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/PT 79-0003.pdf
JEA8338 PT 79 0003 Shorted Sensors Cause Many Chrysler Drivability Problems 1996 and later Chrysler Jeep Vehicles No start condition PCM communication failure dashboard gauges inoperative no fuel pump no injector pulse no spark or no Check Engine lamp or bulb check Internal short of any input sensor or sensor wiring to the PCM may cause the above drivability issues Turn the ignition key to the RUN position bulb check mode If the Check Engine lamp illuminates do not run the test below as it is unlikely to be a sensor problem Refer to service manual for other diagnostics With key in the RUN position disconnect one sensor at a time noting if the condition is remedied Begin with the Crankshaft Position Sensor as this has been found to be the most common cause of the problem As you remove a sensor from the system and retry you may notice an audible clicking of the ASD and Fuel Pump Relays This is because they are now energized and working properly It has also been found that the Transmission Transaxle Input Sensors will also cause the above condition Do not overlook any sensor that has an input to the PCM Repair failed sensor or wiring problems and then clear all DTC s Although unlikely there may be an instance where more than one sensor or sensor circuit is faulty To check for this condition all sensors would need to be unplugged If the system activates start reconnecting sensors one at a time until the defective sensor is found Please refer to your vehicle s service manual for specific diagnostic instructions This ProTech bulletin is supplied as technical information only and is not an authorization for repair Problem Cause Solution Note Application Typical Crankshaft Sensor
