My automatic transmission on my 1982 is slipping. It seems to be most prevalent from 1st to 2nd gear. Usually soon afterwards it goes into 3rd and stays, which is the limp mode. HERE IS THE INTERESTING THING I FOUND: while I am rolling in neutral after falling into limp mode/3rd gear, if I turn the ignition off for 1 sec and then back on, and then place it in Drive, I hear engagement of a lower gear (I have felt 1st and 2nd engage), and it drives fine for a little while until it’s time to upshift.
It is like the computer gets reset, but I have never heard of such. I want to think that the computer does not know the engine speed, and gets confused but is somehow temporarily fixed by ignition on/off. It does not work simply because RPM is down or that I am in neutral. BTW, this only works for a few shifts, then back to limp.
So far I have:
1. Checked for proper fluid level and it is exactly correct
2. Read 14 v at fuse 13 on the transmission side and watched it as the system slips. It remains present, goes off when I turn the ignition off, and then is back on when ignition is on and the downshift occurs
3. Checked the throttle cable. When at idle the rheostat is fully where it should be, at ½ throttle it is ½ way through its course, and at full throttle is fully turned.
4. Connections to the computer and transmission are very nice and tight. NOTE: this is a new DMC “advanced” auto trans computer installed by DMCFL about a year ago, so while I suspect the computer or a solenoid, I am looking elsewhere first.
5. Disconnected the full throttle microswitch for now so that is out of the equation.
I have found less information on the wiring for the auto trans compared to manual car, and in fact my big wiring diagram does not even show a fuse #13. I have seen the treads that show the board and some other components, but I could n=have missed something of course.
So here are a few questions:
What is the wire up at the firewall engine connector harness that provides the +12 v and ground for the computer? Looks like there is one 6 wire and one 3 wire L-shaped connector up there. I could check that to be sure it is getting what it needs. Or even jump it to a known good voltage source to eliminate that issue.
I read that manifold vacuum also helps to teach the computer the engine speed/load. Where is that connection? I would like to check it.
I can check the logic voltages as well, but I was planning on doing that later. I will also check the filter (messy job, so I am saving that too, after I check what I can that is easier to access).
Any suggestions? Has anyone experienced the “reset thing”.
steve