Test JD: Crankshaft Position Sensor: Testing

1) Check CKP Signal Sent To PCM

Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Select RPM PID. Disable inertia switch and crank engine or crank engine at WOT (make certain engine will not start). Is engine RPM displayed on scan tool while cranking? If yes, CKP, PCM and harness working properly. Concern is elsewhere. See TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article. If no, go to next step.

2) Check Timing Cover, CKP Sensor & External Trigger Wheel (Outside Timing Cover) For Obvious Physical Damage

Turn ignition switch to OFF position. Visually inspect the timing cover, CKP sensor and external trigger wheel for obvious physical damage. Do any parts appear physically damaged? If yes, repair or replace damaged parts. If no, go to next step.

3) Check For Proper CKP Bias Voltages In PCM

Disconnect CKP sensor. Turn ignition switch to ON position. Measure voltages of CKP(+) and CKP (-) circuits individually between the CKP harness connector and battery negative terminal. See Figure-Figure . Is each measurement 1.0-2.0 volts? If yes, go to next step. If no, go to step 8).

NOTE: CKP sensor resistance values change significantly with temperature rise.

4) Check CKP Sensor Resistance
Measure CKP sensor resistance between the (+) and (-) terminals. Is resistance 250-1000 ohms? If yes, go to next step. If no, replace CKP sensor and perform PCM RESET PROCEDURE under CLEARING CODES under SELF-DIAGNOSTIC SYSTEM.

NOTE: The harness shield protects the CKP signal from electrical noise and is grounded at one end, typically near the PCM.

5) Check CKP Circuit Harness Shield Ground
Measure the resistance between the CKP harness shield and battery negative terminal. Measure at the closest possible location to the CKP sensor. Is resistance less than 5 ohms? If yes, go to next step. If no, repair open circuit or poor ground connection.

NOTE: On vehicles equipped with 150-pin PCMs and PATS (Passive Anti-Theft System), disconnect only the Engine (E) harness connector. The engine may not crank if the Transmission (T) and Body (B) connectors are disconnected.

6) Check For Short Between CKP(+) & CKP(-) In Harness
Turn ignition switch to OFF position. Disconnect PCM. Measure resistance across the CKP(+) and CKP(-) pins at the CKP harness connector. Is resistance less than 10 k/ohms? If yes, REPAIR short circuit. If no, go to next step.

7) Crank Engine & Check CKP Sensor Amplitude At PCM Harness Connector

Set DVOM on low voltage AC scale. Measure voltage between CKP(+) and CKP(-) at the PCM while cranking engine. Allow voltage to stabilize. Was voltage reading greater than 0.3 volts AC? If yes, replace PCM. If no, replace CKP sensor and perform PCM RESET PROCEDURE under CLEARING CODES under SELF-DIAGNOSTIC SYSTEM.

NOTE: On vehicles equipped with 150-pin PCMs and PATS (Passive Anti-Theft System), disconnect ONLY the Engine (E) harness connector.

8) Check For Open In CKP Harness
Turn ignition switch to OFF position. Disconnect PCM. Measure resistance of CKP(+) and CKP(-) circuits individually between the PCM harness connector and the CKP harness connector. Is either resistance measurement greater than 5 ohms? If yes, repair open circuit. If no, go to next step.

9) Check For Short To Ground In CKP Harness

Measure resistance of CKP(+) and CKP(-) circuits individually between the CKP harness connector and battery negative terminal. Is either resistance measurement less than 10 k/ohms? If yes, repair short circuit. If no, go to next step.

10) Check For Short To Power In CKP Harness

Turn ignition switch to ON position. Measure voltage of CKP(+) and CKP(-) circuits individually between the PCM harness connector and battery negative terminal. Is either voltage measurement greater than 2.0 volts? If yes, repair short circuit. If no, replace PCM.