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2006 chevy trailblazer_ls
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Discussion Starter · #1 · (Edited)
This is a bit convoluted, so I'm going to try to explain this mess with bullet points:

* First issue was car would not switch back into 2WD from 4WD high.
If I turned switch, all the lights would flash quite a few times, then
it would go back to 4WD high and stay there. Car was actually in 4WD.
Replaced switch. Not the problem. Research here and elsewhere pointed
to 3 possible culprits: Front axle actuator, TCCM or encoder motor.

* Second issue was car would kick out of overdrive after 15 or 20 minutes
of driving 70 mph or more. No nasty trans noises, no clunky shifting, just
that RPMs would suddenly go from 2400 to 3000. No trans/shifting
problems with city driving. Only high-speed freeway driving. Research
here and elsewhere suggested 3 possible culprits: TCC (Torque Converter
Clutch) or TCC solenoid, TCM (Transmission Control Module) or PCM
(Powertrain Control Module).

Bad car owner/poor college student admission of guilt: drove car with these conditions for about 4 months. I'm poor. Poor people do stupid things that
eventually end up costing even more money. I knew that. :duh: Used up half the life of the front tires that were brand new.

Last week, my son pulled off the encoder motor to try to get the car back into 2WD. He was successful. Managed to crank the shaft by hand to shift the car back into 2WD. He was unable to get the splines/key to align to reinstall the encoder motor, so we figured the encoder motor was toast and just left it off for now. It worked like a charm. Car was in 2WD and stayed there.

* One week later, driving to school on e-way. Car kicks out of overdrive at
usual time. Backed off on speed as usual, but this time was different.
When I put my foot back on the gas, I had ?no drivetrain engagement?
The engine just revved, no forward motion. Nothing in any gear, forward
or reverse. Called tow truck and towed to shop.

At this point the drivetrain was not engaged. We were able to push the vehicle forward or backward with shifter in park.

I tried to relate all this info to mechanic, in detail. I asked him to please not jump to conclusion that trans was toast, even though it might seem so. I could tell he was not really listening to me. I even prefaced our conversation with my usual "I know women aren't supposed to know anything about car repairs, but I'm not a "normal" woman." Oh, yeah, did I mention that part here?

So, he calls me the next day and informs me the trans is toast. $1,700 for rebuild. There is no way to refute or confirm in this type of situation and I knew the possibility existed that the trans was toast. His price was spot on, so I said "go ahead."

Called for status 3 days later. He says "Guess what? Good news, your trans is fine." Surprise, surprise. Have to give the guy credit for honesty, though. He could have done the job and I'd never be the wiser.

He said he pulled the trans and found all was well. Then he put it back, and reinstalled the encoder motor my son had removed. He says that the problem was in the transfer case, and he ended up cooking the encoder motor when it tried to engage on the frozen transfer case?? He replaced the transfer case and encoder motor and all is well with transmission issue now.

Said he traced the 4WD issue down to the TCCM (that he blew me off about when I tried to tell him that). I told him to forget about replacing it. I can do that myself. As long as the car is driving in 2WD right now, I'm good.

So, after this long, involved story, HERE ARE MY QUESTIONS . . . .

I am unclear about the transfer case (I think I am using the right part name - I'm talking about the part the encoder motor attaches to). I thought that was only for the 4WD function. Is it correct that the transfer case was the cause of my not having any drivetrain engagement at all?

I'm picking the car up in the morning. My concern is that what happened to me here is just a symptom of something else. I'm guessing there is a good chance that the car is going to still kick out of overdrive on the freeway drive home and I'm still going to need to replace the TCC, TCM, or PCM to correct the overdrive problem. I said that to the mechanic and he said, "Oh, I see what you are talking about now." Great.

Do I have two separate problems here, or is there a chance these two are connected? Any advice or insight?

I just proofread this, and I sound like a nut-case. :weird: I'm submitting it anyway. I'm at the end of my rope, and everyone here seem to be some pretty smart cookies.

By the way, the repair bill at this point is $1,300 instead of $1,700. Still pretty close to a trans rebuild. STILL THROWING CODE P0894
 
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