2008 silverado 2500 RPM gauge not working

[Chad Webster]

2008 2500hd RPM gauge is not working as well as trans temp reads between 99 and 112 degrees on the dash.  Tried to hook it up to read codes but will not connect to the Vin.  It just keeps setting off all the dash lights like abs light.  Being told possibly bad body ground and or bad pcm.  

[Jsdirt]

This is one of those problems that can literally have 100,000 different causes. Sometimes that's caused by a communication failure. I'm still learning about those systems, CAN and class 2. They can be a real PITA even for seasoned techs to diagnose. Could be a cluster failure, too. That was common on the GMT-800 models, but has seemed to improve with this generation. Doesn't mean it won't still happen - just that the chances of it happening have gone down a bit.

 

You would need to have a breakout box hooked up to the DLC to see what is working and what isn't. A scope on the comm lines would see the problem immediately if the problem is communication. Even some mechanics don't own either one (I don't yet - very pricey, and I tend to turn these kinds of jobs down for my own sanity), so I don't expect you to have either one.

 

Isn't much help I can offer over the net, aside from some advice - do some research on shops reasonably close by that specialize in electrical troubleshooting. Read reviews anywhere you can. Even Google Maps. Talk to people anywhere you can as well, and see if one particular shop is recommended above others. Steer clear of the dealer, and all will be well.

 

If you're in western or central PA. or western NY, I know of a few guys out that way that could competently fix this issue for a fraction of what it would cost you going to a "parts changer". I'll say it again - stay away from the dealer.