2005 trailblazer 4x4 4.2 shift solenoid problem

[Doug Fresh]

Any ideas on why my trailblazer seems like it's stuck in 3rd gear, there's like no power taking off but when you get speed it gains power back, autozone said it was shift solenoid B so we replaced it and put new fluid and filter in it, didn't fix the problem. Could it be the other shift solenoid A? Or the 3-2 downshift solenoid? It's transmission related because the engine has power. Any ideas

 

[Mooseman]

Was it throwing a code pointing to the shift solenoid?

Do you feel it shifting through the gears? Maybe it's just a lack of power because of a plugged cat?

 

[Doug Fresh]

Autozone said replace B/ 2-3 shift solenoid i forgot what code that was. It has all the power in reverse and you get a little more power if you run it through the gears manually, I guess I really never paid attention if it shifted gears in Drive but it just seems like your starting off in a high gear, like there's no power. You could push the pedal to the floor and slowly accelerate until you gain some speed then you get some power back, its weird to because as soon as this started happening the key won't come out of the ignition now either

 

[Reprise]

Hmm. I'd replace the ignition switch first; the fact that those two things happened together is probably *not* a coincidence, and the switches have a habit of failing (without warning; many here carry a spare with them so that they can swap it in when needed.)

As it turns out, the A & B solenoids are interchangeable. While it might be messy to drain the fluid again (if you don't have a drain plug), it would cost you nothing to swap them, and see if the problem follows. It's possible that *both* solenoids could have gone south, but that's pretty rare. As you know by now, the A / B solenoids aren't terribly expensive; you could just throw a new one in the other position and save yourself a pan drain (or, swap them, and if that *doesn't* resolve / change the issue, take the new one back w/o installing it))

What's likely, since you're starting out in 3rd currently, is that you're in failsafe / limp-home mode (b/c 3rd gear is the only forward gear that doesn't require electrical power). Check the wiring harness for an open / short; if you find one, replace the harness (the wires terminate into a round plug on the outside of the case on the passenger side, and it can be difficult to get that plug out / in, with the trans in the default location (e.g.; you might have to loosen the rear mount, bend the shield on the passenger side of the case, or drop the trans outright to get to the plug))

Since you can (apparently) shift manually, the problem is most likely electrical in nature (which again, implicates the ignition switch, if you think about it). Use 2 or 1 to start out with until you find the cause & get it fixed. (doesn't matter; you'll be in 2nd by default, and you don't have 1st right now)

Here's a pretty good comprehensive guide to common 4L60e issues & fixes. This page states at the top re: fuses & to check them first. That's the cheapest / easiest solution of all, of course. May / may not apply (this is on a an F-body section of LS1Tech, although it was lifted from a GMT400 site, which is the 88-98 full size pickup (C/K series).

 

[Doug Fresh]

Yeah that's what I was thinking too, I'm thinking I'll start with the ignition switch and go from there before I start messing around with those solenoids again. And if that don't fix it I'll check the wiring. Thanks for the help!