The shift from 1st to 2nd gear in my 4L60E is delayed. Under normal driving it shifts late and shifts hard. Under WOT, it will hit the rev limiter because the shift is delayed. I need to scan for transmission codes. Any suggestions on what to check or where to start?

 

What year car? Mileage?

 

It is a 1994 with 140k miles.

I replaced the shift solenoids and 1-2 shift accumulator. The previous owner had disabled the 1-2 accumulator. They had the piston upside down and washers & nuts in place of the springs.

It improved part throttle shifts but haven't tested WOT shifts.

It's hard telling what has been done to the tranny. I saw Transgo stamped on the separator plate.

 

I forgot to ask if your engine light was on
If you have codes you can access them without a scanner
http://www.obd-codes.com/faq/read-gm...codes-free.php

 

Won't work. He has a 94. Requires a real OBD-1 scanner, or scanning software like (free) Scan9495. The last year that shorting the DLC pins worked was 1993.

Additionally, some of the trans codes don't turn on the SES light.