I have a 2000 Silverado, the transmission is swapping to Tow/Hual on it's own. Sometimes it is in tow/hual when I start the truck and sometimes it will swap while driving. Any help would be appreciated.

 

Perhaps take it to a dealer, or talk to someone who has a high end code scanner, like a TechII factory Gm scanner, and have them look through the computer modules on the truck and see if they have any codes.

 

Before taking it to the dealer, I would suggest checking the wiring to the Tow/Haul button in the steering column. You may have a short to ground on the BCM side of the wiring. It's common for the wires to get pinched near the shift lever. If you don't find a frayed wire, then take it in. Otherwise you may be able to fix it yourself.

The Tow/Haul switch simply grounds the circuit momentarily. In-turn the BCM reads this signal and will command the IPC to turn on the Tow/Haul light. The BCM also sends a signal to the PCM which sets the transmission to the requested mode. Pushing the button again completes the same process except it turns off the haul mode.

 

It was a broken wire. Made repairs working fine now. Thanks for the help.