Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 6 of 6 Posts

·
Registered
2002 gmc envoy_sle
Joined
·
3 Posts
Discussion Starter #1
Hello, all. This my first post to the Trailvoy Forums. I searched through other threads that seemed related, but I couldn't find the info that I think that I need.

I have a 2002 Envoy SLE that I just purchased used. It has 234,000 km on it (about 144,000 miles). When I purchased it, it had the check 4wd light lit. Before purchasing it, I took it to a trusted garage for a pre-purchase inspection, and they said that the problem often is just the transfer case motor. Currently, the transfer case is stuck in 2wd mode.

Well, I ordered a replacement motor and tried to install it today, and I ran into a problem: The splined shaft coming out of the transfer case is rotated a little to far for the replacement motor to go on and have the bolt holes line up. I tried to rotate the splined shaft with a pair of pliers (padded to prevent damage to the splines, but it won't move (it has a little play, but not nearly enough to get it where I need it to be).

I figured that I would see if the motor would shift at all plugged in to the wiring harness, but not bolted to the TC, and it won't move when I move the 4wd knob.

When I start the vehicle, all of the lights next to the different settings of the transfer case knob flash except for the 2wd light and the N lights up, and then all of the lights turn off.

From what I've read here, it sounds like the TCCM is probably bad, but I am a little worried about not being able to manually shift the transfer case by rotating the splined shaft. Is this a problem with the transfer case, or is this normal behaviour?

Before I go and order any new parts, I would like to get a better diagnosis so that I only order what I need...

Thanks,
-Chris
 

·
Banned
2004 gmc envoy_sle_xl
Joined
·
1,239 Posts
It is true that the 2002 TCCM are known to go bad, and replacing it with a 2003+ unit is advised. Since you don't know the maintenance history of this truck and one of the critical maintenance items is the transfer case fluid change every 50K miles. it might pay for you to open the fill plug on the TC and see if there is any fluid in it.
The splined shaft should be able to be moved by hand, since the actuator motor is not a high torque unit. You may have a toasted TC.
Also, you may want to try going to G M T N a t i on . c o m (no spaces), all the experts from here went there.
 

·
Registered
2004 chevy trailblazer_ltz
Joined
·
17 Posts
Just an idea, do you have all 4 wheels off the ground when trying to turn the shaft by hand? Maybe even have an assistant spin some wheels while you try to turn the shaft. May be just bound up.

Sent from AutoGuide.com Free App
 

·
Registered
2002 gmc envoy_sle
Joined
·
3 Posts
Discussion Starter #4
Thanks for the fast responses! I should correct my initial post slightly, although I don't think that it makes a difference. When I start the car, all of the lights on the TC control knob turn on, including the "N" lighting up red, and then they all turn off after about 2 seconds.

I'll put the vehicle up on 4 jackstands and see if I can shift the TC by hand with someone there to turn the wheels for me. I'm pretty sure that the front end is ok, since it drives well in RWD (2HI), but I should be able to turn the driveshaft to the front diff to check that that is ok, too.

When I drain the fluid, is there anything that I should look for to see if the fluid is really old? I couldn't see anything in the Haynes manual about the kind of fluid that I need to put into the TC, either, so that info would be really helpful.

Also, if it comes to it, how much of a pain in the a__ would it be to install a new transfer case without a hoist, just jackstands?

Thanks again,
-Chris
 

·
Registered
2004 chevy trailblazer_ltz
Joined
·
17 Posts
Not sure about your year, but my 04 takes auto trac 2 fluid. Blue fluid only available from GM. The transfer cases are not too bad to replace. Unbolt both driveshafts, remove all bolts and slide straight back. Just have to be careful not to damage the seal between the trans and transfer case.


Sent from AutoGuide.com Free App
 

·
Registered
2002 gmc envoy_sle
Joined
·
3 Posts
Discussion Starter #6
Hey, thanks for the info. It's good to know that replacing the T-case won't be a nightmare if it comes to that. Now that I think of it, when I purchased the vehicle, the lady said that the 4wd worked, but her mother (it was her vehicle) didn't want to pay the $100 for GM to do something to turn the warning light off... I wonder if she meant getting the TCCM reprogrammed.

Regardless, given the cost of a replacement vs "reprogramming", I'll just get a replacement one.

That brings me to my last question, and then I'll be ready to buy some parts! I've been looking for a TCCM for a 2003 Envoy or Trailblazer, as I've been told that the "issue" with the TCCM was fixed after 2002. However, when I look for these, I see several different GM part numbers. Will any 2003+ Envoy/Trailblazer TCCM work with my 2002 Envoy SLE, or do I need to avoid certain models?

Thanks again, and I'll be certain to post my progress!
-Chris
 
1 - 6 of 6 Posts
Top