Why won't the automatic transmission in a 1991 Buick Lesabre shift out of first until 35 mph not shift into third?

Answer 1

First make sure the fluid is at the correct level, check "hot, idling, in park". Not too much or too little. Put the correct kind of fluid in if you have to add. If there is too much in it, you can maybe suction it out of the dipstick tube, Jiffy lube could do this. If the fluid is at the correct level, check the fluid on the dipstick for grit or debris or shiny metal. If so, the transmission may need overhaul. In general, it sounds like it refuses to upshift both times it has to do that, possibly would shift into 3rd if you got up to 90 mph? Backing off the throttle doesn't speed the upshift up? Could mean fluid passages are restricted or valves are sticking. About all you can do is put the right type and amount of fluid in it. But transmission work isn't as scary as it sounds, though it may be expensive. But once you get the diagnosis shop it around. Just take it to a reputable place. Have someone look at it. If it seizes up on you while you're driving, your car will never have stopped so fast and you may have an accident. also check you vacume modulator valve it may be going bad or it might just need a trans service and a new filter