitely interesting. My tinkering urges are getting tickled. Tee hee hee!

Anybody else think this might be related to the trunk wiring harness? http://forums.bimmerforums.com/forum...ad.php?t=79896

Originally Posted by hnaz

Oh dear, I wonder if this could be related to the trunk wiring issue, where the wires get all brittle then start contacting with each other and cause all sorts of electrical faults. But the brake lights work fine. I don't see much flickering with the trunk light when I open the trunk. I dunno, this is definitely interesting. My tinkering urges are getting tickled. Tee hee hee!

Anybody else think this might be related to the trunk wiring harness? http://forums.bimmerforums.com/forum...ad.php?t=79896

Just open the trunk and pull the insulation down past the tight bend. You will be able to see wires were the insulation wore though and are contacting.

Excepting that Low Beam is is front of car only feature, and front and rear lighting are on completely different circuits and would have zero effect on each other...

Just my $0.02.

Originally Posted by jonesin

Excepting that Low Beam is is front of car only feature, and front and rear lighting are on completely different circuits and would have zero effect on each other...

Just my $0.02.

That is true, but I wonder if short circuits can travel through the electrical system of the car. I know the OBC is connected to all sides of the car and maybe it is receiving a fault from the trunk wiring and is going haywire?

Just trying to brainstorm this and gathering people's inputs before I tear the car apart. I know I will definitely be replacing the trunk wiring harness for both my 318 and M3 in the near future. I just want to be about 90% sure what the problem is so I know how to fix it.

Right now I am thinking about replacing the fuses, cleaning up the contact points of the harness that connects to the bulbs and even coat the connection with dielectric grease, and even replacing the bulbs themselves (since they are mismatched with 9005 and 9006 - Left, 9007 and 9005 - Right).

That would be my guess as to your issue. 9006 are your low beam bulbs. If one is a 9007 it is entirely possible that it has different resistances that the car isn't expecting, thus triggering the failure.

But let me stress again the brake light fault comes on while the regular low beams are on. That's what is making things confusing. There might be a short somewhere that is tripping the OBC.

After I swaped to my hids I had the same issue I found that since the hids have a lower amp draw it trips the computer

Sent from my SGH-T769 using Bimmer App

just drive in the daytime...




df

Well, I didn't get a chance to do anything this weekend, but I did notice that after cleaning up the contacts going to the bulbs of the car, the low beam fault went away briefly only to come back when I pressed on the brakes. I pull over, turn off the car, turn it back on, turn on the headlights, low beam circuit failure back along with the brake light circuit failure. Not using HIDs either. I think tonight I am just going to stop by Advanced Auto and buy the bulbs.

Anyone know what the factory recommends for low beam and high beam bulbs? Since I got an assortment of bulbs on my car, I figure I ask now so I can get the proper bulbs this evening.

-Harry

9006 for the low beams.
9005 for the high beams.

Sent from my U8651T using Bimmer App

Thanks jonesin.

Alright, I replaced the bulbs, still getting the error. Low Beam Circuit Fault. Then as soon as I hit the brakes, brake light circuit fault. There has to be a short going on somewhere. But if the lights are off, no brake light circuit fault.

I think I am going to replace the brake light switch and the relay/fuse for the front headlights. If this doesn't work... I am at a loss.

Take a look through this thread:

http://forums.bimmerforums.com/forum...d.php?t=682355

Hey Jonesin, I appreciate the link. I have to check my wiring in the trunk. I almost forgot about that. I felt the wires through the insulation and it did feel a bit rough in there. So I think when I get time, I will just get a razor blade and cut it open and go to town on any broken wires and solder them back together.

But it still isn't answering the problem with the low beam circuit failure. One guy on the bimmerforums posted this (I have the same thread over there, to reach a larger crowd and some ideas):

The Brake light error is the switch. Take it off the table.

If your headlamps are mismatched, this _could_ be an issue, although I'm not sure how. Why have mismatched headlamps, that's the question. I always replace headlamps in pairs.

The math involved is pretty simple. A known resistance at a certain voltage will have a calculated draw of . The is an expected value based on voltage and resistance, if is not the expected value, then the fault is generated. I don't know what the resistance of a headlamp is supposed to be, but the engineers know. They designed a circuit in the Check Control Module (CCM) that either passes current or not depending on the value of -- if this value is high, then the low beam lamps are deemed to be malfunctioning. Current should flow through the headlamps, not through the circuits of the CCM.

If you are happy to walk around to the front of the car to see if the headlighs work or not, then you can bypass the CCM and kill that display for ever.

The CCM is located all of the way to the left of the dasboard, completely to the top and fully to the front by the firewall. If there was a window where the VIN plate is located at the base of the windshield, that window would let you look at the CCM.

