Diagnostic Aids

Perform this test only when directed by QUICK TEST or other test. This test is intended to diagnose the following:

• Crankshaft Position (CKP) sensor.
• CKP and SIG RTN harness circuits.
• PCM.

1. Check SIG RTN Circuit For Short To Power
   
   Turn ignition off. Disconnect CKP sensor harness connector (located near flywheel). Disconnect PCM harness connector. Measure resistance between SIG RTN and VPWR circuits at PCM harness connector. See Fig 1. See CIRCUIT PIN IDENTIFICATION  table. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair short in circuit.
2. Check CKP Circuit Continuity
   
   Measure resistance of CKP circuit between CKP sensor harness connector and PCM harness connector. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair open in circuit.
   Fig 1: Identifying Crankshaft Position Sensor Test Circuits

   Courtesy of FORD MOTOR CO.
3. Check CKP Circuit For Short To Ground
   
   Measure resistance between ground and CKP circuit at PCM harness connector. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair short in circuit.
4. Check CKP SIG RTN Circuit For Short To Power
   
   Measure resistance between CKP and VPWR circuits at PCM harness connector. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair short in circuit.
5. Inspect CKP Sensor Harness Shield
   
   Inspect CKP sensor harness shield for damage. Repair as necessary. Measure resistance between harness shield and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair open wiring harness shield.
6. Inspect Flywheel & CKP Sensor For Damage
   
   Inspect flywheel for chipped teeth and inspect CKP sensor for damage. Repair flywheel or CKP sensor as necessary. If flywheel and sensor are okay, go to next step.
7. Check CKP Sensor
   
   Disconnect CKP sensor connector. Measure resistance between CKP sensor connector terminals. If resistance is 512-632 ohms, replace PCM. If resistance is not 106.5-203.5 ohms, replace CKP sensor.