The purple wire has no voltage even when the key is turned to 'start'.
Absolutely nothing electrically speaking.
- Thread starter barichuk
- Start date
Frame is off the ground, axles not installed. I am at the end of video 21 or 22 and not finished all the details yet, wanted to get past the electricals first. I did jump it with a screwdriver and the starter spun, but I just can't get it to work with the key. I don't have the shift cable hooked up yet. If I go to the selector on top of the transmission, is park toward the front or back? I will get to the build thread soon and check it out. Thanks for the advice.
Anks329
Well-Known Member
You've got an automatic, right? Park is towards the back of the car. Two clicks forward should put you in neutral. Do you have wires plugged into the shifter? I don't think the car will start without that there.
Ark :D
Goblin Guru
Not sure about the shift cable, mine's a 5-speed.
I probably missed this, but, did you say whether or not the security light is on, on your cluster? If it's on, you'll need to do a key re-learn.
I'll save you a bit of reading because my build thread is ...... long, my problem ended up being that a connection on the fuse block end of my engine harness had a slightly-deformed pin. I had to fix that pin, then it started cranking. But, there's a ton of good advice from our compadres in there, you may find something that helps.
The bottom line is, when you turn the key, the ECM decides whether the conditions are right to crank the engine. If they're right, the ECM provides ground to a set of three pins in the engine harness, which in turn grounds the correct pin on a relay in the fuse box. With that relay pin grounded, power flows to the signal cable on your starter. *edit* I might have said that wrong now that I think about it.
I probably missed this, but, did you say whether or not the security light is on, on your cluster? If it's on, you'll need to do a key re-learn.
I'll save you a bit of reading because my build thread is ...... long, my problem ended up being that a connection on the fuse block end of my engine harness had a slightly-deformed pin. I had to fix that pin, then it started cranking. But, there's a ton of good advice from our compadres in there, you may find something that helps.
The bottom line is, when you turn the key, the ECM decides whether the conditions are right to crank the engine. If they're right, the ECM provides ground to a set of three pins in the engine harness, which in turn grounds the correct pin on a relay in the fuse box. With that relay pin grounded, power flows to the signal cable on your starter. *edit* I might have said that wrong now that I think about it.
Dale E
Well-Known Member
An automatic sends the signal to the starter purple wire from the transmission plug that plugs into the transmission black box . A maybe yellow wire ( probably the only other big wire in that harness. It should be the same size wire as the purple wire) will bring battery power to the shifter plug from the key. So if starter spun jumping with screw driver that is not your problem.. the problem is before the starter in the wiring from the key to the shifter plug and then to the starter.
I think hunting for wiring issues before everything is finished is not a good idea. You could easily be chasing suspected wiring problems only to find out it's because something was not finished.
If everything is installed and it still will not crank then we can start going systematically though symptoms until we find a problem.
If the car ran before it was taken apart there is no reason to first suspect there is something wrong with wiring.
Give me a call tomorrow if you need help with anything, I enjoy trouble shooting.
If everything is installed and it still will not crank then we can start going systematically though symptoms until we find a problem.
If the car ran before it was taken apart there is no reason to first suspect there is something wrong with wiring.
Give me a call tomorrow if you need help with anything, I enjoy trouble shooting.
CaptFrank2001
Goblin Guru
Be very careful. If you turn on the key & jump start the car "accidentally" in gear you can hurt or kill yourself.
Anks329
Well-Known Member
Just to clarify since I saw you mixing the acronyms around:
BCM: this sits in the footwell of the goblin and looks like this:
Fuse Block: This is on the back of the car above the engine:
ECM: Sits right in front of the fuse block and fits into the holder:
TCM: Sits right in front of the fuse block and fits into the holder:
I know I got tripped up with these names, hope this helps!
BCM: this sits in the footwell of the goblin and looks like this:
Fuse Block: This is on the back of the car above the engine:
ECM: Sits right in front of the fuse block and fits into the holder:
TCM: Sits right in front of the fuse block and fits into the holder:
I know I got tripped up with these names, hope this helps!
Ross
Goblin Guru
The GM PCM is the General Motors Power Control Module. It is the computer that runs my engine. Automatic cars have 2 computers, an Engine Control Module (ECM) and a Transmission Control Module (TCM). Not sure what your donor is. Anyhow, the PCM or ECM needs to talk to the other computers (The power steering computer and the Body Control Module (BCM) which is at the passengers feet). These computers talk to each other on the GM Local Area Network (GMLAN). If communication isn't working, the key start request doesn't get back to the PCM/ECM, and your starter motor doesn't get power on the purple wire.
These are the wires for the high speed GMLAN for my car. They are the same color on all the donors (Brown and Tan wires).
These are the wires for the high speed GMLAN for my car. They are the same color on all the donors (Brown and Tan wires).
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I am thinking the security light is the yellow one that looks like a padlock. It comes on when I turn on the key but goes out in 2-3 seconds.
Ark :D
Goblin Guru
That's correct, and that's good, because it means your key is being accepted by your TDM. That's bad, because it would have been an easy fix!
I'd follow Lonny's advice and not get too far ahead of yourself. These are complicated systems and it would be a waste of time to troubleshoot something that's not actually broken, just not far enough along in the process to work correctly yet.
One thing that may be worth considering; the donor was wrecked on the front left, which is the general area of the round connector from the transmission. The connector was damaged and the pins were bent a little. I straightened them and pushed the connector onto them. I am wondering if there should have been a plug attached there. The connection is not secure, nothing 'snapped' into place like with most connections.
Ark :D
Goblin Guru
I believe the lack of response from the butterfly means that communication is not happening from the BCM ("fuse box" in the passenger footwell) to the ECM. Check your data twisted pair; this is a pair of tan and tan/black wires that run from the OBDII port, through the power steering module, then to the BCM (the pair changes from tan to brown between the power steering module and the BCM), then back to the ECM.
Check continuity on both wires in the data twisted pair, from end to end (meaning, from the OBDII connector back to the pins in the ECM connector). I am not sure what pins they are in the ECM connector anymore; hopefully someone else can help you with that. If the power steering isn't plugged in or doesn't have power, or if the BCM doesn't have power, the communication won't happen. I saw earlier in the thread, you tested continuity through the 50-amp fuse, but I would test voltage to that pin on the BCM connector and make sure it's carrying 12v with the ignition turned on.
Check continuity on both wires in the data twisted pair, from end to end (meaning, from the OBDII connector back to the pins in the ECM connector). I am not sure what pins they are in the ECM connector anymore; hopefully someone else can help you with that. If the power steering isn't plugged in or doesn't have power, or if the BCM doesn't have power, the communication won't happen. I saw earlier in the thread, you tested continuity through the 50-amp fuse, but I would test voltage to that pin on the BCM connector and make sure it's carrying 12v with the ignition turned on.
Goblin Graber
Well-Known Member
Was the donor running when you took it apart? Since Lonny did the harness it’s not likely that the wiring is wrong.
It’s more likely that you have a connector that’s not plugged in all the way or one that got a bent over pin when you plugged it in.
It’s more likely that you have a connector that’s not plugged in all the way or one that got a bent over pin when you plugged it in.
Don't know if the donor was running. I can turn the engine by hand so I know it is not stuck. Been talking to Lonny. He is helping me troubleshoot, and I have found a couple of things. Progress is slow but it is happening.