The 1999 Jeep Grand Cherokee features a crankshaft position sensor, or "CKP," which monitors the speed at which the engine's crankshaft rotates and relays that information to the engine's various electronically-controlled systems. The sensor is particularly sensitive to heat, which can cause the sensor to burn out. Fortunately, replacing the Cherokee's CKP takes only a few minutes and does not require disassembly of the engine.
Back the vehicle's rear wheels onto a pair of lift ramps. Raising the vehicle is necessary to access the crankshaft position sensor, which is located at the top of the transmission's bell housing, just behind the oil filter.
Disconnect the CKP's electrical connection plug. A large black wiring loom protrudes from the back of the CKP. At the end of the wiring loom is a plastic clip, which attaches to the engine's wiring loom. A single tab located on one side of the clip secures the CKP's wiring loom to the engine's wiring loom. Pull the tab away from the clip until the tab disconnects, then pull the CKP's wiring loom away from the engine's wiring loom.
Remove the crankshaft position sensor. The sensor is held in place with a small metal bracket. A single bolt is inserted through this bracket and into the bell housing to hold the sensor in place. Remove the bolt with a 11 mm wrench, then withdraw the sensor from the bell housing.
Slide the replacement CKP sensor into the bell housing, then install the 11 mm bolt through the bracket on the side of the sensor with a wrench.
Press the tip of the CKP's wiring loom into the fastener at the end of the engine's wiring loom until the two loom connectors click together.
Drive the Jeep off of the lift ramps.
