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2006 saab 9_7x
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450 Posts
When was the last time the transfer case fluid was changed? Needs to be changed every 50,000 miles with only AutoTrac II. Aavailable at the dealership and some auto stores.
 

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2003 gmc envoy_sle
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2 Posts
So I've read all the posts on this topic and here's where I am at. I confirmed with jiffy lube that all my fluid levels were good as of November when they changes oil. I couldn't switch into anything except 2whi. After some wonkiness, all 4 lights would flash then service 4wd light comes on. Two nights ago, its been real cold, like single digits, I go to drive, usually flashing and service light behavior....I start driving and can feel 4wd is on while turning and the gearing is different. I turn onto a side road and almost have no power, things are spinning but minimal power. I restart the vehicle and both the 4wlo and 2hi lights are on, the switch is on 2whi. I drove back home and it seems to be stuck in 4wlo now. I drove slowly to the store where I was going and could hear 4wlo doing what it does....some diff whining... I put in neutral and it tries to move back to 2whi....but when I gave it gas, it was still 4wlo, but without power again. Fiddled some more and did the neutral thing again and I heard it again trying to go back to 2whi. This time but worked and the light above 2whi is on and the service light is off. I plan to eBay the tccm, as this is what seems to be the problem. The fluids are good, the motors are moving the transmission....thoughts?
 

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non_gmt360 trailblazer_lt_ext
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241 Posts
So I've read all the posts on this topic and here's where I am at. I confirmed with jiffy lube that all my fluid levels were good as of November when they changes oil. I couldn't switch into anything except 2whi. After some wonkiness, all 4 lights would flash then service 4wd light comes on. Two nights ago, its been real cold, like single digits, I go to drive, usually flashing and service light behavior....I start driving and can feel 4wd is on while turning and the gearing is different. I turn onto a side road and almost have no power, things are spinning but minimal power. I restart the vehicle and both the 4wlo and 2hi lights are on, the switch is on 2whi. I drove back home and it seems to be stuck in 4wlo now. I drove slowly to the store where I was going and could hear 4wlo doing what it does....some diff whining... I put in neutral and it tries to move back to 2whi....but when I gave it gas, it was still 4wlo, but without power again. Fiddled some more and did the neutral thing again and I heard it again trying to go back to 2whi. This time but worked and the light above 2whi is on and the service light is off. I plan to eBay the tccm, as this is what seems to be the problem. The fluids are good, the motors are moving the transmission....thoughts?
there is another site where there are always guys to help.. ones that have been wrenching on these trucks since they first came out.. check out the link here.. http://bfy.tw/3Ttk there is tons of info on the 4wd system over there.. :)
 

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2005 gmc envoy_denali_xl
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1 Posts
4 wheel drive not working at all

I have a 2005 envoy denali xl with 4 wheel drive issues. I have no service 4whl drive light on the dash. The selector lights up to whatever position I want... 2hi, 4hi auto, 4 hi, or 4 lo.
But that is all. Only a 1 wheel wonder.
The tranfer case and the actuating motor have been replaced(with used).
I am going to try unhooking the battery when I wake up, and then pull #8 fuse, maybe that will reset the control module.
Any other ideas of what to check???
 

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2006 chevy trailblazer_lt
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1 Posts
Help with checking 4X4 out

Okay, I have read ALOT of post on 4x4 issues on here. There seems to be alot of conflicting advice.
Here is my issue and what I have done so far.
My front end disconnect went out, actualy it broke. So I changed that out, and what fun that was, put in a new cv axle as well both sides. All seemed to work fine. Fast forward 7 months and the first time I went to used the 4x4, only the back tires spun. I here the high pitch whine from the front, and a lower whine from the tc. Still nothing. The actuator in the front moves in and out ( had it off the front end disconnect and saw it move). Just by chance I pushed in the "plinger" on the disconnect and turned the pass wheel, felt like something wasn't catching. Next I jacked up both sides and had it in 4hi pushed in the plunger again and turned the tire, the other didnt spin at all. Could it be a bad disconnect?
Going to change the tc fluid tomorrow just for giggles and its time.
Any other checks I can do???????
 

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2006 chevy trailblazer_ls_ext
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1 Posts
2006 Chevrolet Trailblazer 4x4 Issue

I have read your post and am having Issues with the 4x4 on my 2006 Trailblazer LS Ext 4.2. I used my 4x4 about 2 weeks ago with no issues. Last weekend I installed a rough country leveling kit, new control arm brackets, tie rod ends, and upper and lower ball joints. This week it has sleeted or had freezing rain 3 times lol and no 4x4. I have read your guide and ordered an actuator, but want to give you the details to see if you agree. When I shift into 4hi, I can hear a distinct noise but I do not hear two noises (might be that my hearing is not perfect). I believe the noise I hear is the transfer case actuator. I am positive that it is working as the light functions correctly and when I shift to 4lo I am in low range but missing the traditional binding of it being in 4x4. In the past if the tires had not rolled far enough to engage there would be a clicking from the front requiring backing up to engage the wheels. This is not present.
 

