Originally Posted by HeyYou

Have you removed the check valve in the trans cooler line yet?

Usually, the trans temp light should come on before the PCM dumps you out of O/D, and turns on the light. (at least, I think it works that way on the 96-97 trucks...)

Do you get any codes?

Originally Posted by Wayiam7200

I have 1 code but don't think it's related? P1391 and no I haven't taken off the check valve

Originally Posted by HeyYou

I am not even sure my truck even HAS that particular light. I have never seen it at least..... not sure where it should be.

PCM will disable O/D on it's own if it sees trans temp getting to high. I suspect that is what is happening to you.

Check valve will be at the end of the steel line coming from the trans, going to the radiator. Right near the frame rail at the front, passenger side of the engine. That lines goes to the lower fitting on the radiator. There are a couple threads about eliminating it in the DIY section, with pics of what it looks like. Reason I ask is: the check valve is notorious for gumming up, and restricting flow thru the cooler. So, trans overheats, PCM disables O/D..... (which is why I asked about the trans temp lite. It *should* come on shortly before the truck drops out of O/D.....)

Might be a plugged up check valve, might be a flaky temp sensor, or, might just be a bad connection at the PCM.... Probably wouldn't hurt to pull the connectors there, and give 'em a good cleaning.

Originally Posted by zildjian3707

decided just to take it in cause it blew 3 codes at once and i had had it with it. well they looked at it for idk a few minutes after i left and discovered it will 2 and some change quarts low on tranny fluid...hmm ya that might **** it off. so im gonna check for leaks this week. im mad i didnt check that haha. well my mechanic only charged me for the quarts and nothing else. for now its working fine now, will see how it goes.