2008 Chevy Avalanche ltz gages,locks going crazy

[DAMIEN SEAY]

My 2008 chevy Avalanche ltz won't start sometime and when it does the gages and door locks go crazy. I have saw videos on YouTube on how to fix the problem but still dont work. I have replaced the battery, alternator, starter,ignition switch,  negative battery cable,  pcm, bcm, added extra ground wire to the ground strap from the motor, replaced fuse box inside the truck, replaced all fuse in junction box under the hood, replaced ground wire from the hood. Still same problems. A friend told me to try replacing positive cable and cam shaft sensor. Need help asap

[Jsdirt]

Holy parts cannon. Stop replacing parts on that one. You need to check over EVERY ground on the vehicle, specifically the ones around the engine and under the cab. I would remove and clean every single ground connection. From there you'll need to inspect wiring harnesses for chaffing, melting, or complete rub-through. From there check every connector - start with the easy ones, and work your way toward the harder ones. I'm betting there's either a bad or missing ground, green pus in a connector, or a broken wire hidden inside intact insulation.

 

Check the ECM and BCM for powers and grounds - make sure they're all good right to the modules. Make sure no pins got bent during the BCM swap, and make sure there are no bent pins on the ECM connection as well. This one will try your patience, but without service info, this is the only way to get it done.

[mjm-1957]

Does this vehicle have any aftermarket remote start or alarms added to it? First place I would be looking at  if anything was added on. They are usually poorly installed and the components are garbage.

[Jsdirt]

^^^ Yep, what Mike said. ^^^

[DAMIEN SEAY]

No. 

[DAMIEN SEAY]

Truck was running fine until the temperature fell below 32 at the first of November. 

[mjm-1957]

There a couple of older bulletins similar to what your describing. I can't figure out how to send a link but the actual bulletins are PIT4730B,document ID #4902455 and the other one is 08-07-30-021H document ID#4213654. They have a lot of good information in them about no start conditions and door locks cycling with gauge cluster problems. Hope you can get access to them. Don't throw anymore parts at this. Its probably a backed out terminal or an intermittent short to ground taking down the high speed lan. Good luck.