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  Topic Review (Newest First)
06-24-2019 08:40 PM
JohnWR The diagram looks essentially identical to the headlight/DRL diagram for a 2008 Sky, so you are good there.
While the BCM switches negatives to turn on the relays, the relays are switching positive to light the lamps.
This means that if your low beams are working, the grounds are OK because they are the same for both.

There is a jumper running from X3/D5 to X3/B5 to connect power from the DRL relay to the left low beam.
Power for the right DRL back feeds through the left low beam fuse to get to the right low beam fuse and then to the right DRL.
The D5-B5 jumper shows as a wire, not a resistor, and I did not read any significant resistance across it.
Regardless, with the DRL relay on I read 12.1 V at the DRL fuse and 10.8 V at the headlamp fuses, so something is happening.
06-24-2019 05:54 PM
JohnWR Don't your low beams work properly?
06-24-2019 05:48 PM
psmith32 Thanks for the diagram. The mods was posted by a Gm engineer 10 years ago I would think someone else would have this same problem. It was done correctly but I'm going to reverse tomorrow anyway and see. Turn signals dont seem to have any connection to drl's but one never knows.
06-24-2019 05:27 PM
JohnWR TS, that diagram looks pretty much like my memory of the Sky circuit, but I will confirm tonight.

If the low beam headlights work it isn't a ground problem because they share a ground.

Also, unless the jumper from the DRL relay to the headlight circuit is actually an unidentified resistor, the DRLs run at full voltage.
Note that the relay simply provides battery voltage to the low beam lamps from a different direction, and that they are still wired in parallel.

DRLs used to be series wired, but it seems that GM got away from that at some point before us.
06-24-2019 05:21 PM
psmith32 Thanks i'll have to do some wire tracing
06-24-2019 05:21 PM
TomatoSoup
Quote:
Originally Posted by psmith32 View Post
Tomatosoup

Yes I changed relays no "click". So I grounded one side (pin 86 or 85) and both DTR's comes on. So now It's on to tracing the ground wire.
After doing this I was not thinking the BCM because it was supplying 12 Volts to relay. Could it instead be controlling the ground?
Yes, the BCM controls most things by switching the ground. I've attached the Solstice headlamp wiring diagram. Should be almost the same as the Sky, apart from the different number of bulbs.

Quote:
Originally Posted by psmith32 View Post
I did a few weeks back do the side turn signal mod (2). the're now flashing with the turn signal. I'm not sure if this circuit is connected with DTR's but it does require cutting a ground wire.

Ahhhhh, now the truth is coming out. That's what we, in the business, call "a clue"!

Yes, I think you need to revisit that mod and verify you did it correctly!
06-24-2019 05:18 PM
Amorget In general ECM/PCM/etc control grounds, not +12v.
06-24-2019 12:39 PM
psmith32 Tomatosoup

Yes I changed relays no "click". So I grounded one side (pin 86 or 85) and both DTR's comes on. So now It's on to tracing the ground wire.
After doing this I was not thinking the BCM because it was supplying 12 Volts to relay. Could it instead be controlling the ground?
I did a few weeks back do the side turn signal mod (2). the're now flashing with the turn signal. I'm not sure if this circuit is connected with DTR's but it does require cutting a ground wire.
I'll have to snoop around for a wiring diagram.

Johnwr

I took the bulbs out cleaned all the connections and so far there back to normal thanks for advise...on to the DTR's
06-24-2019 08:46 AM
TomatoSoup
Quote:
Originally Posted by psmith32 View Post
Now on to the next problem
DTR's now not working. low beam works, covering light sensor turns low beam on. relay 48 {dtr} has power (12 volts) on pin 30 and 85.
but relay never engages. it seams there is a resistor wire to drop voltage to 9 Volts. Anybody have an idea were it is located.
My thought is is blown.
There is no resistor. The 'dimming' of the DRL headlights is done by the DTR relay simply switching the two lights to series (so they divide the voltage and get ~6V each). If your relay isn't engaging, it may be faulty. To check, switch that relay with another similar one that's not being used for the moment and has the same shape and pins (such as the high beam relay, #72 ). If THAT still doesn't work, then you have an issue in the wiring to the relay (or in the BCM).
06-23-2019 10:55 PM
JohnWR What about the brake lights?
06-23-2019 08:37 PM
psmith32 Now on to the next problem
DTR's now not working. low beam works, covering light sensor turns low beam on. relay 48 {dtr} has power (12 volts) on pin 30 and 85.
but relay never engages. it seams there is a resistor wire to drop voltage to 9 Volts. Anybody have an idea were it is located.
My thought is is blown.
06-22-2019 04:29 PM
JohnWR If you replace it, yes, it will have to be re-calibrated. But you may just find that it is loose, and then it should be OK.
06-22-2019 03:33 PM
psmith32 Thanks john, I'll check tomorrow. I suspect that if I replace the pedal sensor/switch I will have to have it programed?
06-22-2019 02:41 PM
JohnWR That sounds normal for the running lights. In auto and daylight the DRLs will be on, but the running lights will not. Covering the sensor simulates night so the DRLs will switch to headlights and the running lights will turn on. Manual of course gives you manual control of headlights and running lights, and the DRLs will be off.

The brake lights and rear turn signals use the same filament and the same BCM output, so if the turn signals are working that part is OK. That leaves the brake pedal switch. You can check to see if it is broken or loose.
06-22-2019 01:40 PM
psmith32 yes. The running lights Key off/on only work when manually turned on OR the photo eye is covered up never in auto.
Turn signals work fine. Brake light is always on, turns off first time pedal is pressed stays off for 5 seconds then turns back on.
If I repeatedly press the brake, The lights work correctly until 5 seconds of no pedal movement then turn on.
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