1990 torque converter lockup issue

[Ecomike]

Yes that is that right part location for the TPS. It has two separate connectors, one flat, one square. Each has a 5 volt input wire, a ground wire, and TPS output/return. The square one (four pin holes, 3 wires) is for the TCU, it goes from, .2 volts to about 4 volts, from idle to WOT, IIRC. The ECU side is a flat 3 pin connector, 3 wires that is connected the ECU, engine computer. It is .83 volts at idle, and about 4.3 volts at WOT (IIRC). Also be sure to test the ground wire on each (should be less than 1 ohm). Both of mine were terrible, I had to run new ground wires from both sides directly to the battery (-) post on mine.

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[lawsoncl]

I think for the dual output TPS, the square connector had the voltage running backwards from normal. That is around 5v at closed throttle and towards zero at wot. More than likely the TPS is bad.

 

[Cox89XJ]

When I installed a M/C and booster out of a 99XJ in my 89XJ. I discovered the little limit switch on the brake pedal. If it's not made up with the brake pedal not depressed, the torque converter won't lock up.

 

[Ecomike]

I think for the dual output TPS, the square connector had the voltage running backwards from normal. That is around 5v at closed throttle and towards zero at wot. More than likely the TPS is bad.

That is correct, the ECU side of the TPS is high voltage at idle, the TCU side is low voltage at idle on the signal return wire. They should both have a good solid 5 volts feed wire, and a good ground wire with less than 1 ohm resistance to ground at the battery negative terminal. I always test the 5 volt and ground with the sensor disconnected and power on, then I test the return signal voltage at idle and WOT with the engine off, power on, and the sensor connected.