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Hi guys, me again.
As it seems I have lost my Highbeam functionality. When I turn them on the blue light in the instrument cluster comes on, so I guess it´s not the switch.
The relay clicks, also swapped it to the fuelpump relay, nothing. The 2 fuses have no power when the Highbeams are off and go to 12V when turned on, so at least the power reaches the fusebox.
Ah, and of course I checked both bulbs, they are OK, too.
It makes me wonder that both lights fail at the same time. Is there a plug or junction somewhere between fusebox and the lights which is interrupted ?
Any ideas ?
With a 12 volt test light connected to ground does the light illuminate when probing the 2 terminals closest to the fender ??...they are the load and control side feed...they are "hot at all times"...also if you jump terminals 30 and 87 (load side) the high beams should turn on...check that and that pic is below and don't shove anything in the terminals larger than a needle...you can use 2 of those if you have them to check…you might not have “control” of the relay which comes from the BCM (H1 in wiring) …the load side of the relay as you can see are 2 different grounds so wouldn’t be that.
Hi C5 Diag, thanks for your fast answer.
I checked as you said :
Light does come on on the 2 terminals closest to the fender (PIC A+B)
Jumped terminals 30 and 87 - nothing (PIC C)
What I found out in the process : Without the jumper cable between terminals 30 and 87, both fuses for the Highbeams have no power (PIC D)
With the jumper cable between terminals 30 and 87 in place, the have both 12 Volts (PIC E)
Any other ideas ?
Thank you in advance for your help. I watched all of your videos and enjoyed them very much :-)
Jump the relay again and see if you have power to fuses 23 and 24…if no 12 volts there you will need to look for an open circuit inside the fusebox…good idea to own a test light…seen many members make mistakes when using a DVOM doing this type of testing.
I checked that and with the jumper wire in place I have full 12,5 Volts to both fuses 23 and 24.
I also checked the ground connection directly at the plug that goes into the Highbeam bulbs. It is also correct. So I guess it must be the Plus connection from the fusebox to the bulbs ? Is it one cable which goes to the 2 bulbs or splits up on the way ? In the plan it says for both sides "LT Green/Black".
Looks like one feed wire is dark green/white (C4) and the other is light green/black (D4)…you will have to access the C1 connector and check the connector itself and the fusebox…I don’t know how they wired at the fusebox.
I will try and measure the continuity between fuseblock and bulb-sockets. Meanwhile I did some fiddling with the GMTech2 Software and found this here:
It´s a little strange that I have a short to ground and a short to battery. Does that shine some light onto what I should try next ?
Didn’t know you had a trouble code for this…here is how they want you to check the circuit with this code…I’ll look at this later…the manual says turn the high beams on at the stalk when jumping 87 and 30 so you can try that but that circuit feed is hot at all times so you shouldn’t need to turn on the high beams…I really don’t use these diagnostic trees because of this…it’s best to have a methodical approach to this instead of jumping around…start at the power source and work your way through the circuit…I would erase those 2 codes and see what comes back when the high beams are turned on…test for continuity between the fuses and the bulb…you will need to get down to see if you have 12 volts to the headlights with 87 and 30 jumpered…and you have 12 volts on BOTH sides of fuses 23 and 24 ??…did you ever check the bulbs themselves ??..HOW exactly did you check for ground at the bulb ??…there are 2 diff ent grounds but you still need to check that…you should not be using anything other than a test light or old headlight bulb for this…did you check for 12 volts at C4 and D4 on the Fusebox C1 connector with 87 and 30 jumpered ??
Good Morning,
I just found the trouble codes when I scanned the vehicle again. Before that only one trouble code from the ECM about the crank sensor. I will re-scan with the GMTech2, but today the car is at the workshop again, so this will have to wait.
I have 12 Volts on both sides of both fuses 23 and 24 when the relay is jumpered. Fuses are OK
I took out both bulbs and connected them to a 12 V source - both lit up, so they are OK.
I connected one side of my Voltmeter with a clamp to the Minus side of the battery and tested with the other side of the Voltmeter directly at the socket of the bulbs. It beeped, so I thought, ground is OK.
About this here " check for 12 volts at C4 and D4 on the BCM C1 connector with 87 and 30 jumpered" : The BCM is in the co-drivers footwell, right ? But isn´t the C1 connector in the fusebox ? I am confused about what to do here.
Good Morning,
I just found the trouble codes when I scanned the vehicle again. Before that only one trouble code from the ECM about the crank sensor. I will re-scan with the GMTech2, but today the car is at the workshop again, so this will have to wait.
I have 12 Volts on both sides of both fuses 23 and 24 when the relay is jumpered. Fuses are OK
I took out both bulbs and connected them to a 12 V source - both lit up, so they are OK.
I connected one side of my Voltmeter with a clamp to the Minus side of the battery and tested with the other side of the Voltmeter directly at the socket of the bulbs. It beeped, so I thought, ground is OK.
About this here " check for 12 volts at C4 and D4 on the BCM C1 connector with 87 and 30 jumpered" : The BCM is in the co-drivers footwell, right ? But isn´t the C1 connector in the fusebox ? I am confused about what to do here.
Thanks for your help, it is much appreciated.
Greetings from Germany
Oliver
Underhood fuse box C1 connector…I may have mis spoke..as illustrated above.
Good morning,
the trouble code didn´t come back after deleting it, but still no high beams.
I still have question about that last point "check for 12 volts at C4 and D4 on the BCM C1 connector with 87 and 30 jumpered"'
Do I understand you correctly : I unplug the C1 connector from the fusebox, then jumper 87 and 30 on the topside of the fusebox and then check for 12 V at C4 and D4 on the unterside of the fusebox ?
Thanks and greetings from excessively hot weather Germany
How about just a continuity check with your DVOM from the relay to one leg of each fuse ??…if you don’t have continuity you’ll just have to find where the wiring is bad…since it’s both sides look at the wiring and you can see where the splice is that goes to both sides so your issue is most likely from the relay leg to that splice.
I was sick of the lights going bad one after the other. As the car cannot be driven a few weeks, due to a short in the fuel pump wiring and the workshop being super busy, I re-wired the complete frontend of the car. All of it. Highbeams, lowbeams, parking lights, sidemarkers, flashers, foglights. Starting directly at the fusebox until the actual bulb. Took me a good 12 hours (not in one day) but now it´s just as GM intended it to be, only reliable.
On to the next surprise that will come with no doubt.
Have an nice day and greetings from rainy Germany.
2007 C6 High Beams no function
