2005 Chevrolet Colorado 4dr Crew Cab ZQ8 LS Base Rwd SB (3.5L 5cyl 4A)
The Chevy Colorado is an electrical nightmare. If you are considering buying this truck, leave the dealership immediately, and go buy a horse. This truck is complete garbage. The blower works, sometimes, the lights work, sometimes, the radio works, sometimes, and its all stems from GM having a terrible electrical system. I have read forums with people having these issues with the Colorado of any year. So, GM obviously doesn't care enough to fix the issues their vehicles have considering the electrical systems they install have been worthless for over a decade with no recalls. I would recommend buying from any other manufacturer.
Scrap the entire electrical system and install a gerbil in a wheel. It would be more reliable.
"The blower works, sometimes, the lights work, sometimes, the radio works, sometimes," =
I had these same issues with my 2005 Colorado. Its a ground issue GM put grounding blocks on the side panels under the hood. This issues you are having are controlled by the grounding block on the passenger side. just behind the air filter take out the grounding block and ground everything right to the body. Problem fixed.