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2002 chevy trailblazer_lt_ext
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Discussion Starter · #1 ·
Hello, I will try and explain best I can. Last winter I was having troubles with my 4wd when it was cold. Sometimes it would work when I would drive for a while, but when it wasn't working the 4wd switch lights were off. They would blink momentarily when starting they go off. After making it through the winter, it finally quit working. Using the information off several posts on this site, I decided to pick up a TCCM from the local junkyard. This worked, never had another problem for a year. Now with winter approaching of course. Issues with the 4wd. I noticed it last weekend during our first snow. I put it in A4wd and it seemed to be working, then the service 4wd light came on. The position light seemed to be stuck on A4wd until I shut it off, and started it again. When trying 4wdhi it seemed to work. Now, a week later, and reading many similar posts, I just tried to turn it to 4wdhi and I heard the noise like it was trying to engage, but the service 4wd light came on and the the dash switch sat there blinking on 4wdhi. I turned off the vehicle and turned back on leaving it in 4wdhi and the service light came on right away and no lights on the dash control. I turned the vehicle off again, turned to 2wd and the service light came off and dash switch was lite normally on 2wd. Tried to pull fuse 8 (TCM I think) put it back in. still the same. So basically I have not 4wd. Seems to be stuck in 2wd. My cheap OBDII reader doesn't work with these codes. I have seen comments of ecoder motor and actuator. Or should I be looking to a another TCCM. Or should I see what kind of codes come back from the service 4wd light?

Thanks in advance!!!
Ryan
 

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2003 gmc envoy_slt_xl
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325 Posts
This is not the TCCM, but rather problems with the transfer case operation itself. The transfer case is not operating properly, the TCCM is sensing this, hence the service light on your dash. If the TCCM was dead (as you had before), you would have the symptoms that you had previously.
 

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2003 gmc envoy_slt_xl
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325 Posts
I am not sure if a scan would narrow down the problem, but it couldn't hurt. Try some searches in here about transfer case repair, to see if there is anything that you could service yourself. I haven't done that, and hope that I don't have to.

I believe I remember some replacing their encoder motor, but again, I haven't done that.
 
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