Tps???

1988 XJ 4.0 AW4:

I did a search.... went by the book and the suggestions on this site for testing and adjusting the TPS. I have never tested this on a jeep... so either I am doing it right and the TPS is bad or I am doing it wrong...

I used the flat plug and with the ignition key on (not running) and using B as ground and A as supply and C as return..... A measured at 4.86 volts and C was at 0.94 volts with throttle closed and 4.54 volts with throttle open.

I then tried using the square plug with the same procedure and had zero luck.

The book says use the center wire for positive and the black wire for ground and it should read more then 200mv throttle closed and less then 4.8v.

Now that I am confussed... what the hell am I doing wrong?

The adjustment procedure for pre-HO TPS (ie up to 1990) is different for automatic vs manual transmission. For the AW4 automatic:
THE FOLLOWING ADJUSTMENT PROCEDURES REQUIRE THE USE OF A VOLTMETER WITH A SENSITIVITY OF AT LEAST 20,000 OHMS/VOLT.

TPS Adjustment Procedure - 4.0L engine with AUTOMATIC Transmission
NOTE: THE TPS FOR THE FUEL INJECTION SYSTEM IS INTEGRAL WITH THE TPS FOR THE
AUTOMATIC TRANSMISSION. THEREFORE, ADJUSTING THE TPS CORRECTLY FOR THE TRANSMISSION WILL AUTOMATICALLY ADJUST THE "FUEL INJECTION" TPS PROPERLY. THE PREFERRED METHOD FOR ADJUSTING THE TRANSMISSION TPS IS USING THE MS 1700 TESTER IN THE "AUTO TRANS TEST" MODE AND FOLLOWING THE INSTRUCTIONS THAT THE TESTER DISPLAYS. HOWEVER, THE TPS CAN ALSO BE ADJUSTED USING A VOLTMETER AND THE FOLLOWING PROCEDURE.
1. Turn the ignition switch to the "ON" position.
2. There are two wire harness connectors attached to the TPS. Input/output voltage is checked at the SQUARE, FOUR-T ERMINAL connector. The terminals are identified by the letters A, B, C, and D molded into the connector.
3. Do not unplug the connector. The voltmeter leads must be inserted through the back of the connector to make contact with the terminals. Connect the positive lead to terminal A and the negative lead to terminal D.
4. With the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.
5. Remove the voltmeter positive lead from terminal A and connect it to terminal B. The "output" voltage should be 4.2 volts (82% of input voltage). If this is not the case, continue with this procedure.
6. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 4.2 volts with the throttle closed. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws.
Adjustment is now complete.

I've used this procedure (posted here a while back, lifted from a factory service manual). Aim for output voltage of 82% (without opening the throttle). The dealer uses a diagnostic computer to set it (IF they have the setup for the Renix ignition), and can do a better job than the multimeter method.

Ok here is my data for the TPS:

D=.9vdc

I went ahead and added a second ground to this wire. Now it reads 0vdc.

A=4.66vdc
C=3.63vdc

I then adjusted the TPS to read 3.90vdc and check it all over again.

I also checked some other sensors. For those that have already seen the issues I was having in the other thread... I will post it all there.