TOP DEAD CENTER sensor: The TDC sensor tells the ECU (engine control unit) where top dead center is on the motor.

LOCATION: The TDC is connected to the wiring harness in the engine compartment and is routed between the engine and firewall where it is bolted to the bell housing on the passenger side of the vehicle. To locate find it first on the bell housing then trace up to the under the hood wiring harness. The TDC sensor may be directly wired into the cars computer on some late model Cherokee's.

SYMPTOMS:
1) Car cranks but won't start.
2) Begins to idle rough with all other possible causes eliminated.
Has a tendency to go bad after a hot run, next time you try to start the car it won't kick over. The time of demise is not predictable so be prepared.

REPAIR: Repair is fairly self explained once you locate thge part. Their is several precautions when working on the TDC. Begin by disconnecting the battery, next is extreme precaution when removing bolts from bell housing if the bolts fall in bell housing you may have to remove the transmission. NOTE: Some earlier year models contain extra wiring in the TDC sensor kit. These applications require you to patch additional wiring into the engine control unit.

PRICING: Available at your local dealer
FACTORY LIST PRICING:
1987 JEEP CHEROKEE $33.50
88-90 JEEP CHEROKEE $30.00
91-92 JEEP CHEROKEE $35.00
93-UP JEEP CHEROKEE $48.00

* IT IS RECOMMENDED THAT YOU REPLACE THIS PART BEFORE IT GOES BAD AND KEEP THE REPLACED PART FOR A SPARE. IF THIS PART FAIL IN THE FIELD AND YOU DO NOT HAVE A SPARE YOU WILL NOT BE ABLE TO DRIVE YOUR CHEROKEE.

TDC Sensor Update

If you ever have a no start condition such as is described in the TDC Sensor article, there is one easy way to test for a bad TDC Sensor. This test will yield, nine out of ten times, a startup to get you home. Simply unplug and replug the sensor where it plugs into the main harness near the back of the intake manifold. I know this sounds silly but trust me it usually works and if the jeep fires right up after doing this you can bet that the TDC is the culprit and needs to be replaced. This is the normal easy test for a bad sensor by most of the jeep techs I know including myself.