Need some wiring diagrams please

[Dc8fixer]

Just picked up a 2014 Tahoe PPV. It will not crank. If I jumper the starter relay pin 30 to 87 it starts right up. I’ve got some hacked wires and think I might be on the right trail.But, I have no wire diagrams. Orange and black wire at the J1 connection to the ecu is cut and taped to a non factory wire. It runs up and thru the firewall and is just hanging by what I assume is the bcm under the dash. where some more wires are taped and messed with that appear purple. Any help or wire diagrams are appreciated.

 

[mikez71]

https://www.gmupfitter.com/wp-content/uploads/2021/05/2008_LD_ElectricalPickupsChassisCabs.pdf

For a 2008. Later years on gmupfitters seem to just show mainly plug pinouts, very few diagrams, like below for a 2014.

https://www.gmupfitter.com/wp-content/uploads/2021/05/2014_Elec_HD_FS_CKTruck_100713.pdf

Might be you need both to cover any changes made..

 

[Dc8fixer]

Thanks Mike! Looks like my purple wires at the bcm have to do with the power windows. This was a K9 PPV. So there was probably crap to open the windows for the dog I’m guessing. Today I found some crap and wiring under the dash. Safety stop an anti theft system for law enforcement. I’m guessing this might be part or all of the problem. Looks like it’s spliced into all kinds of crap.

 

[iamdub]

Just a flying leap guess: I recall PPVs having a feature where they could press a button before turning the key off. This allowed them to remove the key to lock the car while leaving the engine running. I don't know how this device worked. But, if it was tapped into factory ignition wires then removed, maybe there are some circuits left open.

 

[Doubeleive]

have you checked for a hidden floor button that has to be pushed first? it would be under the carpet in the drivers footwell area

 

[Dc8fixer]

Haven’t checked for any hidden floor button. Just discovered the switch at my knee. Then uncovered the safe stop wiring mess. But from what little I read about that. Sounds like it’s more a system to keep the car from moving not cranking. I really think my problem is the J1 orange/black wire at the ecm. It’s just taped to a black wire that is going up and thru the firewall not hooked to anything.

 

[mikez71]

This maybe the better wiring diagram to start with, 07 utilities. The 08 maybe for pickups only..

https://www.gmupfitter.com/wp-content/uploads/2021/05/2007_LD_ElectricalUtilitiesSUV.pdf

 

[swathdiver]

Well, if those wiring diagrams don't work, get a subscription to the shop manual at AllDataDIY which includes the wiring diagrams for everything. The new AllData even has color interactive wiring diagrams to help trace wires across multiple pages.

How many DC8s are still flying?

 

[Dc8fixer]

Lol, not as many dc8’s flying as there are Chevy Tahoes on the road…How much is a alldata subscription? I looked at it awhile back. I would only need it for the Tahoe. I just wired a start switch to my pin 30 and 87 on the start relay for now.

 

[swathdiver]

Lol, not as many dc8’s flying as there are Chevy Tahoes on the road…How much is a alldata subscription? I looked at it awhile back. I would only need it for the Tahoe. I just wired a start switch to my pin 30 and 87 on the start relay for now.

$20 for a month and triple that or so for a year, I forget exactly. Since it is more vehicle specific now, we bought subscriptions for the Yukon and newest Sierra.