After about 10 minutes of driving transmission shifts down to 3rd gear. After car cools to ambient temperature 4th gear ok for about 10 minutes.Could this be a transmission temperature sensor? Could this be a ground wire problem? Where is the ground location for that circuit?1987 Allante

 

CODES PLEASE !!!!!
any of these?

E039 VCC Engagement Problem VCC
E057 Shorted Fourth Gear Switch circuit or Open 3‑4 / Shift solenoid VCC


here are a few possibilities ...

1. the shifting solenoid is on its last leg,

2. the fluid is low - this 440 turbo hydro transmission is extremely sensitive to low fluid. this may also show up as infrequent downshifting and up-shifting at highway speeds. If the dip-stick is not original, it may also be giving you a wrong low level. FILL it to the MAX on the dip-stick .. but .. do not NOT overfill.

3. the fluid needs to be changed out, build up sludge and glazing of clutches -

Recommend you add a bottle of LUCAS transmission FIX, drive it for 100 to 300 miles or so, then do a transmission service (fluid, gasket, etc. change) AND add a bottle of LUCAS (yes, again). i believe this stuff, to an extent, removes sludge and glazes.

My '88 went through downshifting and up-shifting, refused to go faster than 85mph, almost parted it out, even bought a solenoid from a parted car.
Then i found out the dip-stick was a replacement that called for ONE quart less than needed. Added the "extra" quart and problem become history.

however probably because of the downshifting and up-shifting, trani was now slipping, so i added LUCAS and the car's issues went away, having no issues and easily hitting 100 mph. drove it for a week, changed the fluid including another bottle of lucas .. she runs like new.

sold the solenoid ...



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