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Jeep Cherokee High Idle And Clicking

Q. Hi Vince: I have a couple of questions about my car:

  • 1988 Jeep Cherokee Chief 4WD
  • 4.0 liter L6 engine
  • Manual transmission
  • 213,000 miles
  • Fuel Injection
  • P/S, A/C

Jeep Cherokee High Idle And Clicking

I hear a clicking noise whenever the car is moving, proportional to speed, coming from the right-front wheel area. My son took the car into his auto-shop class at school and they told him the universal joint in the front axle was bad.

This would be the universal joint thats directly behind the right front wheel brake assembly and apparently part of the front axle. My question: is there any way to confirm this diagnosis, and if so, whats the best way to remove and replace that universal joint?

The car idles fast, usually around 1,500 rpm. suspect the idle speed stepper motor and\or throttle position sensor, but I dont know how to determine if either or both is bad. What do you suggest?


A. There was a TSB, 02-54-88 dated September 26, 1988 that might apply here. You can get a copy from your Jeep Dealer.

A close visual examination may reveal a bad joint. Usually you will see rust and torn rubber grease retainers. If you grab the axle shaft and move it up and down, left and right you may feel play in the U-joint. Spinning the shaft and listening for noise is another way to determine a bad U-joint.

To replace it, you will need to remove the axle shaft from the vehicle. I wrote an article, DIY: Universal Joints that will take you through the replacement process step by step.

The high idle could be caused by a bad MAP sensor. Here is how to check it.

  1. Before starting the test, check the condition of the electrical and vacuum hose connections. Repair if needed.
  2. Turn the ignition switch ON (the engine should remain off), and test the voltage from connector terminal B to ground with a voltmeter. Voltage should be between 4 to 5 volts. With the engine started, warmed to normal operating temperature, and idling, the voltage output should drop to 1.5 to 2.1 volts.
  3. Check for voltage at ECU electrical terminal C-6 in the same way as in step 1. The voltage readings should be the same as in step 1. If the voltages are different, then the wiring harness should be suspected as the problem area.
  4. Check the supply voltage to the sensor by connecting a voltmeter to connector terminal C and a ground. Voltage reading should be 5 +/- 0.5 volts with the ignition switch ON. There should also be 5 +/- 0.5 volts at ECU electrical terminal C-14. Repair wiring harness if necessary.
  5. Check the sensor ground circuit between electrical terminal A on the sensor and ECU connector terminal D-3. Connect one lead of an ohmmeter to electrical terminal A of the sensor and the other to ECU connector terminal D-3. The ohmmeter should indicate continuity. Repair wiring harness if necessary.
  6. Check the sensor ground circuit at the ECU electrical connector. Connect an ohmmeter between terminals D-3 and B-11 of the ECU electrical connector. If the ohmmeter does not indicate continuity, check the sensor ground connection at the right side of the engine block at the oil dipstick mounting stud. If the ground connection is good, replace the ECU.
Jeep Cherokee High Idle And Clicking
Jeep Cherokee High Idle And Clicking

Another possibility is the Throttle Position Sensor (TPS). First disconnect the TPS and, with a voltmeter, check voltage at pin A (5.0 volt supply) and B (ground). There should be 5.0 volts. If not, there is a wiring problem between the TPS and PCM.

Reconnect the TPS connector and check voltage at pin C (+) and B (ground). There should be approximately 0.8 volts. If there is the TPS and wiring is good. If not, replace and adjust the TPS>

You need a special "exerciser tool (P/N Ele. Ct.01)" to check the Idle Speed Stepper Motor. However, I think the problem is most likely being caused by a bad Coolant Temperature Sensor (CTS).

Additional Information provided courtesy of AllDATA

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© 2005 Vincent T. Ciulla

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