Q: Transmission slips if I shut truck off and restart it will do fine for a few seconds then slip again

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Transmission slip once you reach about 30 mph if I stop and restart engine transmission will shift fine until about 30 mph and slip again. Transmission fluid level is fine. Warning light for OD off came up then went back off.

My car has 150000 miles.
My car has an automatic transmission.

A: Th...

Hi there, thanks for writing in.

The reason is starts slipping at 30 is this is where it needs to change to second gear or third gear. The problem is most likely the servo piston for the second gear engagement is binding in the transmission housing due to a worn housing. The fix is to overhaul the transmission and have a sleeve put into the housing during the overhaul with an oversize servo kit. The only other fix would be to replace the transmission with a new or rebuilt unit. The reason it works after turning the car off and back on is because it sets a fault for itself and goes into limp mode, and turning it off will erase that fault until its seen again, at which point it will go into limp mode again. You can have this diagnosis verified by a qualified technician, such as one from YourMechanic, who can then provide you with a suggested repair plan.

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