Jeep Cherokee XJ crankshaft position sensor: symptoms, tests, part numbers

• Cranks but will not start. The computer only grounds the auto shutdown (ASD) relay, which powers the injectors and ignition coil, when it sees crank and cam sensor signals. No crank signal, no fuel and no spark.^[13][15][18] Unverified The factory manual adds that it shuts the relay off after about 3 seconds of cranking with no signal. (factory manual only)^[15]
• Code P0320 or P1391 (1996–2001). P0320 means no crank reference signal while cranking; P1391 means the crank or cam signal is dropping out intermittently.^[15][22][23]
• Unverified Stalls or won’t restart when hot, fine when cool. Sensors are reported to test fine cold and fail hot. (enthusiast consensus, not a factory statement) ^[3]
• Unverified Tachometer drops to zero while cranking or just before a stall. (needs a source before publishing)
• 1987–90 Renix: Unverified service bulletin 18-51-88 gives “No start, cranks okay” as the symptom of a weak signal. (factory bulletin only)^[1]

From 1991 the sensor is a Hall-effect unit. It reads three groups of four notches in the 4.0L flywheel or drive plate, and the computer uses them for engine speed and crank position.^{[13][15][16][22]} It’s a three-wire sensor: a supply from the computer, a ground and a signal back.^{[13][20][15][17]}

Unplug the sensor and test at the harness side with a digital multimeter, key on and engine off. A full factory test of the sensor itself needs the DRB scan tool and the separate powertrain diagnostic manual, so what follows checks that the sensor is getting what it needs.^[13][14]

1997–2001 (5 V supply)

Factory wiring diagrams and the 2001 service data agree on these.^[15][20][17]

1. Orange (K7) to a good ground: about 5 V. The 2001 data gives 4.5–5.0 V.^[17][20][21] No voltage points to the wiring or the computer, not the sensor.
2. Unverified Gray/black (K24) to ground: 4.5–5.0 V. (2001 service data only) ^[17]
3. Unverified Brown/yellow (K167) to ground: under 5 Ω. (non-factory sources only) ^[17][16]
4. If supply, signal and ground are all good and the truck still has no spark or injector pulse, or code P0320 keeps setting, suspect the sensor. Unverified The 2001 data also lists the cam sensor, the flywheel or drive plate, the wiring and the computer as possible causes. (2001 service data only)^[22]

1993–95 (8 V supply)

On these trucks the supply on the orange K7 wire is 8 V; the ground is K4 (black/light blue) and the signal is K24 (gray/black).^[13][14][16] The 1993 data says to look for a wiring fault if the supply is under 7 V.^[16]

1991–92 and 1996

1987–90 Renix (2-wire magnetic pickup)

Unverified The Renix sensor is a different design. Enthusiast references give 125–275 Ω across terminals A–B and at least about 0.5 V AC while cranking, and the 1988 service data gives the same resistance range. (third-party data and enthusiast sites only; no Renix factory manual in hand)^[2][3][24] Do both checks: a sensor can pass on resistance and still put out a weak signal.^[5]

The sensor’s part number changed several times. Each number below was checked against a Mopar dealer parts catalog and at least one independent catalog. Every original Mopar number for the XJ is now discontinued, so confirm the replacement by VIN with a dealer before buying.^[25][26][4]

"Verified" means a Mopar parts catalog plus an independent catalog list the number for that application. "2 catalogs" means two independent aftermarket or retailer catalogs agree; Mopar catalogs don't list aftermarket parts. All the original Mopar numbers are discontinued. Confirm by VIN with a dealer before buying.

Not yet verified

These numbers are listed somewhere but don't meet the bar yet. Each one says why. Don't order from this table without a VIN check.

• 1997–98 4.0L. We couldn’t find a Mopar catalog listing for these years. Crown lists 56027866AC for 1997–99 (with AB and AD as alternates) and AE as the replacement for 1997–2001, but the Mopar catalog shows AC for 1999 only and AE for 2000–01 only.^{[4][7][25][26]}
• Supersessions. A dealer listing shows 56027866AE superseding 56027866AD. Unverified An owner reports a dealer confirmed AC supersedes AB on a 1998. (forum report only)^[6]
• Unverified Some earlier XJs reportedly used a “high-altitude” CPS variant. (needs a Mopar catalog or FSM reference) ^[6]

1. Disconnect the sensor connector, then remove the two bolts (or nuts) and pull the sensor out of the bellhousing.^[15][19]
2. Fit the new sensor flush in its opening and tighten the bolts or nuts to 14 ft-lb (19 N·m).^[13][15][19]
3. Use the original bolts. They are specially machined to space the sensor from the flywheel; don’t substitute others.^[13][15][19]
4. If yours has a single adjustable bolt, the tip needs a paper spacer (PN 05252229). Push the sensor against the flywheel or drive plate before tightening; without the spacer the sensor breaks on first start.^[13][15][19]
5. Reconnect the connector and refit the harness clip.^[13]

• Renix trucks: Unverified the 18-51-88 update kit (83100066) adds a patch harness, and the bulletin specifies 16 ft-lb for the sensor bolts. (factory bulletin only)^[1]
• Don’t fit the sensor before installing a transmission: an owner warns the flexplate can damage it.^[6]