2018 telematic module issue.

[SteveSRT8]

Our youngest service van experienced dramatic electrical issues last week. 2018 Chevy Express 3500, 6.0 gas engine. Hesitation, limp mode, all gauges going crazy, every light and warning going off, etc. Crawled all over it for 2 days looking for the problem.

It was Onstar! This module controls EVERYTHING, and it can put you on the side of the road! Had to go to the stealership, they can replace it for 1200 bucks (with zero available parts) or bypass it for 400 bucks.

We cannot wait as biz is crazy this time of year. We will be bypassing...

 

[TCL]

Our youngest service van experienced dramatic electrical issues last week. 2018 Chevy Express 3500, 6.0 gas engine. Hesitation, limp mode, all gauges going crazy, every light and warning going off, etc. Crawled all over it for 2 days looking for the problem.

It was Onstar! This module controls EVERYTHING, and it can put you on the side of the road! Had to go to the stealership, they can replace it for 1200 bucks (with zero available parts) or bypass it for 400 bucks.

We cannot wait as biz is crazy this time of year. We will be bypassing...

Trying pulling the ONSTAR fuse and then disconnect battery. Reconnect battery and see if that helps.

 

[SteveSRT8]

All the modules were disconnected, battery was replaced, etc. We originally thought it was the battery cables or connections due to our experience with these vehicles. The factory battery was leaking as there was a tiny bit of corrosion on the negative connection and everyone knows how crazy the GM's can act with that issue! We pulled the three (aftermarket included) fuse boxes and traced everything we could find.

Onstar has never been on our trucks before this van. I didn't want it in the first place!

 

[boom10ful]

Probably acts like a gateway module for the other modules. Brings CANBUS down and causes all sorts of issues.