My wife's 2003 TrailBlazer's transmission seemingly stopped transferring power to the rear wheels. A two truck driver took the TB to AAMCO to check it and they said nothing is wrong. They said they found out the 4x4 switch was in the 2-HIgh position and when they switched over the car was in gear. We've had problems with the transfer case going into and out of four wheel drive since we got the car but we lived in Colorado at the time and needed it for snow. We now live in Oregon and have used 4x4 maybe twice.

We also have had problems with the instrument panel pegging to the right, a warning dingaling signaling a problem and it clears up. The AAMCO people said they'd check the transfer case and let us know. They rebuilt the transmission when it died this past Feb but the car has 247,000 miles on it. It has been a virtually flawless car since we bought it other than the 10-12 times the transfer case went into 4WD and out.

Any ideas?

I would check the bcm. That is the actual control device. That would also effect your gauges.

Had something similar happen to our '03 Bravada.

The transmission tech did some kind of "dance" involving disconnecting the battery and pumping the brakes three times which reset the computer. I wish I could tell you the exact procedure but I can tell you that whatever he did fixed the problem and it never returned.

Maybe an internet search would turn up the exact steps.

quote Originally posted by Tstang429: I would check the bcm. That is the actual control device. That would also effect your gauges.

I should have insisted they check the BCM per your recommendations!

AAMCO charged us $1200 to remove and check the transfer case, couldn't find anything wrong, flashed the BCM and the TrailBlazer seems ok. I still dont' trust it to take my wife 130 miles roundtrip to Eugene, OR for chemo so I use my trusty 2008 Grand Prix. The part that ticked me off is that I told them to first flash the BCM before disassembling the transfer case but of course, the customer is always stupid so they flashed it later. I wonder if they even removed the transfer case.

[This message has been edited by starlightcoupe (edited 08-04-2016).]

Need advice. We're still getting weird symptoms from the dash and I am not happy with the way the tranny shifts after doing a total rebuild or replacing with a rebuilt tranny. Sometimes hard, other times a tendency to slip from one gear to another while upshifting--sort of like a set of worn clutches. The last time we took the car to AAMCO, they charged to remove, disassemble and reinstall the transfer case plus flashed the BCM and charged us $1300. We've spent more than $4800 on this "repair" and we're still reluctant to take the car for a long trip. It has 245,000 miles and everything else is fine with the TrailBlazer. Engine runs like a new one. I had good luck with AAMCO in the past in Colorado and Texas but here in BFE, they throw labor and parts at a problem until they finally discover something. My wife leans toward a new car but I don't want to spend the dough for a new one and she doesn't trust used cars.

Would a call to the corporate AAMCO do anything other than they punch my TS card? Any suggestions???

I know the Trailblazer is different than my Sierra, but a common problem on the Sierra is the 4WD selector switch goes bad. It's just a variable potentiometer (push button, in my case) that changes resistance to tell the BCM what mode to put the 4WD in. The switches are cheap and easy to replace. Probably the hardest part is getting the switch out of the dash. I'd double check that it's the same for the TB, but it might be worth a look for a cheap fix.

Here's the setup on a Silverado/Sierra:

Warning, he does have a foul mouth.

A Google search makes me think the 4WD switch and actuator are both common problems on the TB.

[This message has been edited by Formula88 (edited 09-19-2016).]

Thanks for the info. The switch for the TB is a multi-position rotary but I am sure it does the same thing as the pushbutton on the big daddy to my TB. I'll do some googling and see if the TrailBlazer has similarities in problems.

I drove the TB yesterday for about six miles and I didn't see any problem with it. When my wife drives, it exhibits the shifting problems. The dash died on us (she was driving) but was resurrected when she turned off the ignition and turned it back on when we stopped. Coincidence? I don't think my six mile trip was long enough to show anything conclusive. I feel like we're back to one car again. Luckily, we still have my 2008 Grand Prix that she doesn't like. I see a new car coming for her. Not good--we own cars and house outright and I don't want to go back into debt for a repair that could be simple.

I have an '03 Trailblazer that I bought 3 years ago July.

Zero issues with the transfer case, but I have had issues with the gauge cluster.

Tach didn't work 99 % of the time. Last summer the oil pressure gauge pegged itself hard to the right.
Eventually resolved itself. This March on a road trip, the speedo started climbing after about an hour on the road.
Was reading about 100 mph when we were really travelling about 65 mph. When I shut the engine off in a parking lot, it stil read 25 moh standing still.
Turns out there is a problem, with some crappy stepper motors, in the instrument cluster on a bunch of GM vehicles from 2003 to 2006.

Two solutions. Either find a 6 pack of these new stepper motors on Amazon for about 40 dolars, and get out the soldering iron, or get lucky like I did and found a used cluster a guy had for sale on the local area Classifieds, for 40 dollars and swap it out. Pretty easy to do. About a dozen screws and 3 electrical connectors. Two on the outer trim, and only one on the cluster. Good as new, and now I have a functioning tachometer again.

