Originally Posted by Wirenut
Originally Posted by charge70
Could be a wiring problem from the trans connector to the solenoids or speed sensors.Are you able to rig something up to get codes?


I have wondered that, but wouldn’t it affect it otherwise? Meaning in drive or overdrive it works perfectly.

No I don’t think it’s that smart . It just has a stand alone controller .


I wouldn't trust their computer even though you replaced it once. I get it that changing to a different TCM is an expensive part to throw at the problem. 4L60's have their own inherent weaknesses, but they can be overcome with aftermarket parts including that goofy 3.06 to 1 first gear ratio.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)