2006 Colorado DRL inop

2006 Colorado crew cab 4x4 3.5 5cylinder
This is my personal vehicle. I have had it a year and a half. DRLs have never worked since I have owned it. Outer bulbs were out (the ones used for DRL) I replaced all 4 bulbs. Turn signals all work now, parking lights all work. No more bulb codes. DRL indicator in cluster comes onwhen you put it in gear, etc, but BCM does not turn on DRL. AHL works. I can command the DRLs on with my Solus Edge. Anyone have any ideas?

What does the ambient light sensor PID read? Should be 1.75 to 4,9 KOEO.

With ignition off it should read 4,9.

I will look at it and post back.
I wiil probably not be able to look at it until the middle of next week. Thanks for your patience.
Ambient light sensor 2.1 volts uncovered, 4.5 volts covered.

As a temporary fix, i covered the light sensor with a face mask so the headlights are on all the time.

hoosierrick wrote: As a temporary fix, i covered the light sensor with a face mask so the headlights are on all the time.

are we talking about the DRL’s or the headlights? DRL’s usually turn on when the brake is applied and when the headlights are off. I think there may actually be no issue with the DRL’s. That said, there’s nothing wrong with having your headlights on all the time. I keep mine on especially in rural Texas

John Curtis wrote:

hoosierrick wrote: As a temporary fix, i covered the light sensor with a face mask so the headlights are on all the time.

are we talking about the DRL’s or the headlights? DRL’s usually turn on when the brake is applied and when the headlights are off. I think there may actually be no issue with the DRL’s. That said, there’s nothing wrong with having your headlights on all the time. I keep mine on especially in rural Texas

I am running the headlights because the DRLs don't work. The DRL indicator light comes on when it is not in park, parking brake off, auto headlights not disabled, not dark like it is supposed to, but does not turn the actual lights on.

I forgot to mention, all bulbs are stock incandescent. .No LED upgrades

I had the scanner on my truck this evening. It had history DTCs U1064 in the ABS module (lost communication with BCM/DIM) and history B2624 in the BCM (display dimming PWM circuit open). (I may have caused this code when I changed the original radio for a bluetooth unit to be handsfree compliant)
One thing I noticed in the BCM data; when the left turn signal is on, the DRL status remains off. When the right turn signal is on, the DRL status changes from off to on with the turn signal flash.

hoosierrick wrote: I had the scanner on my truck this evening. It had history DTCs U1064 in the ABS module (lost communication with BCM/DIM) and history B2624 in the BCM (display dimming PWM circuit open). (I may have caused this code when I changed the original radio for a bluetooth unit to be handsfree compliant)
One thing I noticed in the BCM data; when the left turn signal is on, the DRL status remains off. When the right turn signal is on, the DRL status changes from off to on with the turn signal flash.

Could it be it as simple as a bad local ground ?

This is a 06 I see. I have a 04 Tahoe and when I swapped the factory radio for a better aftermarket I had to get a security bypass module even wi5h a plain key. Ever since I replaced the radio though I get bcm codes along with interior lights being dimmer when clicked such as the two center map lights.

I open the passenger side visor, open the mirror cover to turn the light on and it allows the circuit to complete and the map lights come on from dim to regular as they should until the vehicle is turned off again. I also get the U codes described.

Might want to check and see if any of these conditions may be security/bcm related. I did later add white LED interior lights in the Tahoe and still have to activate thos lights with the vanity mirror located in the visor. While I have to activate them the switch to LEDs was well worth it as it’s brighter in the vehicle and others have asked why it’s so bright in there and like it.

My DRL and auto on/off headlights work properly as well.

Andy.MacFadyen wrote:

hoosierrick wrote: I had the scanner on my truck this evening. It had history DTCs U1064 in the ABS module (lost communication with BCM/DIM) and history B2624 in the BCM (display dimming PWM circuit open). (I may have caused this code when I changed the original radio for a bluetooth unit to be handsfree compliant)
One thing I noticed in the BCM data; when the left turn signal is on, the DRL status remains off. When the right turn signal is on, the DRL status changes from off to on with the turn signal flash.

Could it be it as simple as a bad local ground ?

I checked both of the bussed grounds. All looked good. cleaned off and applied dielectric grease. DRL still inop.

Dtnel wrote: This is a 06 I see. I have a 04 Tahoe and when I swapped the factory radio for a better aftermarket I had to get a security bypass module even wi5h a plain key. Ever since I replaced the radio though I get bcm codes along with interior lights being dimmer when clicked such as the two center map lights.

I open the passenger side visor, open the mirror cover to turn the light on and it allows the circuit to complete and the map lights come on from dim to regular as they should until the vehicle is turned off again. I also get the U codes described.

Might want to check and see if any of these conditions may be security/bcm related. I did later add white LED interior lights in the Tahoe and still have to activate thos lights with the vanity mirror located in the visor. While I have to activate them the switch to LEDs was well worth it as it’s brighter in the vehicle and others have asked why it’s so bright in there and like it.

My DRL and auto on/off headlights work properly as well.

I replaced my radio recently.I used the Metra LC-GMRC-01 Class 2 data buss interface. everything works.

I was playing with the truck tonight. While I had the DRLs commanded on, I pulled the DRL fuse. To my surprise, the DRLs stayed on. I also pulled the DRL relay, and the DRLs stayed on (commanded on by scan tool). Next I grounded the relay.(DRL not commanded on with scanner) The low beam headlights came on. I know early 2006 had parking light DRLs, and sometime during the model year they used low beams for DRL. This truck has a build date of 3/06. I'm confused at this point.

The pinouts on the BCM and the electrical center don't show any means to activate the DRL relay.
If all else fails, I am thinking about just running a wire to activate the relay with a switch. This would give me headlight DRLs. Not really first choice, but better than not having working DRLs.

Update: Still not fixed, but I have learned some things. This truck, by VIN breakpoint should have headlight DRLs. Also, my Snap-on scanner DRL output test is useless on this truck, as it turns on the parking lights, instead of turning on the DRL relay. I have a 2007 wiring diagram that shows the DRL wire as a ppl wire @ pin a36 at the bcm. I need to pull down bcm to see if the late production 2006 is in the same location.

FIXED!
I got a hold of a 2007 wiring diagram. It showed a purple wire (ckt 455) a36 at bcm, b5 at electrical center. I found a connector (c104) under the air breather with a crusty purple wire. I grounded the wire going back to the electrical center, and DRLs came on. Wired around the connector as a temp repair until I find a terminal with a stub wire that fits that connector.