Blazer transmission shifts erratically

[7T9Shark]

EVer since I hosed down the engine compartment last week, my '96 Blazer acts real strange, especially when it's not warmed up. When I start out in the morning, the transmission seems to start out in 2nd gear, then quickly shifts into fourth. Sometimes is pulsates between 2nd and fourth when I first start out from a stop, unless I floor it. Then it will delay the upshifts.

It runs fine if I manually shift from 1st, 2nd, 3rd, etc. from a stop. After it gets warmed up, it will alternate between doing this weird shifting and normal upshifting.

My gut tells me it's a controller problem, not an internal trans. issue. The "Service Engine Soon" light has not illuminated so far.

Any ideas?

[viggy58]

what engine? 2wd or 4wd? mileage?

that'll give some of the experts around her some more info to work with and hopefully help you out. sorry but i dont know much about the auto's

[MT-2500]

Need to be put on a transmission/engine capable scanner.
Post back any codes or out of specs data.

[7T9Shark]

I fixed the problem today. (I hope)

All I did was disconnect the battery for a few minutes to allow the ECM to unlearn the bad habit it developed. I ran it, and it is now back to normal. The SES light is now on, but maybe it will go out by itself after sufficient power cycles. If not, I'll take it in to O'Reilly and they can put a scanner on it.

As long as it's running fine, I ain't touching anything.

For those that are interested, it's 4WD.

[MT-2500]

As in upper post.
Obd1 scan will not do the job.
Changed to OBD11 scanner.