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2003 CTS
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Discussion Starter #1
I've read a lot of posts in the last couple days. It is apparent that the lighting circuits can be tricky.

My 2003 CTS does not have working front parking lights (little triangle ones). Side ones work.

Also the 2 front Amber DRLs do not come one (stalk OFF or AUTO and out of park).

The L/R signal function of the Amber lights does work.

I jumped the gun and replaced the flasher module under the dash. Now I have a spare. It didn't help.

I have yet to find a bad fuse. But please make suggestions where to look.

John
 

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06 CTS Sport/Luxury package
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I see you have everything listed... Except for the fact if you replaced the light bulbs yet or not. So where do you stand with that fact?

KOT
 

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Discussion Starter #3 (Edited)
I haven't yet. But in my defense the front left/right turn signals work. And from what I gather the bulbs are single filament and those are also used for DRL.

I have not checked the parking light bulbs. I was also hoping that it would be one thing common to both sets (DRL and Parking). Common ground wire? If maybe, then I need to know where it is.

And I've kinda been waiting for a bit better weather before I dig into that.

I just picked this car up a couple weeks ago. So I am learning it as I go. The systems on this vehicle are not what I've been used to. It seems to have a lot of the "it's known for that" type issues.
 

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Ok. The triangle bulbs are 194 and are most likely in need of replacement.

The amber lights not working as DRL but are for turn signal. Well the previous owner could've disabled them. Check out the FAQ on the first gen CTS forum. (Where you posted this thread.) There's a link in there to a site that shows you how to disable the DRL. Perhaps you can figure out if it was done and fix it, if you wish.

KOT
 

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Discussion Starter #5
I guess I'm getting in behind the bumper cover to check the triangles. I will check the flasher module wire harness. I know the pin on the module wasn't cut so maybe a wire.

I'll report back here once I get the opportunity to do these things.

Oh, I seen both removal of entire bumper cover, and just removal of front wheel well plastic as methods for getting at the bulbs. Is it necessary to remove the entire bumper cover or is it sufficient to just pull the wheel wells?

Thanks.
 

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Discussion Starter #7
Perhaps you can figure out if it was done and fix it, if you wish.

KOT
Yes. I definitely want to fix them. We're supposed to use them up here. That's why I will be surprised if they were purposely disabled. But stuff happens :)

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My DRL's only work when the car is in gear.
Yes. Indeed I had put on the parking brake, put it Drive and checked. No DRLs on.
 

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Discussion Starter #11
Status update: I got a chance to do some more checking.

Peeled back the driver side wheel well, and almost immediately seen a cut wire. Fog light (which I knew they were not working, but wasn't too concerned). Fixed the wire, now the driver side fog light works. Replaced the triangle parking light, it works. Replaced everything and proceeded to the passenger side.

Peeled back the passenger side wheel well. No sign of cut/broken wires. Pulled the fog light bulb, applied 12V, it works fine. So this portion of the fog light circuit is broken somewhere else. If anyone knows the circuit, let me know if the wire goes directly from drivers side to passenger side, of if it branches off somewhere else.

Replaced the passenger side triangle parking light, it now works also.

So the remainder of my lighting woes: DRL function (still need to check for possible cut wire) and one fog light.
 

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Discussion Starter #12 (Edited)
Solved the last bit for fog lights. Again peeled back the inner wheel well cover and started peeling tape off the plastic loom covering the wires, and the loom itself.

Sure enough, there is a broken wire and what appears to be a cut wire. Fixed them up, and BAM, both sides work now.

Got back under the dash for the DRL issue, followed the wires from the flasher module back as far as I could. But no cut wires.

So, up to now:
  • Engine running, in gear, looking for reflection, no DRLs
  • New module, no cut pin, no cut wires
  • No "optional" DRL relay in the under-hood fuse box, DRL fuse good
  • Wires presumed good to the lamps since they work as signals)
  • Lamps presumed good (see previous point)
  • Ambient light sensor good (AUTO works as expected)
My next test will be to check the DRL trigger wire into the flasher module so see if there is a signal when expected. Judging by the flasher module schematic, it's an active low (ground) input to turn them on. I'll ground out the wire myself and see. If that works, I assume that somewhere between pin H and BCM(?).

If there is no signal, does anyone know where this wire originates? BCM?
 

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Discussion Starter #13
Update: I dropped the plastic panels under the dash on both sides. Pulled down the flasher unit. Pulled down the DIM/BCM. I started the car. I grounded the DRL LOW signal wire from DIM to Flasher. I could hear a relay in the flasher module make a click sound. That seems to tell me that that wire is fine.

With some help, I put it in drive, grounded the wire, still no DRLs coming on. Even if the DIM/BCM was faulty, me supplying the ground signal and the relay clicking should mean the DRLs would come on.

I'm now lost as to what to do next.

Without a more complete wiring diagram (if there is such) I do not know where to check next. Other than verify the continuity of that DRL LOW signal wire, I cannot think of what other issues might exist as I have checked what I know of and all results seem to say that they should be coming on.
 

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When the headlights are on and the turn signal on, either left or right. What is going on with the front amber and side amber light? Do they flash ON and OFF at the same time. Or does one flash ON while the other is OFF?

KOT
 

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Discussion Starter #15
Thanks. Just went out to try that on my lunch break.

Car running, headlights ON, signal ON, side light and signal are alternating.

John
 

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Discussion Starter #17
Thanks for you help. Was worth a shot.

I will have time again this weekend to go over it again. Maybe I missed something.

Cheers
John
 
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