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2003 gmc envoy_sle
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2 Posts
So I've replaced the selector switch and the tccm and I still have the problem. Its stuck in 2hi, so its drivable at least. After a few weeks, the lights went out and the selector light said 2hi. First I switched the tccm out for the $40 one I got from eBay. I had to try it so I switched to awd and the light switched. I then went to 4hi and the light blinked then settled on 4 low. I backed out of my snowy parking space, rear wheels only engaged. Turned out of the parking lot and nowbits acting like its in 4lo. Diff whine from front axle. I got to switch back to 2hi, by going into neutral. Went and purchased the dkrman reman tccm and a switch. Switched switch first. When I started up the engine no service 4wd and the selector light settled on 2hi. I moved it to awd no problems, turned to 4w Hi and it went to 2hi and service 4wd came on. Replaced the tccm, started up right to service 4wd and no lights on switch. And that's how it is now. So its got to be ?
 

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2006 chevy trailblazer_ls
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9 Posts
One More Step That May Help

:) Please read me before making a post. :)

There seems to be quite a lot of mystery to newer folks when their 4x4 functions stop working. Since crappy weather season is upon us a lot of people are trying their 4WD functions for the first time this year... and discovering all isn't as it should be.

Here's my attempt at a troubleshooting checklist/flowchart. Hopefully this helps folks get a handle on what's wrong with their setup and how to fix it.

Information in this thread applies to 360/370 trucks with selectable 4WD functions (TrailBlazers, Envoys, Ascenders?). Trucks with non-selectable AWD (Rainiers, 9-7s, Bravadas) may find some of the information here useful. However AWD trucks lack some of the parts discussed here.

On to the show.


Gah! My 4WD doesn't work! What do I do?

Is the Service 4WD light on?

Yes: Go to Section 1.

No: Go to Section 2.



Section 1: My Service 4WD light is on.


Are there any lights lit on the 4x4 selector switch?

Yes: Go to Section 2.

No: Try these steps.


  1. With the ignition off, rotate the 4x4 selector switch from left (2HI) to right (4LO) and back again about 20-30 times. With lack of use, the contacts inside the 4x4 selector switch can get a light amount of oxidation on them. Repeatedly rotating the switch can sometimes clear this problem up. If this doesn't help, read step 2. If step 2 doesn't work for you, replace your 4x4 selector switch. If replacing the 4x4 selector switch doesn't work for you, try to find a local member with a verified working TCCM to swap in. If the problem goes away, return your friend's TCCM and buy a replacement for yourself. Search these forums for replacement instructions.

  2. On some 2002 model year trucks, the Transfer Case Control Module (TCCM) can have trouble waking up when the engine computer tries to talk to it. Fuse #8 in the engine bay fuse block provides power to the TCCM. Pulling this fuse and replacing it will usually wake the TCCM up and allow the use of 4WD for a time. Fixing this requires either a dealer software update (can be spendy, doesn't always work) or replacing the TCCM with a unit from a 2003 or newer model with selectable 4WD.


Section 2: Checking the motors.

With the ignition on, switch the
4x4 selector switch from 2HI to 4HI. You should hear two distinct mechanical whirring sounds. One from the middle of the truck (under you) and one from the front of the truck.

I hear both whirring sounds:
Go to Section 3.

I don't hear the sound from under me: There is an issue with the Transfer Case Encoder Motor. Check the connector going to the motor(cylinder looking thing) on the transfer case for damage/corrosion. The motor may require replacement.

I don't hear the sound from the front: There is an issue with the Front Axle Disconnect Actuator. It is plugged into the Front Axle Disconnect (AKA Splined Disconnect) located under the truck on the right side of the oil pan. Check the connector attached to it for damage/corrosion. If the connector is OK, replace the actuator.


Section 3: Identifying mechanical failures.

Turn the ignition on but don't start the truck. Place the
4x4 selector switch in 4HI. Using a jack/jackstand raise the LEFT FRONT wheel off the ground. Try to turn that wheel by hand.

The wheel does not turn freely:
If you've followed the troubleshooting guide without skipping ahead and come this far, then you have an issue that is beyond the scope of this post. Possibilities are an intermittent problem in the
Front Axle Disconnect, front differential failure or transfer case failure. I recommend you make a post in the 4x4 section detailing each of the steps in this guide you just followed. Also note any noises you may be hearing while driving in and out of 4WD.

The wheel turns freely:



  1. Crawl under the truck so that you can see the front driveshaft. Have an assistant turn the left front wheel by hand. Can you see the driveshaft turn? If so, you have an internal transfer case failure. Most likely due to worn out clutches. If not, proceed to step 2.

  2. It is likely your Front Axle Disconnect is not engaging properly. This can be caused by worn bearings or a broken shift fork. You can check for worn bearings by grabbing the inner tripot joint(closest to the Front Axle Disconnect) of the right side axle and trying to wiggle it. Movement indicates worn bearings. Even if your bearings aren't overly worn, there is a possibility of a broken shift fork, spring, or other components.

