When I first purchased my 09 with one Tb w/I6 the DRL's weren't working at all,a swap of the dash sensor solved that problem. The other day I noticed the DRL's are operating at "FULL" power same as if the low beams were on. Anybody have this problem?...Please be advised I already swapped out the solid state relay in the fuse box with one from a friend's Tb who's DRL's are working properly and there was no change in mine. Any thoughts on what I can check next?...TIA
Daytime running lights
- Thread starter retiredcopper
- Start date
You might find THIS Thread... Interesting...
gmtnation.com
SOLVED! - No DRL?
I am puzzled. My 2003 Envoy XL has no daytime running lights. My headlamp switch does not have a setting on the switch to deactivate them (only has three settings, -off, parking, and on - which is not what it shows in my manual). I can't remember ever noticing if they were ever on. Does that...
gmtnation.com
MR,I had already gone thru these,were no help finding out why the DRL's are working at full power instead of the 50 or 60%...much appreciated for the post....I'll keep digging....stay safe!You might find THIS Thread... Interesting...
SOLVED! - No DRL?
I am puzzled. My 2003 Envoy XL has no daytime running lights. My headlamp switch does not have a setting on the switch to deactivate them (only has three settings, -off, parking, and on - which is not what it shows in my manual). I can't remember ever noticing if they were ever on. Does that...
A curiosity,,, how are you measuring the duty cycle of the DRLs?? Oscilloscope? Frequency meter? And are you measuring the output of the HDM or the control signal? Maybe checking a PID of the BCM??
Blckshdw
Moderator
It almost sounds like the 2nd daylight sensor failed the opposite way, making the vehicle think it's always nighttime. 
There IS a peculiarity with the Left Headlight, the Left Turn Signal and Fuel Pump Relay sharing a Common (Sketchy) Ground that can have an effect upon each other as per this image:
Also... The BCM (encompassed in the Dotted Line Rectangle on the Upper Left Side of this attached Diagram) seems intimately involved with the Headlamp Relay... so perhaps looking over the Fuses and Connection therein may reveal more possibilities... this Schematic commends itself to a bit of close study...
Also... The BCM (encompassed in the Dotted Line Rectangle on the Upper Left Side of this attached Diagram) seems intimately involved with the Headlamp Relay... so perhaps looking over the Fuses and Connection therein may reveal more possibilities... this Schematic commends itself to a bit of close study...
Blck,first I'm hearing of a 2nd sensor...might you know where it's located?It almost sounds like the 2nd daylight sensor failed the opposite way, making the vehicle think it's always nighttime.
Blckshdw
Moderator
Sorry, I meant the sensor you used for the initial replacement seems like it failed.
Can you confirm if the parking lights are also on during the day? Or any of the interior lighting of the switches and dash are on?
