Off topic but desperate-- Chevy Trailblazer

2005 Chevy Trailblazer tranny
Daughter just bought a used one and it doesn't always shift from 2 - 3. She can manipulate it by throttle and manual shifting and sometimes it will change. It is an automatic. 130,000 miles 4WD. No idea what model tranny ?

Anyone with experience ? Thanks. Don't want her ripped off by tranny shops if possible.

Check the transmission fluid level, and also the appearance of the fluid. (You have to follow the procedure in the owner's manual to get an accurate level reading.) If it's very low that is likely the issue. If it is almost black in appearance and/or smells burned, that could also be it. Check all of the vacuum hoses that go to the transmission.

4L60E transmission, uses a pair of solenoids controlled by the engine computer to select gears.

3rd gear is selected by both solenoids being off, 2nd gear is "A" solenoid off and "B" on.

I've heard of these solenoids getting sticky after some years, it's possible the "B" solenoid has done this.

Big thanks DustNBone. :thumb: That seems worth a try.

dustNbone said:

4L60E transmission, uses a pair of solenoids controlled by the engine computer to select gears.

3rd gear is selected by both solenoids being off, 2nd gear is "A" solenoid off and "B" on.

I've heard of these solenoids getting sticky after some years, it's possible the "B" solenoid has done this.

Click to expand...

Are the solenoids external to the transmission (on the housing) or internal? Borg-Warner transmissions with O/D used to have an external solenoid to engage the O/D and that would fail, and 4th would fail to engage, sometimes with some warning like the above. If the solenoids are internal, then it could still be bad, gummy ATF causing the problem.

IIRC they are internal, on the input (front) end. You'll need to drop the pan but no further disassembly should be required.

Yep. Drop the pan after disconnecting the shifter cable bracket and they are readily accessible. looks like a 2 hour job.
We gonna try that,anyway.Thanks again guys.

Them SUV's are gas gusslers, but stylish non the less. Should be good to go after the solenoids, if not try a transmission fluid flush and refill. But do check to see what state the old fluid is in, smell it, look at its color and most importantly see if there are any metal bits in the fluid by passing a magnet through the oil. I would buy a plastic fluid pan and a large magnet from Harbor Freight if its in the USA, or whatever you got in Costa Rica. Then if its still not working, then post in the main chevy and suv forums. A last ditch effort, hit up the junk yard and get it check out at the transmission shop.

Yeah I would change the fluid for sure, it's possible the erratic solenoid behavior is a result of metal fragments in the fluid causing their coils to short. ATF is non conductive, but add some metal chunks and not so much. The solenoids should be sealed when new but it's quite possible they're full of semi metallic fluid by now.