2014 Silverado 1500 LTZ, 5.3l 4x4.
A few months ago, my truck would not start...this with a brand new battery and all new cables. I had the infamous grounding problems and just replaced all the cables. So it won't start, but the interior lights come on, etc. The only way I can get it to start again is to remove the positive cable from the battery to that junction board right beside the battery, reattach the cable and then it will start...and everything inside resets. It will go a couple weeks and do the same thing. I never know when. The battery store guy says it is most likely that junction block next to the battery which has other cables attached and a few fuses. He says something is "tripping" the system and when I disconnect and reconnect, it resets. I don't think it is this junction block...it doesn't do anything but provide a junction, and none of the fuses blow. Has anyone else had this issue, and if so, what might be the cause? Bad ECM??? I hate to go to the dealer where some nimrod will screw around with it for hours and charge me $1k or more.

 

So to clarify ... the starter cranks, but the engine won't run?
Any warning lights on the dash? antitheft light?

 

No, I did not say the starter cranks. It does not start, no warning lights...of any kind.

 

ok well that's usually what is meant by "no start". Updating your title to reflect this ....

Try swapping your starter relay.

 

Installed new relay...that didn't work. Only thing that works is disconnect the battery and wait 2-3 minutes...and then it will start. It did this no start twice today, and usually it will go 2-3 weeks before acting up again. Second time, I timed it at a bit over 2 minutes with battery disconnected, and it started. I think it may be the ECM...something that resets with the battery disconnected.

 

well you don't know, and the ECM is a very expensive guess. There's still plenty of diagnosing you can do to pinpoint the problem.

Try bypassing the relay.

 

Well yes, I don't know if that is it. That is why I am on the forum to get advice. I don't know how to bypass the relay...since I have never had this issue, so I guess I will look somewhere for how to do that...

 

this is a standard automotive relay


to bypass it (simulate the switch closing), just shove a piece of wire into the holes where pins 30 and 87 go, momentarily. be ready to pull it out again.

 

Okay, thanks. I'll try that right now. Will this tell me anything if the system is working now? Or do I need to wait until I cannot start it?

 

Ran the jumper from 87 to 30, and the engine turned over great, but did not start...