Four problems related to wiring have been reported for the 2005 GMC Canyon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 GMC Canyon based on all problems reported for the 2005 Canyon.
Air conditioning stopped working on fan positions 1,2, and 3 and works only on 4. Eight pages of complaints indicated that faulty components were put into truck at factory and should be recalled: blower motor resistor, wiring harness and poor ground wire. Ac delco part 15-80521 one part requiring replacement.
The plug that controls the hvac has shorted out causing burn marks in the inside of the connector. This causes the blower to only work on the highest setting (number 4). I had to replace the resistor - p/n 15218254, connector - p/n 15306069, and the wiring harness - p/n 89019124. I am not sure how many times this has been reported, but it might not be a bad idea to check out coloradofans. Com. There has been complaints spanning back to 2005 up to today about this.
The resistor in the fan kept burning out and had been replaced. Finally it was determined that the wiring harness was malfunctioning and required replacement. I believe this is a known defect, yet nothing was done by gm.
Air conditioning fan abruptly stopped working on all fan speeds except "4", the highest position. Checked internet for possible solutions and found that there have been numerous failures exactly like mine. All involved the "blower motor resistor assembly, connector and/or wiring harness" shorting out. Scortching the connectors, resistor assembly and causing the plastic to melt/burn. Gm parts at local dealership had replacement parts and I was able to resolve the problem. Speaking a gm service advisor, he confirmed that there are numerous repair problems with these parts on the GMC Canyon/ Chevrolet colorado 2004-2007. But no explanation for why they are failing. Numerous internet reports with photo's showing damage and explaining problem most requiring multiple or repeated repairs. Old parts are available.