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2003 gmc envoy_slt
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38 Posts
Discussion Starter #1 (Edited)
Hey guys,

I've been having this issue for a while now. When it get's really cold 30 or below, I can never engage 4wheel drive and the 4x4 service light comes on.

The symptoms are: When I use the selector switch to change the 4x4 setting, the selector switch light blinks then goes out and the service light comes on. If I warm up the Envoy for a while, the service light will turn off, but the selector switch light will also stay off regardless of the position/selection. I also do not hear the encoder motor moving. At this point, the 4x4 is not engaged because I can't feel the normal 4wheel engaging and the just the rear wheels slip on snow/ice.

I've tried the moving the selector switch back and forth 30 times and pulling the fuse and get the same issue are recommended by the Sticky thread.

When the temps warm back up to 45 or so, the 4x4 changes fine without any issue. I don't really drive the Envoy much so I haven't really looked into it that much.


I found a thread from a long time ago, and the person solved the problem by replacing the TCCM. I'm thinking this may be the same issue.

https://forums.trailvoy.com/showthread.php?t=80369

What do you guys think? I can get a TCCM for around $50 used on ebay. Worth a shot?
 

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2003 gmc envoy_slt
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38 Posts
Discussion Starter #3
Yes, I've changed the TC fluid on the set scheduled. Last changed was maybe 35k miles ago.
 

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2004 gmc envoy_slt
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2,415 Posts
Without having access to a high end scan tool, which would allow you to see the actions of the 4x4 system, replacing the encoder motor on the TC would be recommended.

You say you can't hear the encoder motor when switching modes, can you hear the front disconnect actuator?
 

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2003 gmc envoy_slt
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38 Posts
Discussion Starter #5 (Edited)
Without having access to a high end scan tool, which would allow you to see the actions of the 4x4 system, replacing the encoder motor on the TC would be recommended.

You say you can't hear the encoder motor when switching modes, can you hear the front disconnect actuator?
When I make the selection switch, I really can't hear anything moving. It may be due to engine noise but I can't here the encoder motor or actuator move. I may try replacing the TCCM first and see if that's the issue. I've seen them on ebay for around $30 tp $50 so it would be a cheap cost. I've heard the 02's are generally the year with TCCM issues however, mine only has issues when it's really cold outside, so I'm wondering if the electronics fails to work at low temps.
 

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2005 chevy trailblazer_ls
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15 Posts
It doesn't have a Block heater does it? that could help. I remember reading about someone having an issue with condensation freezing the vacuum line.
 

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2003 gmc envoy_slt
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38 Posts
Discussion Starter #8
A block heater only affects the engine block, has no influence on the transfer case or transmission.
I'm not sure if it has one or not. I've ordered a used TCCM from ebay that came of an 04 so hopefully it will resolve my issued. I was able to use the 4x4 this past weekend when the temperature was about 45 and had no issues.
 

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2003 gmc envoy_slt
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38 Posts
Discussion Starter #9
I got a TCCM off ebay and installed it a few weeks ago. I worked fine after the install but the temp was 55 degrees. I waited until a cold morning, below 32 decrees to test and it failed again with the same symptoms.

I'm going get a new TC encoder shift motor and see if that will solve the problem. It will most likely not be soon because this is my second car that I use when hunting and fishing so 4x4 is not really needed that much.

I'll update after I install the new encoder motor and test. Does anyone have any feedback on the motor manufacture? (Dorman, Cordone, used off ebay?)

Thanks,
 

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2004 gmc envoy_slt
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2,415 Posts
The engine does not need to be running to operate the modes of the 4x4 system. When switching between 2HI and 4HI, you should be able to hear the encoder and front actuator.
 

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2003 gmc envoy_slt
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Discussion Starter #11
The engine does not need to be running to operate the modes of the 4x4 system. When switching between 2HI and 4HI, you should be able to hear the encoder and front actuator.
Yup, that's correct. At first I always thought the engine had to be one, but the key only has to be in the ON position (engine off) to switch the 4x4 settings.
 

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2005 chevy trailblazer_lt_ext
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83 Posts
When you change the transfer case fluid, are you using the GM Autotrac II? It is a red fluid.
 
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