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Jeep Cherokee TPS Replacement

Q. Vincent, I have a 1987 Jeep Cherokee Laredo straight 6 with a 5-speed manual transmission. I am the original owner of the vehicle. It has 102,000 original miles on it. The car has had its TPS sensor replaced once in 1993 because of high idle. My problem with it, now, is similar (worse) to what was occurring in 1993. When I start the car, it revs up and the idle does not come back down to normal operation.

Jeep Cherokee TPS Replacement

I have tried letting it "rest" and trying several more times to start with the same results. The only way, at this point, that I can get the idle down is to open the hood and tap on the IAC sensor. This sensor was replaced just two months ago by my husband. Now, we are wondering if we replaced a good part and our problem is actually the TPS unit.

I went online to see if there was any recall on the TPS and found that there is a service bulletin outlining my very problem, but no recall. I contacted the local dealership and was told that the part had to be ordered at a cost of $145.00 and that it should be in installed by a technician because it has to be set by computer codes.

We are now on a fixed income and I was hoping to hold onto the car for another year, I had hoped that my husband could replace the sensor, saving us a labor charge. Based on what I've told you, do you think it wise to replace the TPS rather than the IAC unit? The car has been faithfully maintained (oil changes, tune-ups, etc.) and has been taken to a mechanic whenever something serious needed to be done.

Is it possible that the TPS unit could be bad after 10 years and that this is not a sign of something more that I should be looking for? Two mechanics have told us that Jeep is notorious for having TPS issues and that this is a "design flaw" in the motors. Any help or suggestion you can provide will be greatly appreciated.


A. Before I go swapping parts I would recommend cleaning the throttle chamber and ISCV. Many times this is enough to solve the problem you describe.

Since I haven't looked at the car personally, I can't tell you for sure if a new TPS will fix it. With the history of this vehicle and their TPS's the best I can say is that it is a good possibility it will fix it.

If you do go for the TPS, here is the adjustment procedure from the aforementioned TSB:

TPS Adjustment Procedure - 4.0 Liter Engine With Manual Transmission

  1. Turn the ignition switch to the "ON" position.
  2. Do not remove the electrical connector from the TPS. Connect the positive lead of the voltmeter to terminal A and the negative lead to terminal B of the TPS connector (Figure 1). The leads must be inserted through the back of the connector to make contact with the terminals. The terminal identification letters are molded into the connector.
  3. with the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.
  4. Remove the voltmeter positive lead from terminal A and connect it to terminal C. The "output" voltage should be 0.8 volt (16% of input voltage). If this is not the case, continue with this procedure.
  5. 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 0.8 volt 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.

Jeep Cherokee TPS Replacement

Additional Information provided courtesy of ALLDATA

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