------------------
Marko.

'85 SE 2M6 Muncie 4 speed.
a.k.a "The Rumble Seat"

quote Originally posted by Marko: I have an '03 Trailblazer that I bought 3 years ago July. Zero issues with the transfer case, but I have had issues with the gauge cluster. Tach didn't work 99 % of the time. Last summer the oil pressure gauge pegged itself hard to the right. Eventually resolved itself. This March on a road trip, the speedo started climbing after about an hour on the road. Was reading about 100 mph when we were really travelling about 65 mph. When I shut the engine off in a parking lot, it stil read 25 moh standing still. Turns out there is a problem, with some crappy stepper motors, in the instrument cluster on a bunch of GM vehicles from 2003 to 2006. Two solutions. Either find a 6 pack of these new stepper motors on Amazon for about 40 dolars, and get out the soldering iron, or get lucky like I did and found a used cluster a guy had for sale on the local area Classifieds, for 40 dollars and swap it out. Pretty easy to do. About a dozen screws and 3 electrical connectors. Two on the outer trim, and only one on the cluster. Good as new, and now I have a functioning tachometer again.

I am beginning to think the problem with my TrailBlazer is the 4WD selector switch. I have severe back problems and dread pulling out the dash to get to the selector switch but it has to be done. We had three more iterations of the problem and moving the selector switch from two wheel drive to four wheel drive cleared up the problem. We spent nearly $4500 for "repairs" on tranny and transfer case. The tranny was beginning to slip from 1st to second and it needed work so hopefully AAMCO did the work they told had been done. If the problem isn't the switch then it may be the electric motor that selects the mode (2H-4wheel AOD, etc) but AAMCO said they removed, inspected and reinstalled the transfer and reflashed the BCM and found nothing wrong. I don't believe any of it.

I like the TBlazer and this is the first problem we've had in 260,000 miles. Engine is still strong and everything works as new. Showing its age but being retired, I don't miss a car payment in the least.

Pulling the TB dash bezel out is not that difficult. There are some hidden screws at the bottom of the bezel. You have to remove the kick panel, and there are (IIRC) a couple more under the HVAC controls, where the lighter socket is.

BUT... Do you have an aftermarket iPod adapter? If so, remove it. It plugs into the harness between the radio and the harness connector. I have had two different GM trucks (a Silverado and a Trailblazer) exhibit "ghost in the machine" electrical issues, that completely went away when I removed those adapters. They can "noise up" the CANBUS, and can cause the BCM and PCM to not communicate or to become "confused".

If you don't have an iPod adapter, still try unplugging and replugging the harness connector on the back of the radio.
I have a friend who did body work in a GM dealership, and he said he has seen several instances of GM radios causing the CANBUS to get confused.

What were my symptoms?

The Trailblazer...
My wife looked out one night and saw the interior lights on. Later on, they were off. Doors were locked. (I thought she was hallucinating.)
Months later, I hit a bump and all the gauges went to zero. Came back a few seconds later. A couple of days later, the battery was dead. When I went to jump it, nothing would work correctly. The engine wouldn't start. Power windows wouldn't work. All sorts of bizarre electrical stuff. When I unscrewed the radio and started moving it around, everything miraculously cleared up. Removed the iPod adapter. Never another problem as long as I owned it.

The Silverado...
The cooling fans wouldn't turn off. Had to disconnect and reconnect the battery.
The radio stopped working. Then it resumed. The dash lights would work, and then they wouldn't. The radio lights would work, and then they wouldn't.
Remembering the Trailblazer, I removed the iPod adapter. Haven't had a gremlin since. That was like 2 years ago.

[This message has been edited by Raydar (edited 10-30-2016).]

Raydar, I didn't see your post until tonight (long after you posted it) and I wish I had kept watching this thread. Your symptoms with your TrailBlazer are exactly like mine with respect to ghostly happenings. I don't think our TB has an IPhone adapter but I will do all the other things your mentioned. We had a couple of other weird things happen recently that cleared up with I stopped the car, switched everything off, started the engine and drove home with no problems. A loose or partially corroded connector can cause such problems but with my back, I can't do much more than "stupid-vise" someone else.

Thanks for your advice!

Edit: I removed the bezel awhile back when we lived in Colorado to repair the instrument panel. We were having odd things with the car before and after the work.

One of the weird things taught me a lesson. I used the TB to drive from Colorado Springs to Houston with my brother along who had Alzheimer's and both of us had to pee. I left the motor running while both of us relieved ourselves on the side of the freeway (it was around 4am) and we couldn't get back inside the car because the driver's and passenger doors were locked. Neither of us pressed the lock switches when we exited. I was ready to break a window when I tried getting in the rear doors and back hatch and found only the right rear passenger door unlocked. I learned to leave a door open or have another set of keys (I have two extra sets now) when I exit a TB.

Bro passed away a couple years later but talked about the time we peed on the freeway and nearly had to walk back to The Springs.

[This message has been edited by starlightcoupe (edited 11-26-2016).]