2015 Silverado Won't Start!

enroberts · December 16, 2018

2 hours ago, tbarn said:

I will guarantee you there a many more codes in the system. Need a proper scan to start with.

Proper scan? You mean like BCM and ECM scan? My ECM isn't doing much of anything because nothing can connect to it.

SS502 · December 16, 2018

5 minutes ago, enroberts said:

No, factory gauges.

The two on the left are factory? Not familiar with them...

enroberts · December 16, 2018

Just now, SS502 said:

The two on the left are factory? Not familiar with them...

Oh, sorry, those are definitely not factory lol. I actually removed them today.

enroberts · December 16, 2018

I just ordered a new starter, positive battery cable, and negative battery cable. Amazon will have it to me by Wednesday. I'll throw it all on and see what happens. If still no start, I'll put it on my trailer and tow it to the dealer for a scan and see if they have an issue connecting to the ECM too. As of now, I'm leaning towards a failed ECM.

tbarn · December 16, 2018

Proper scan with proper equipment like GM's GDS2 and an MDI . Or other high end scanner.

tbarn · December 16, 2018

You have to know which modules are communicating and which are not. Then check power and ground at them. Then if they have power and ground you next check the networks. It's a process and can be fairly quick or take a long time. Clearly, if the PCM does not have power or ground, you don't need to check the onstar module. One tip, check between the battery and right front fender for rodent damage. It's a common place for them to chew wiring. One more thing, any module on the high speed circuit can take the whole circuit down. The Onstar module is a common module to do just that. You can't just unplug a module to test. You have to jump the network circuits.

Edited December 16, 2018 by tbarn

enroberts · December 16, 2018

13 minutes ago, tbarn said:

Proper scan with proper equipment like GM's GDS2 and an MDI . Or other high end scanner.

Makes sense. If the cables/starter don't resolve it, that will be my next step at the dealer.

enroberts · December 16, 2018

3 minutes ago, tbarn said:

You have to know which modules are communicating and which are not. Then check power and ground at them. Then if they have power and ground you next check the networks. It's a process and can be fairly quick or take a long time. Clearly, if the PCM does not have power or ground, you don't need to check the onstar module. One tip, check between the battery and right front fender for rodent damage. It's a common place for them to chew wiring. One more thing, any module on the high speed circuit can take the whole circuit down. The Onstar module is a common module to do just that. You can't just unplug a module to test. You have to jump the network circuits.

Sounds like an expensive trip to the dealer for them to waste a bunch of time combing through module after module.

tbarn · December 16, 2018

Not really wasting time. You have to get to the bottom of the issue. Is the doctor wasting time diagnosing? This thing ain't no 78 Cheyene. They are complicated.

Supreme Pizza · December 16, 2018

59 minutes ago, enroberts said:

I just ordered a new starter,

It is possible for the starter to cause electrical problems, but I think it would probably have to short out internally, combined with a simultaneous solenoid failure resulting in a "stuck on" position. This would kill you battery pretty quickly. If you want eliminate the starter as a possible cause, you could disconnect the wires from the starter, and turn the ignition on. If everything works perfectly on the dash, reconnect the starter and check the dash again. You can also bench test the starter by using a car battery and jumper cables. Or you can test the stater in the vehicle by crossing the terminals with a screw driver.

Edited December 16, 2018 by starman8tdc

enroberts · December 29, 2018

For those interested, my ECM failed. Replaced it at the dealer today and had it reprogrammed. Back in business!

On 12/15/2018 at 10:51 PM, tbarn said:

You have to know which modules are communicating and which are not. Then check power and ground at them. Then if they have power and ground you next check the networks. It's a process and can be fairly quick or take a long time. Clearly, if the PCM does not have power or ground, you don't need to check the onstar module. One tip, check between the battery and right front fender for rodent damage. It's a common place for them to chew wiring. One more thing, any module on the high speed circuit can take the whole circuit down. The Onstar module is a common module to do just that. You can't just unplug a module to test. You have to jump the network circuits.

Sounds like an expensive trip to the dealer for them to waste a bunch of time combing through module after module.