Need help repairing TC lockup

[gavio]

Hi All:

I had a rebuilt 700r4 installed in my 83 6.2 G-van this winter, and since then, the TC has not locked up. The tranny works fine and feels solid otherwise. The wiring going to the TC is working properly according to the manual - it's the kind with one wire, 12v above certain RPM and interrupted when brakes applied.

Manual says issue is inside tranny - I dread going in there alone - but funds are short.

I'm wondering, though..... the guy who sold me the trans rebuilds only later model trannys for use in all applications, so is it possible that the problem is because the internal wiring is set up for later style operation with multiple wires connecting to it?

If so, can it be resolved without busting into the tranny?

I'm OK with making it manual lockup, though I'd prefer to have it work the way it should.

If I have to take the pan off, is the fix likely to be easy (just replace switch, maybe) or is it complex, like I really ought to just fork over the dough to have it done?

The tranny came from a shop out of state, and the guy started to help me troubleshoot it, but then he disappeared and seems to be gone from business - he'd been in business a long time, so I don't suspect intentional misdeeds on his part, but nevertheless, he's gone.

I had it put in by a local shop, and they seemed OK, but I don't know that they've really got the know-how for inside tranny stuff.

Any help and insight appreciated. I've searched the forums, learned a lot, but just enough to stay rather confused about how to address this particular situation.

Thanks

Gavio

[john8662]

I'd verify that you're indeed sending voltage down to the transmission, to give you a lockup.

This can be accomplished with a test light, in a van, just remove the dog house, connect your test light to a 12v source, you may have to rig a wire to fit inside the connector to the trans (you'll just disconnect the plug from the trans for testing). Run the engine like you'd expect to get a lockup, see if the light comes on, if not, wiring issue, could be brake switch, or the TPS (also the adjustement of the TPS).

If you get a light at proper times, then it's something internal to the transmission for sure.

You could pull the pan and check the wiring, make sure one of the connectors to one of the switches didn't come off, there can be a few (i think up to three), usually just one or two. You can also check out the switch, test light works here too, just apply voltage.

Besides that, it's wiring for the switches on the valve body, or a bad solenoid (possible) for the TCC.

J

[gavio]

Thanks, John, the wiring is indeed working correctly, with one wire supplying 12v above certain rpm and interrupted when brakes applied.

I guess I'm still wondering if it's for sure screwed up inside, or is it a wiring mismatch with the newer style tranny, which could perhaps be resolved without going inside.....

I can't tell you how much I DON'T want to drop the pan, for a variety of reasons.

[nlines]

What about the throttle to transmission cable adjustment?

[gavio]

TV cable is adjusted correctly, tranny upshifts and downshifts as it should. Just doesn't lock the TC.