You must remove the CCM from the driver's footwell. I found that when I removed the light switch and vent ducting, I could see where I was poking the socket wrench to get the nuts off that hold the CCM in place. The CCM has a hidden 10mm nut and an exposed one.

Once the CCM is removed, set it aside. You don't care about it, the wires are what you are interested in.

There is a YEL/GRY wire on Pin 8, and YEL/RED wire on Pin 15 that go IN to the CCM. There is a YEL/BLU (or YEL/GRN) wire coming OUT of the CCM on both pins 12 and 13.

You want to cut all 4 of these wires, then connect the wire that was on Pin 8 to the wire that was on Pin 12, and the wire that was on Pin 15 to the wire that was on Pin 13.

Put everything back together. The CCM will be bypassed, and the Low Beam Failure error will never appear again.

Do not obsess over the wire colors being described as ONE or THE OTHER. "OR" just means that the factory switched wire colors for some reason. The important thing is that Pins 8 and 15 are the voltage feed into the CCM, Pins 12 and 13 are the voltages out of the CCM that go to the headlamps. You want to connect the wire from Pin 8 to the wire from Pin 12, and the wire from Pin 15 to the wire from Pin 13.

What do you think?

I will add, I noticed that the headlights did flicker a couple times when I went over those school zone rumble strips. I pulled over at a gas station and checked out the connection to the new bulbs, and things were fine. When the headlights are off, the brake light circuit fault goes away. This is really making me wonder.

Only thing I haven't done yet is replace the fuse and relay. So that is next on the plate. If this does not work, I gotta bust out the OHM meter and see what's going on. Do you think a problem like this could be as simple as looking at the dial that turns on the headlights? Maybe there isn't a contact being made or it is a weak contact? Dielectric grease perhaps? I'm running out of ideas.

Are you having weird responses when you turn the headlight dial? If not, I doubt that's the issue. I wonder, are you sure the headlights themselves are OEM? I would begin by cleaning the connections at the lights and following your wiring back.

If they turn out to not be OEM, ddm makes a low beam failure fix thingy for their hid sets. You might look at that, it may help. That being said, I have these and think I put them in wrong because I still get the check light for it. I'm just too lazy to fight the housing back out to fix it.

Sent from my SCH-I405 using Bimmer App

Originally Posted by bimmerbarbie

Are you having weird responses when you turn the headlight dial? If not, I doubt that's the issue. I wonder, are you sure the headlights themselves are OEM? I would begin by cleaning the connections at the lights and following your wiring back.

If they turn out to not be OEM, ddm makes a low beam failure fix thingy for their hid sets. You might look at that, it may help. That being said, I have these and think I put them in wrong because I still get the check light for it. I'm just too lazy to fight the housing back out to fix it.

Sent from my SCH-I405 using Bimmer App

the DDM head light failure eliminators do not work I have a set and I still get the failure notice.

From what I've seen they work about 2/3 of the time. The remainder are just ... ... well, there is no polite civilian equivalent for that term... Hmm.

Originally Posted by bimmerbarbie

Are you having weird responses when you turn the headlight dial? If not, I doubt that's the issue. I wonder, are you sure the headlights themselves are OEM? I would begin by cleaning the connections at the lights and following your wiring back.

If they turn out to not be OEM, ddm makes a low beam failure fix thingy for their hid sets. You might look at that, it may help. That being said, I have these and think I put them in wrong because I still get the check light for it. I'm just too lazy to fight the housing back out to fix it.

Sent from my SCH-I405 using Bimmer App

Actually, I am very glad you asked this and I called the previous owner. The lights themselves, the original lights that were on the car were modified for HIDs and LEDs. He removed them and installed OEM headlights he got second hand from a junk yard. But when I got them, the OEM headlights he installed were cracked on one side, and the other side had a broke bracket so the corner light would not be able to seat properly. It would hang in limbo and fall off as soon as you hit a bump.

So with that said, I rushed back down to my car and saw something interesting... it looks like there are extra leads there, but it is in the area where the alarm was. He had removed the alarm from the car a while ago since he lost the key FOB. No matter. But when I get back down to my garage again, I will start snapping photos. I saw some differences between the 318i and the M3. Granted the 318i is a 96 and the M3 is a 95... I didn't think the headlights would be different from each other, at least from a glance.

I will snap photos when I get a chance. I hope I stumbled onto something informative. But if you guys have any ideas on what possible things may have been done, especially since the previous owner of the previous owner installed some HIDs and LEDs, that there may be something I am overlooking? Or maybe to look out for?

well the wiring for the most part should be the same regardless of the package i e m or none m. and most BMW approved HID kits plug right into the factory plug. unless some moron cut and hacked the wiring to install universal junk. but it would be nice to see pictures of the two.