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V1 No Crank when Headlights off
RobC76
Well-Known Member
- RobC76 Well-Known Member
Well I have been digging for what I have screwed up in my wiring harness lol. It’s seems as though the only way I can the BCM to power up completley, the dash cluster message center to power on, the obd2 to communicate, the car to crank, the throttle to cycle is to turn on the marker or headlights lol. It’s like the headlight switch is powering the run side of ignition switch. Thinking about pulling harness out of car and pinning out every pin. Any ideas before I do something else as dumb as I must have already done lol.
Thanks
Thanks
Ross
Goblin Professor
- Ross Goblin Professor
I would chase the current problem. Do you have the wiring diagram for your donor car? Your signature doesn't mention what your donor is.
For my 2006 LSJ, There are 2 fuses before the ignition,, and it also needs 5V power.
Then the key can energize the run/crank relay, which will power up 5 more fuses.
For my 2006 LSJ, There are 2 fuses before the ignition,, and it also needs 5V power.
Then the key can energize the run/crank relay, which will power up 5 more fuses.
RobC76
Well-Known Member
- RobC76 Well-Known Member
Thank you
I will work on getting diagrams. It’s a 2008 SS/TC.
I purchased ALLDATA which for some reason has no mention of body controller. Electrical diagnosis is not yet in my wheelhouse lol. I thinks it’s about to be.
I didn’t have a donor when I started my build log for my original chassis. This chassis is 247 which I purchased from the guy that was going to make the harness for Goblins. Once I get everything working / driving I plan to start the other one with a different engine configuration.
Appreciate your help!
I will work on getting diagrams. It’s a 2008 SS/TC.
I purchased ALLDATA which for some reason has no mention of body controller. Electrical diagnosis is not yet in my wheelhouse lol. I thinks it’s about to be.
I didn’t have a donor when I started my build log for my original chassis. This chassis is 247 which I purchased from the guy that was going to make the harness for Goblins. Once I get everything working / driving I plan to start the other one with a different engine configuration.
Appreciate your help!
- Gtstorey Goblin Guru
If I remember the previous discussions of starting only with head lights on, I would probably continue the diagnostic of the IGN fuse I previously mentioned. Is that fuse getting power to it when trying to start. Even if the fuse is good, it sounds like there still might be trouble on it. There can't be to many circuits that either back fed or grounded by the headlights that make the car start only with the headlights on.
But this is just a guess since we can't know what mistakes you might have made when wiring. If you connected the headlight to a wire instead of the correct one, that will be hard to figure out without being hands on.
But this is just a guess since we can't know what mistakes you might have made when wiring. If you connected the headlight to a wire instead of the correct one, that will be hard to figure out without being hands on.
RobC76
Well-Known Member
- RobC76 Well-Known Member
No I did try that however. Marker / headlights have to be on.
So I think everything is behaving normally except for:
The headlight switch is acting like the ignition switch lol. So in order to:
Fire up BCM completley,
Fill in info in the dash message display,
Operate throttle plate,
Start engine, and a few other nice features lol you have to turn on marker lights
Desert Sasqwatch
Bigfoot Goblin
- Desert Sasqwatch Bigfoot Goblin
Are your headlights grounded? I seem to recall there is a ground lead for the headlight harness that gets connected on the battery box tray. Weird problems like this can occur when a voltage potential is looking for a ground, it can take some strange paths to get there which it can appear to be stray power in other circuits.
Desert Sasqwatch
Bigfoot Goblin
- Desert Sasqwatch Bigfoot Goblin
But we agree this is a grounding issue, as the voltage is trying to compensate for an important ground not making contact somewhere in the circuit. 
And from the title and symptoms expressed, there is something particular about the headlight circuit/harness wiring that plays into this issue.
And from the title and symptoms expressed, there is something particular about the headlight circuit/harness wiring that plays into this issue.
RobC76
Well-Known Member
- RobC76 Well-Known Member
I got all the schematics from a source at GM and I'm starting with grounds and power at BCM then moving onto the start circuit. Oddly enough I hooked up headlights and taillights today and the running lights have a very low glow even with everything off and headlight stalk switch unplugged.
I'll keep you guys updated as I move forward.
Thanks for your help and responses
I'll keep you guys updated as I move forward.
Thanks for your help and responses
- Gtstorey Goblin Guru
may not be a ground issue since there have been problems with the same symptoms with the fuse shot. But the dim lights when nothing is supposed to be on pushes it that direction.But we agree this is a grounding issue, as the voltage is trying to compensate for an important ground not making contact somewhere in the circuit.
