HELP: ATF oil changed, now stuck in 1st gear
 

Was changing ATF on my daily driver and I think the automatic transmission may be now in limp mode or something. Car is now in 1st gear and won't shift up. At first, the gears were shifting after the ATF change, then when I had to drive the car a little harder to pass someone, the car went and got stuck in 1st. I didn't fully tighten the tranny pan so maybe that caused this? I also changed transmission filter.

This is a 1988 Buick Park Ave w 134k mi.

I disconnected battery for 6 hrs and steped on brake in hope of resetting tranny ecu. Still stuck in 1st. Any ideas??

If it's an '88 there is no tranny ECU. (Even if it were an electronic unit, the engine computer (PCM) controls shifting) It's 100% hydraulic control except for the torque converter clutch (TCC) which is switched on and off by the engine computer. Has no bearing on the situation.

First, make sure the fluid is full.

Sadly it sounds like some gunk broke free and clogged something in the valve body or in the governor or something. It's common for higher mileage automatics to fail shortly after a fluid change.

Took it to a transmission shop. He said there isn't much adjustment.

I was able to get the car out of low gear last night but it got stock again this morning. Appearantly, the transmission will shift up when it's warm. I'll probly trade this car in when I get a new daily driver.

Thanks for the help Peejay!!

Put in a $2 transmission pour in bottle and that put a stop to the shudder and shift issue. Amazing what $2 can do!!

That sounds like you added something other than tranny fluid. Could you tell us what the brand name of this '$2 transmission pour in a bottle' is? Thanks.

It's probably the governor sticking when cold.

It's branded CD-2 or D-2, sold at Pep Boys. It says stop ATF leak and reduces shudder. It swells up some kind of valve. There are other brands but this one seemed credible and was 1/2 the price of others. In future, I would drop in a bottle after ATF change as a good insurance.