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2004 chevy trailblazer_lt
19 Posts
Discussion Starter #1

Thankfully, our winter weather is winding down here in Michigan, but I'm sure we'll still have a few days before I can officially retire A4WD for the season. Unfortunately, 4WD has been acting up on me and I'm not sure where to go. Searching through the forums, I'm convinced it's either the TCCM itself, or the TCCM Encoder Motor. I was hoping someone could recommend where I start.

2004 Trailblazer

Symptoms: I always keep the in A4WD

* Most time, 4WD works without issue

* I often hear a "crunchy", "grinding" sound when my car starts. Sounds like it's coming from the front driver side (encoder motor?)

* When Switching from A4WD to 2HI, I often see the light jump up to 4HI, then down to 2HI. I don't recall this happening before.

* Turning on non slippery pavement has (a couple of times) made it feel like I was in 4HI when I wouldn't expect to be.

* Service 4WD light came on and the lights on the selector switch went out

* Usually letting the vehicle sit for a few hours resolve all issues, but after use, it starts happening again. It has always been resolved by letting it sit over night, then it comes back the next day.

* It's colde here; ~20 F degrees. Colder if you factor in the windchill. It seems like the colder it gets the more problems I have.

My gut is telling me encoder motor because of the noise I hear when the car starts. I'm not sure an encoder motor would cause the lights on the selector switch to go out. It makes sense that it would, I just don't know for certain.

I don't have a garage, but I'm not a stranger to tearing my car apart in my driveway, in the middle of winter. I'd rather not if I don't have to (it's much more fun to tear apart in the summer!). Any tips to help me quickly figure out which part I should replace first would be greatly appreciated. The less time I'm on my back on the frozen ground the better! :)
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