Engine Electrical Parts Jeep Grand Cherokee WJ
Ignition Coils, Sensors & Alternators for Reliable Starts and Smooth Running (1999–2004)
When Your WJ Misfires or Won't Start, a Sensor Is Usually Behind It
Under the hood of the Grand Cherokee WJ, the classic distributor ignition is gone. The 4.0L inline six fires through an ignition coil rail, the 4.7L V8 through individual coils sitting directly on the plugs, and the 2.7L CRD diesel is fully electronically managed as well. The engine computer relies on signals from the crankshaft and camshaft position sensors, the throttle position, pressure and temperature sensors and the oxygen sensors. After more than twenty years of heat in a tightly packed engine bay, plastic housings turn brittle, connectors corrode and windings wear out. Typical symptoms are misfires, a rough idle, higher fuel consumption or an engine that won't restart when hot, usually together with the check engine light. Many sensors drift and deliver false readings long before they fail completely. That is why replacing them in time pays off: it protects the catalytic converter and the engine from consequential damage.
From the Ignition Coil to the Transmission Sensor
- Ignition & glow system: Ignition coils for the 4.7L V8 and the coil rail for the 4.0L, plus spark plug sets for the six-cylinder, glow plugs for the 2.7 CRD and the ignition capacitor.
- Starting & charging: Starters for the 4.0L, a starter for the 4.7L and 136 amp alternators, along with the ignition lock cylinder, ignition switch, re-keying tool and key blanks with or without transponder.
- Crankshaft & camshaft: Crankshaft position sensors for gasoline engines and the CRD diesel, camshaft position sensors for the 4.7L, the oil pump drive with integrated cam sensor for the 4.0L and the V8 knock sensor.
- Fuel mixture & emissions: Throttle position sensors for the 4.7L, idle air control motors, MAP and intake air temperature sensors and oxygen sensors before and after the catalytic converter, plus the leak detection pump (LDP) of the evaporative system.
- Temperature, oil pressure & cooling fan: Coolant temperature sending units, oil pressure sensors with one- or three-pin connectors, the ambient temperature sensor and electric radiator fans including the fan relay.
- Automatic transmission electrics: Neutral safety switches and neutral/reverse switches with a wiring repair kit for the 42RE/44RE, the transmission pressure sensor, speed sensors and the torque converter pressure sensor for the 45RFE.
Standard Ignition for the Sensors, Crown for Starters and O2 Sensors
Just over half of the range comes from Standard Ignition: ignition coils, the ignition switch and almost all of the sensors. Crown Automotive supplies starters, alternators, oxygen sensors and keys, Champion the spark plugs and Dorman the leak detection pump, oil pump drive and radiator fan. All four are US brands. Ridex and NTY add European alternatives for sensors, glow plugs and the fan, while Alanko from Germany builds the starter for the 4.7L.
Which Sensor Fits Your WJ Engine? We'll Check Before You Order
On the WJ, many sensors differ by engine and model year; on the 4.7L, for example, between the 1999–2000 and 2001–2004 model years. Send us your VIN or the OE number of the old part and we'll confirm the fit before you order. We're also happy to advise on mounting position, connector type or tightening torques for sensors and spark plugs. Your order ships from stock in Germany as fast as possible.