P0351-0353-0355-0357 coil pack problem

[08z71bgm]

So before we go down this road. I’ve swapped the whole bracket packs and harness for another and code is still there.

My question is where are the grounds for this bank of coil packs off the main harness? Is it behind the cylinder head?

I have a feeling the ground broke off somewhere and is shutting down the whole bank of coil packs. Just don’t know where it is.

 

[Fless]

It might be more efficient to verify which circuit (ground or power, control) is missing. That will let you focus your diagnostics. When you test the input to the harness, what do you get?

 

[Doubeleive]

So before we go down this road. I’ve swapped the whole bracket packs and harness for another and code is still there.

My question is where are the grounds for this bank of coil packs off the main harness? Is it behind the cylinder head?

I have a feeling the ground broke off somewhere and is shutting down the whole bank of coil packs. Just don’t know where it is.

just ground that side to the frame
that will get you running in the meantime till you hunt down the break

 

[Doubeleive]

the upfitter guide may show it or maybe @swathdiver has the diagram handy

 

[08z71bgm]

Checked all the fuses. Voltage. What’s odd is nothing showing OL. So why is the whole bank dead?

Engine runs without a main harness attached to the coil pack harness the same as if it was plug in. Makes no difference.

 

[08z71bgm]

Upfitter doesn’t show the ground locations

 

[08z71bgm]

It was definitely ground. Jumped it out and grounded it.

And still no one knows where the factory ground stud is for it? Which was my original question still not answered!

 

[Fless]

I'm sure that AlldataDIY would have the wiring diagrams for your truck.

So you had ground at the harness connector when you tested before? Weird.

 

[08z71bgm]

Yup. I have tons of spares and I spliced one out and ground it to the firewall and boom idles smooth. Which was my whole huntch from the getgo.

 

[08z71bgm]

No one has digital service manual here? Hard to believe. You guys should upload and sticky these docs for people.

 

[swathdiver]

So before we go down this road. I’ve swapped the whole bracket packs and harness for another and code is still there.

My question is where are the grounds for this bank of coil packs off the main harness? Is it behind the cylinder head?

I have a feeling the ground broke off somewhere and is shutting down the whole bank of coil packs. Just don’t know where it is.

I'm afraid it's your ECM:

Both banks share the same ground location, G102, which is at the lower left front of the engine.

We have our own subscriptions to the shop manual.

 

[08z71bgm]

If it’s the ecm then grounding myself wouldn’t fix it. It did so the ground wire is broken somewhere. Most likely where that ground stud is. I’ll check tomorrow

 

[08z71bgm]

So looked at that subscription and I ain’t got money for that. Inflation and shit took it all away.

Thanks for telling me where it is

 

[swathdiver]

So looked at that subscription and I ain’t got money for that. Inflation and shit took it all away.

Thanks for telling me where it is

It's $20 for a month. SeriousCTBuyer sells a download or disc on ebay to the shop manual too, just not as nice and updated like AllDataDIY.

 

[08z71bgm]

That 20 bucks is gas or some food. Inflation blows when my paycheck never inflated as much.

I looked on eBay for some and it looks like all scams.

 

[08z71bgm]

Either way it’s fixed while I find the broken ground. Prolly broken at the block behind the PS pump.

 

[08z71bgm]

Two wires on the block in the front were definitely broken off and handle the grounds for the coils on both banks. The harness I have in the truck is for an 08-09 Tahoe/Yukon 4.8-5.3 flex or gas don’t matter.

Once I replaced the new ring terminal engine ran just fine.

FYI it’s not the ecm.

Broken ring terminal for both banks of coils.