4WD Problems - '03 TrailBlazer
Hi all: I've had troubles with the 4wd on this vehicle since I purchased it new. While it was still under warranty the dealership replaced the transfer case and the switch for problems on two separate occasions while it was less than a year old. Since then, the 4wd has worked, however, it makes a loud humming noise while driving in 4wd. Here's the problem now and I'm not sure what to believe or do next. When it started snowing here this Winter, the first time I selected 4wd, my service 4wd light came on and all the lights on my selector switch would go out. If I turned off the car and restarted it, I would have no lights on the selector and the Service 4wd light would still be on. I could not switch it to 2wd. When this happened I took it to a local mechanic who replaced the transfer case encoder motor. I drove it home that day in 2wd and subsequently drove it in 2wd as we weren't really getting snow. I switched it to 4wd to test it and back again and all seemed good. The next time we got a significant snow storm the problem came back, no lights on the selector switch, service 4wd and can't switch out of 4wd. If we take the #8 fuse out, we can switch it to 2wd. I took it back to the mechanic who replaced the motor again. Problem persisted. He then told me "it's the transfer case". I replaced the TCCM with a replacement I purchased online, same part number, from a 03' Trailblazer. Problem exactly the same. Thinking I may replace the selector switch next but mechanic thinks it's the transfer case itself that's needs to be replaced. Already sunk $650 into motor replacement and hesitant to go with the transfer case replacement as the mechanic wasn't correct with that diagnosis. Thank you in advance for any ideas!