reyxlp

I'll try and make a very long story as short as possible. I'm three mechanics in and still haven't solved it yet.

I've searched extensively and come across many similar issues but not the same combo of issues I'm having.

2006 CTS w/110,000 miles, no major issues before this.

I'll start with this: is there any related wiring, control modules, fuses, etc/whatever, between the headlamps and the rear upper center brake light? Also possible the driver side horn, which also isn't working? All these things seemed to start failing around the same time.I'm getting the dipped beam warning on the driver headlamp and the brake light warning for the center upper rear brake light. They always seem to happen around the same time.

Mechanics have ruled out bulbs and plug/outlet contacts, those seem to be fine. New battery and alternator is good- both tested and no issues.

I replaced both headlamp mount trays with new ones myself, that stopped the headlamps from coming loose over bumps or potholes. That used to happen and I thought that was the only reason I would get dipped beam errors. I would go over a bump, I'd get the dipped beam warning, one or both headlamps would stop working and sometimes I could get them working again just by turning the headlight switch off and back on, but usually I would have to stop, get out of the car and physically push them back into place, and then they'd work again.

Now, only the driver side headlamp will stop working but no correlation to rough road or bumps, and pushing it back in doesn't fix the problem, only turning the lights off and back on again will do it.

Anyone have any experience with this combination of issues?

Really appreciate any help..

Thanks!

Petza914

If the driver's side horn is the kid tone one, that fails frequently and is likely unrelated to your other problems. Has there ever been any water under the carpet and floor pad on the driver's side wire bundle and how us the wiring going to the headlights - flexible or crispy with insulation breaking off when you try to bend it.

How are the headlights coming out to where you have to push them back in - did you use the tool in the tool kit to lock them into place until they click - the arm underneath in the carrier needs to snap into the spit on the headlight housing.

Jonathan H

There is a good chance the dipped beam issue is related to failing insulation of headlight harness or perhaps the headlight internal wiring. For example, if you were to open the headlight and rub the wires with your fingers the insulation would crumble and make a huge mess - the exposed wires could then randomly or permanently touch each other causing issues.

There is a $50 harness right behind each headlamp (part number 955 631 239 11) that I bought on ebay.

When I messed up the wiring inside my headlight I snipped each wire and redid its insulation with heatshrink before soldering and applying more heatshrink to the soldered connection.

I would start by buying one harness and replacing on your driver side and seeing if your dipped beam error disappears. It's a little annoying to get the connector out but it's no more than a 25 minute job. I recall sliding the connector halfway out and running out of room so I then turned the connector 90 degrees to be able to remove and I was a little worried about something snapping off but nothing did. I also recall there being a little plastic square window pin that locks the connector -- it was easy to remove with a small flathead but very tough to reinsert with the new harness in due to the tight working space. I may have even dropped it in there and given up on it; no problems since.

If replacing the harness does not work it may be worth going into the headlight housing to peek around for flaking insulation but avoid this if you can because the insulation is so delicate that you could easily cause insulation to fall off when it would have been fine left alone (hence my experience).

aftCG

I just replaced my headlight harness this weekend. To the OP, replacing the trays won't help because there are no wiring contacts (now if your headlight is falling out because the plastic gears are jacked up then you needed them). The short wiring harness referred to (I paid not quite $60 from Pelican, shipped), clips into the back of that tray.

"connections look fine". So did mine. I eventually had no high beam, no low beam, no turn signal. I also found that shoving the headlight in firmly like people tell you to do won't work much of the time. I pulled the air filter housings out (one bolt) and could reach the back of the headlight as it goes in, and could push on the back of the harness plug to seat it properly. It was not a difficult job and now that I've done it, I would likely try that before buying a new harness.

I'm still chasing down why my "cornering lights" don't work but that's not the harness.

Zakowsky

To the OP - sounds like what I am dealing with wrt to dipped beam; could be just your ballast on the drivers side, mine did that for a while before stopping all together. It's easy to swap the ballasts and see if the problem moves with it.

reyxlp

Thanks so much for the reply!

I tried another mechanic. When I described the issues he immediately suggested it could be water corroding the wiring harness underneath the driver's carpet. He did find some corrosion and addressed that. Got the dipped beam on the drive home lol... So I'm glad the corrosion of that part of the wiring (which he said is super common on these cars at this age/mileage) is now repaired, but it didn't solve the issues, unfortunately.

