Hello,
I bought a 98 blazer a few months ago, with a bad transmission. Would not shift to third, would just skip to neutral. I did a complete rebuild on this thing, finding some very burnt 3-4 clutches, and replaced the input drum as it was flaking off aluminum, I guess from the heat. Also replaced all internal electronics - solenoids, PCM, even the wiring harness. and installed a trans cooler as well.

Re-installed the trans, and connected up a line pressure guage to the test port, after reading about line pressure issues. Sure enough the pressure was really low - 60 psi in P,N,D,3,2,1, and 80 in R. After more reading, found a suggestion to disconnect the big green connector to the trans, and when I did that, pressure was good - 160 psi in P,N,D, and 260 psi in R.

So my question is - does this mean the computer is bad? Or should I try that PCM ground fix? Line pressure does not fluctuate when the wiring is plugged in, just steady and low.

Thanks!

 

A little more info, for what its worth - prior to pulling the connector, had a scanner hooked up to it, and no codes found. After pulling the connector and running thru the gears (on jack stands), it did throw several trans related ones - P0740, P1860, and one other. Then when connector re-connected, and codes erased, no new ones were thrown.