Shut off while driving and will not start?

GMC HELP

MEMBER
2005 GMC SIERRA
6.0L
V8
4WD
AUTOMATIC
160 MILES

Stalled at 70MPH now it cranks and no spark. Replaced cam and crank sensors. Has plenty of fuel pressure and power to coil packs but no spark. Also a new throttle body.

Monday, November 21st, 2022 AT 6:09 PM

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

A very common issue with this engine is the ground for the ignition coils. They all share a common ground which is located on the driver's side (left) of the engine block.

Do me a favor. You will need to crawl under the driver's side so you can see the side of the engine block near the front. Look for a black wire going to a connector that is bolted to the engine block. If you see it, move it around and I bet the connector will fall apart.

On the other hand, if the connector is good, go to any of the injectors and disconnect one. Check the black wire for continuity to ground. If there is none, remove the black wire from the engine block and check for continuity between the injector black and the ground connector. If there is continuity, the wire is good, and we aren't getting a ground. Simply run a new ground to a known good location. You can even test it by running a jumper wire between the ground on the engine and the negative side of the battery.

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 questions.

Take care,

Joe

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Tuesday, November 22nd, 2022 AT 8:40 PM

GMC HELP

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Hey, thanks for your reply, Joe. I am going to recheck ground wire the connection to frame looks good not sure about where it mounts to block. I will test injector next if needed. I will follow up and let you know how it goes.

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Friday, November 25th, 2022 AT 2:00 AM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

The one for the coil will be on the passenger side of the truck toward the front of the engine. It is identified as ground 102 (G102) see pic 1. It is the same location on the engine block where the battery ground is located.

I was able to find a pic and highlight it for you. This is my first suspect.

Also, note there are three different splices that join the ground together. If you find everything is good at the engine block, go to one of the injectors and check the black wire for continuity to ground.

Let me know if you find it or if I can help in any way.

Take care,

Joe

See pics below.

Images (Click to make bigger)

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Friday, November 25th, 2022 AT 7:18 PM

GMC HELP

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Update: Truck is running now. It was the crank sensor not being seated flush to the block. It’s hard to believe and a bit embarrassing but figured I’d share to help someone else. It appeared to be flush but had a tiny bit more to go in. Working on it outside in the cold on a gravel driveway probably didn’t help. The moral here is pay attention to detail because you don’t want to wrestle with that starter more than once.

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Tuesday, December 6th, 2022 AT 4:42 PM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi,

Excellent. I'm glad to know you have it running. I didn't suspect that as an issue because it was replaced. However, it is really a simple error that anyone could miss.

Regardless, take good care of yourself, and feel free to come back anytime in the future.

Thanks for the update. I know it will help others in the future.

Joe