The headlights used to come loose over harsh bumps or a pothole, etc. The driver's side would come out just a tiny bit, enough to turn off, and when I pushed it back in, it would turn back on again. The passenger side was worse. One time, after a rough bump in the road, the light cut out and when I pulled over to take a look, the headlamp had come out over an inch. I'm pretty sure it was a problem with the mounting trays because after I replaced them both, the passenger headlamp doesn't cut out anymore. The driver's side one still cuts out sometimes, but when it's out, the headlamp is still seated firmly in place and trying to push it back in doesn't make it turn on again.

I always use the special tool to "unlock" and "lock" the headlamps out of and back into place, however, even with the new trays, I don't ever feel like turning the arm ever "clicks" the headlamps into place. Even looking at both headlamps, the tab underneath which interacts with that arm doesn't look like it's designed to "click" or "lock" into place. One side is concave like the inner side of a hook clearly matching the shape of the arm so the arm can push it out when you're "unlocking" it, but the other side is fairly smooth/straight with no "catch" of any kind for the arm to lock into place. And the tab doesn't look worn or broken etc, not on either headlamp. So maybe there's something I'm not understanding about how they are supposed to "lock" with the arm but mine don't seem to be designed for the arm to lock the headlamp into place, but just to push it out when you need to remove it. Either way, the headlamps are super firmly in place now and no longer come loose.

reyxlp

Thanks for the info!

Replacing the trays did solve the problem with the passenger side headlamp and part of the problem on the driver's side. Both low beams would cut out and both headlamps would dislodge and start coming out of place if I hit a hard enough bump or pothole, etc. When I pushed them back in, the low beams would come back on after this happened. With the new trays, the passenger side lights never cut out anymore. The driver's side low beam still cuts out sometimes but not in relation to any bumps or rough road, and pushing the headlamp back in doesn't bring the light back on when it cuts out, so that was only part of the problem.

I will try to find that air filter housing bolt and see if I can remove that to replace the wiring harness. The first time I couldn't figure out how to do that and ended up taking off the whole front bumper to check everything but had to put it back on before I was able to get the new harnesses because I needed to use the car. Do you happen to have any pics or links to remove the bolt and take out the airboxes?

reyxlp

Thanks -- I will try that next! Though I can't help but to feel like all these problems are related to the same source issue.

Petza914

That's weird because the electrical plug to the light is not built into the tray, its a separate connector that actually locks together.

reyxlp

Yes but the headlamps are held in place by both the tray and also the connector so maybe both were failing. On the passenger side, it seems like it was definitely the tray. On the driver's side, the tray might have been part of the problem since the headlamp doesn't come loose anymore on that side either but it still cuts in an out so, issues remain... :/

reyxlp

Update...

Petza914: You were so right. I was able to "lock" the headlamps into place, I just had to apply a lot more force than I thought was needed. I was afraid it would break if I twisted harder but I did finally definitely hear and feel a very solid "click". I think the old trays were probably fine, I was just afraid I'd break something.

Jonathan H: I ended up replacing both wiring harnesses and thank you for the tip on turning the plug 90 degrees, I was also able to squeeze mine out by doing this. (I will add that I ended up securing the plastic tab behind the plug that holds it in place with my other hand to make sure I didn't break it off while turning and squeezing the plug out. I felt mine starting to bend a bit too far.)

Zakowsky: I swapped the ballasts, thanks for this.

I also ended up replacing both low beam bulbs for good measure, though the ones in there seemed fine.

Since doing all this, so far (fingers crossed, knock wood) no more dipped beam warning. Instead I now have "Brake Booster Faulty" hahaha... Win some, lose some.

Anyway- wanted to thank everyone who responded and correct some of the misunderstandings I'd posted on this issue.

Petza914

Great news and nice work !

Jonathan H

Glad the warning has disappeared!

Brake booster faulty is not too bad. Best to address before it wears out the booster motor. Feel each connection of the brake booster hose (maybe ~7 total hose-to-plastic-connector connections). I'm willing to bet the hose became brittle and split at one or more of those connections. Remove the two 10mm bolts of the metal booster-motor-mount and lift that mount assembly to have more room to feel around.

If you audibly hear a new non-normal motor from passenger side at startup and intermittently throughout your drive then that is the booster motor trying hard to make a vacuum and your leak may warrant a replacement of the entire hose assembly (~$130). If you don't hear the motor intermittently throughout your drive it's probably only one split connection and you can get away with pulling apart that connection, putting some electrical tape on the split end to re-form a circle, re-insert plastic connector into hose, and add more electrical tape to secure it in place.

Regardless of fix or replacement it will take 1 to 10 minutes of driving for the faulty error to disappear but it will go away on its own with no tool required if you successfully stop the air leak.