07 LT 5.3L Sudden no start/crank

[J-Herkel]

Getting to the point..
2007 Tahoe LT 197k miles.
Suddenly would not start back up today after running fine for years and even started up 3 times prior today. Battery is brand new, took it out and tested it at the auto store. It's good. Alternator is fairly new. Starter was tested and is good. It will crank with a jumper wire in the relay. Obviously no signal from relay to starter solenoid. Not sure where the sending wire from the starter relay comes from. ECM? Ignition switch? Everything else in the vehicle runs perfect. Radio, lights, power windows, all strong. Just when I go to turn the key over to crank, nothing. And it was sudden. Any ideas?

 

[Doubeleive]

@rockola1971 do you know the 12v reference wiring on these from the ignition?

 

[J-Herkel]

@rockola1971 do you know the 12v reference wiring on these from the ignition?

I don't unfortunately. I've been trying to find a wiring diagram online but not having any luck.

 

[mikez71]

Try another relay yet?

 

[J-Herkel]

Try another relay yet?

I did. No luck. The problem is somewhere before the relay.

 

[mikez71]

It looks like ignition switch signals BCM through a PINK wire (J1-14)


BCM sends relay signal through YELLOW wire (J4-21)


Some scanners can tell if your key is in the start position.. Good luck and keep us posted!
I'm not sure if the "PASSTHRU" in the diagrams directly passes through, or if it's just there to show the relationship..

 

[J-Herkel]

It looks like ignition switch signals BCM through a PINK wire (J1-14)
View attachment 440752

BCM sends relay signal through YELLOW wire (J4-21)
View attachment 440753

Some scanners can tell if your key is in the start position.. Good luck and keep us posted!
I'm not sure the "passthrough" in the diagrams directly passes through or it's just there to show the relationship..

Thank you! ill see if i can trace some of those wires.