    There is a great guide on the teardown and rebuilding of the Front Axle Disconnect here: http://www.offroadtb.com/articles/tech-docs/front-axle-4wd-disconnect

    There is an alternate way of fixing the shift fork issue here: http://forums.offroadtb.com/viewtopic.php?f=27&t=1227

  3. If you rebuild/replace your Front Axle Disconnect or are 100% sure it is functioning properly and still are at this point in the troubleshooting guide, you may have an internal front differential failure (likely) or broken intermediate shaft (extremely rare, couldn't find an instance of this by searching). Now is the time to make a post in the 4x4 section detailing all the steps you followed in this guide as well as any other observations made.


There you have it. I hope this guide points you in the right direction.

Additions/corrections welcome! :cool:


I had considerable difficulty removing the driveshaft until I removed one end of the connecting link between the lower control arm and the sway bar, then I finally had enough room so that it all came apart. By the way, I replaced my RH driveshaft this week because the US$ is up against all foreign currencies. My replacement was only $65, the cheapest list price I found was only $48.00. At those prices, my opinion is to throw the old one away or keep for spare.
 

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2004 gmc envoy_sle
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I did all those things mentioned and everything seems to be fine? But everytimw i turn 4hi on and then back to 2 hi thats whem it kicks the service light on drive the truck a few times shut it off a few times it will start working again?????
 

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2006 chevy trailblazer_lt_ext
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I'm hoping to get some feedback

I had the service 4x4 light on I read to change the encoder motor and use at delco as aftermarket may not work. I changed the encoder actuator. I turned my car on and was excited no service light anymore! Womp womp womp, turned it to 4hi and it stuck in 4auto.
I have pulled fuses in the engine compartment as well as under rear drivers seat. Disconnected the battery for 30 min as well. I flip the ignition forward and turn the selector and hear no noise when moving it the light stays in one spot. When I turn the ign on I do hear a noise (same noise I hear when taking fuse 8 out in the front of the car) but not sure if the noise I hear in the rear/under the car is for that or the fuel pump.
Every few times I turn the ign forward I hear the motor when flipping from 2hi to 4hi but not every time when the service light isn't on. But as soon as I switch the selector the service light comes on.
When I switch the selector to 4hi (it doesn't light up in that section) I turn the wheel and the wheel spins but not the drive shaft. When it is stuck in a4wd the wheel spins as well the drive shaft and makes a slight clunk noise. Being it won't slight up in the 4hi section I am not sure of what or where to go from here. Could someone give me some insight please?

This is a 06 trailblazer 4.2 lt ext

Thanks a bunch,
Lindsey
 

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2002 chevy trailblazer_ltz
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13 Posts
Replaced front axle disconnect actuator, still no work

So I followed the directions at the beginning of this thread. Transfer case motor works fine. Front axle disconnect actuator didn't make any noise. Pulled it and connected to a second TB I have . Still nothing; great, bad actuator, buy a new one. Install it and still no noise/motion. Take the new actuator to the second TB, plug it in and it works. Put new one back on first TB, still nothing. Connector/wiring look good, no damage/corrosion, wiring harness looks fine. What now? Is there a wiring diagram I can trace back? Bad fuse?
 

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03 trailblazer, service 4wd light came on after making a left hand turn. I did all the troubleshooting described in this post.

I have the indicator lights on the switch, i hear the encoder motor and axle actuator working (both are under a year old)

Jacked the front end up with it in 4hi and wheels turned together (but opposite directions)
Dropped the right side and the left tire doesn't spin freely...the shaft does move with the left wheel.

So what's next?
 

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2003 chevy trailblazer_ls
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Old thread revival: My '03 TB with 156K on it popped the "service 4wd system" light the other day along with no lights on any of the positions on the selector dial. Read the initial post for this thread, cycled the selector switch about 30x and just for kicks pulled fuse #8 and re-installed.

Problem solved :)
 

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2002 chevy trailblazer_ltz
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So I followed the directions at the beginning of this thread. Transfer case motor works fine. Front axle disconnect actuator didn't make any noise. Pulled it and connected to a second TB I have . Still nothing; great, bad actuator, buy a new one. Install it and still no noise/motion. Take the new actuator to the second TB, plug it in and it works. Put new one back on first TB, still nothing. Connector/wiring look good, no damage/corrosion, wiring harness looks fine. What now? Is there a wiring diagram I can trace back? Bad fuse?
Guess I never came back with the fix on this. Turns out the +12v wire going to the front actuator was broken 'somewhere', so no power to the unit. Tried to trace it back but why is the fuse/source in the panel under the back seat?? I gave up and ran another wire from a fuse in the engine compartment fuse block down to the actuator. Bingo, been working fine since.
 

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Weird rubbing sound when in 4wd??

Sorry if this has already been covered, couldn't find anything (please direct me if it has).
I have an 05 TB, well over 250k(I'm the 3rd owner and put something like 10k on her in the 3 months I've owned her) and my 4wd seems to work well, but I've noticed a weird rubbing sound from the front end lately whenever I put her into A4WD (usually just use 2HI, and haven't used 4HI or 4LO yet)
I wouldn't call it a grinding or clunking, really just sounds like something plastic rubbing against the front wheels or axle or something, but I've checked and there doesn't seem to be anything that could be rubbing... Any advice for this gal who likes to think she knows what she's doing, but really doesn't?
 
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