Electrical and drivetrain problem

JM77

MEMBER
2007 CHEVROLET SILVERADO
211,000 MILES

I replaced my transmission and transfer and I went to test it and it started and ran but wouldn't move. After close inspection I realized there was a gap between motor and bell housing. So I dropped the transmission double checked converter and reinstalled. After reinstalled no more gap however now truck won't start. My starter had a short so I replaced it and replaced the neutral safety switch and still nothing. That's when I noticed a wire on back of motor looks either pulled out of something or cut and I'm assuming it happened the second time I installed transmission. It's a black wire with white stripe and I can't seem to find where it was.

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,858 POSTS

Hi,

Black with a white tracer is ground. I have a feeling you broke this wire off the rear of the engine block. It is (G103) and is located on the right rear of the engine. If you lost that ground, the PCM lost ground.

I went through the entire wiring schematic for a 5.3L 2wd vehicle. I don't know if that is what you have, but that ground is required on most.

I attached the entire powertrain management wiring schematics below. There are a total of 5 pages of schematics. I had to cut each page in half to make them readable for you. I did overlap them.

Also, I highlighted as many black/white wires I could find. The neutral safety switch also grounds through a wire that color. However, I have a feeling it is the main ground behind the engine.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.

If I have the wrong engine size, let me know.

Images (Click to make bigger)

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Tuesday, September 7th, 2021 AT 8:51 PM

JM77

MEMBER
3 POSTS

Hey, I actually did some research and came up with same idea. However I have no idea what this looks like or how to find it. Do I need to get a new one because of this so if you can draw a map or something also my truck is 4x4 with the 6.0 so is it still same answer?

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Wednesday, September 8th, 2021 AT 4:36 AM

JM77

MEMBER
3 POSTS
2007 CHEVROLET SILVERADO
6.0L
V8
4WD
AUTOMATIC
211,000 MILES

You answered my first question. That was what I was leaning towards also. However I don't know what it looks like that the black wire with white stripe goes. Your reply was for the 5.3 2wd. Mine is 6.0 4x4 so if you can send me a drawing or map of where that wire goes and when you say right side of block are you referring to passenger side or driver side? Thanks in advance.

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Wednesday, September 8th, 2021 AT 10:36 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,858 POSTS

Hi,

I attached the schematic below of your vehicle (6.0L). The black with a white tracer on this one is on the front of the right cylinder head. That would be the passenger side. They determine the side based on sitting in the vehicle.

I attached the schematics below for your vehicle. However, here is what I want you to try. Simply check that wire for continuity to ground. If there is none, then turn the key to the run position and just confirm there is no power to it.

If there isn't power, then simply ground it to the engine block. This schematic shows very little as far as a black/white wire.

Let me know what you find or if you have other questions. One last thought. If possible, take a pic of the wire and location and upload it for me to see. Make sure it does have a white tracer (they get dirty and hard to tell sometimes).

Also, I may have found another possible location. The transmission control module ground is via a black/white wire. The schematics indicate (no location provided). I suspect that is the wire and it is a ground. I circled it in the last pic.

Put a connector on the wire and bolt it to the engine or anywhere you get a good ground and try it. Every black/white wire is a ground, so that is what I would try. As long as it is grounded, the original location isn't important. It likely broke.

Take care and let me know what you find.

Joe

See pics below.

Images (Click to make bigger)