Long time reader, first time help requester. I have a 1998 Firebird Base Model (3.8 L V6 / 4L60E Auto). The engine was trashed when I bought the car, so I replaced with a crate engine and rebuilt the transmission while everything was out of the car. I also installed a Transgo SK 4L60E shift kit as well. When the car has been sitting overnight or long enough to cool down, it won't downshift into 1st gear at a stop, and it won't upshift into overdrive. Pulling the shifter into 1st gear when stopped has no effect. The car still starts out from a stop in 2nd gear, and it shifts up into 3rd gear fine. If the car is shut down after driving for a mile or less then restarted, it shifts fine. I changed the 1-2 shift actuator with no effect on the issue. It seems like an electrical problem to me, but am unsure where to start troubleshooting. The 2nd Button in the console is not lit up, but seems to work when it's pressed. Could it be that that circuit is not releasing? How would I test that circuit? Thanks everybody for your help.

 

it sounds like it is going into limp mode...could be faulty solenoids in the valvebody

do you have a scanner to check for codes?

 

thunderstruck thinks your trans might be in "limp mode" which is 3rd gear and often confused with starting in 2nd gear.
However, if you are SURE it is shifting from 2nd to 3rd, then it is not limp mode.
If shift solenoid A does not turn on, then you will only have 2nd and 3rd gear. That could be caused by a burnt out solenoid, wiring problem to the solenoid, or a clogged/stuck solenoid.
The burnt-out/wiring-problem will usually give a MIL light and then put you in limp mode.
If you decide to replace the solenoid, you might as well replace both as they are only $12 each and it will likely take you an hour. You also won't mix up shift solenoids A and B that way.

 

assuming it actually automatically does the 2-3 shift I would have to say solenoid A is stuck or the valve , If this shift only occurs manually I would have to say limp mode either way scan first.

 

Thanks for all the tips. Had the engine codes downloaded...turns out the 3-2 downshift solenoid was bad. Changed it out, and now the shifts are nice and crisp.