After a full day, TCC lockup is back!
Did the "click test" in the driveway to see if TCC solenoid worked. Disconnected wires at tranny, put 10A fuse inline with TCC+ (purple) wire, and grounded TCC- (tan/blk). Blew 10A fuse. Looked at wiring diagram, showed 15A fuse, so swapped, and then the click test worked; solenoid then pulled in with only about 450mA. Must have been stuck (?). Anyway, rigged up switch and was able to lockup while moving. RPM drop obvious when doing 50 and throwing the switch.

But of course the computer is still not happy. Shifting now seems back to normal, but still getting (old) 26 quad-driver code, and new 63 & 65 codes for egr. This is with both computers...I've now left the original computer installed and the ebay unit is now in the trunk.

Checked out other parts of quad driver: Fans run. TCC works (can see it work with a meter hooked up). Checked canister solenoid (disconnected it and it works with 12V applied). EGR disassembled/cleaned again and each of the 3 solenoids work with 12V applied). A/C is off.

Checked TPS, no dead spots.

Guess now I need to buy the scan tool to see what its problem is now...hopefully it will tell me what the computer thinks it really wrong.

Not sure where the end of the story lies, but thanks to all for help so far.

You wan't to check the TPS voltage at idle position. Key on car off.
Signal wire should read 4.2-4.6 volts on a C motor.

WELL..........

This right here...it'* pretty frustrating. :?
TCC lockup worked with the switch. I threw the switch at 50 mph and the rpm dropped a by a few hundred. But on the road, when hooked back up to computer control, I initially thought (wished?) it was working, but now that I've driven it for 2 days, it is obvious that TCC still does not lock. I put a meter on the supply side of the solenoid and when going above 48 with constant throttle, voltage is applied. But set cruise at 70, it turns about 3200 rpm. Maybe it'* slipping. Beats me. Thinking it'* time to get a 'real' FSM, and a code reader. And be ready to dig deeper.

Checked TPS voltage: 0.4V at idle, 4.2V WOT.

Not sure why the code 63 and 65 now come up. I did disconnect the TPS and MAP, but plugged them back in before running again. Took off EGR and verified the 3 solenoids worked, too. This is a distraction, but it should probably be taken care of before more transmission wars...

Too bad it'* out of warranty (but only by a decade or so)...

It should see a constant twelve volts (from the brake switch) and the ground is switched on and off by the ECM. Are you using a VOM between hot and ground to get the indication? On my car there are two brake switches on the pedal arm. Is one out of adjustment? Again, this is a '90 FSM, but I just looked at a GN transmission this last weekend and the solenoid is essentially the same.

Using Fluke DVM. Haynes schematic says Pink/black is 12V when running.
Unplug wires from brake switch, 12V is there. Plug wire back into switch, drops to 9.4V.
Push brake pedal, switch opens, 9.4V goes to 0 (as expected). "12V" wire is also 9.4V when brake not applied, but goes to 12V when the brake pedal is pushed (switch is open). Haynes manual would have you believe that the feed to the tranny is directly off the brake switch...it acts like the computer actually controls it for the following reason: I watch the voltage rolling down the blacktop, and it is 9.4V sometimes, but usually 0V. It drops from 9.4V to 0V with the brake (duh) or with even the slightest amount of gas pedal. Even at 70mph on flat road, the voltage is 0, unless you take your foot off the gas completely.

Measured resistance of TCC coil (wires unplugged) and got only 0.7 ohms, same with probes reversed. This tells me about 13A, but the meter only reads 450mA. SO, maybe computer can only source 450mA, and it would explain why my 10A fuse blew. Any idea what the TCC coil resistance ought to be??? I'm thinking maybe 10-20 ohms, but mine is not close...

Next test is to verify once and for all whether or not the ground is pulling in from the computer. I'll attach an LED to the control line (that'* pulled up to 12V) and if the computer grounds the line, then the LED will turn on. Project for another night...

For the life of me I cannot find a resistance value listed in the FSM. The manual says battery voltage should be present at the hot line to the TCC. The switched ground in the ECM is quad driver #3. The power wire from the brake switch is also tied to the ECM, although the path is not through the ECM. It does make a definite mention that the TCC circuit cannot be tested with a high impedance or digital ohm meter, it says use a scale type ohmmeter? Low voltage indicates a fault in the solenoid, or a wiring connection and checking at splices is mentioned. There are also capacitors in the brake switch circuit but I do not know about how that may affect a reading? The wiring to the solenoid looks pretty stout, but a calculated 13 amp draw on a 15 amp circuit sounds pretty high, especially considering other items controlled by the quad drivers is powered from the same circuit. I will ask my friend to see what sort of reading he gets across the coil for his TCC. I cannot get at mine easily as the turbo piping is in the way. One other thing I found is apparently pin "F" in the ALDL is connected to the ground side of the TCC.

I found the coil resistance in the manual. It is supposed to be 20 ohms or greater and made no mention of a special ohmmeter to read it. It sounds like it is partially shorted internally dragging the voltage down.

Yup, 20 ohms or more...kinda points in that direction, don't it. Thanks for all your help.

Before I saw your reply, I tried the LED test, and it did not work out as I had hoped. My reasoning was that the LED would be off until the ECM grounded the line, but that was not the case. SO there may be more than one thing wrong with it...obviously the solenoid is not right. But the solenoid failing may have blown the driver circuit in both ECMs.

I plan on picking up a real FSM now, since my Haynes manual does not address R&R of the solenoid. I'm not sure the Haynes schematic is 100% accurate either. I think I found the solenoid on Rock Auto and it seems fairly cheap at about $23. But then they list a 'delay harness' at $41. Wonder what that is???

And of course that brings up another question: Can the ECM be put in a 'test mode' maybe with a scan tool, to toggle the quad drivers one at a time to see if they are blown or not? A simple resistive load pulled up to 12V would work if there was a way to turn them on and off...


Looks like I'm in for some more fun.

I suspect the "delay harness" is the same thing I used for years. It was a short harness with the correct mating connectors to install between the stock harness and the transaxle plug. The purpose was to not allow lockup of the converter in anything but fourth gear. I took it apart and it has what appears to be a transistor and a resistor in the harness. I'm no electronics wizz, but I assume the transistor acted like a relay. The system works very well.