Fault Condition: If the Engine Management System (EMS) Module calculates a significant difference between the Crank Speed Sensor input signal and the CAM Speed Sensor input signal, the EMS Module will turn on the Electronic Malfunction Lamp (EML) and SID 22 will set. If the engine speed signals agree, the fault will become inactive. The engine and tachometer will continue to operate when SID 22 is set because the EMS Module will use the CAM
Speed Sensor signal to calculate engine speed.
Note: Electrical problems can cause this fault to be generated, and electrical diagnostics are provided in this section. Mechanical problems can also cause temporary or permanent speed signal errors. After all electrical possibilities have been ruled out, check mechanical conditions that could cause vibration or signal errors. Such conditions include but are not limited to:
Faulty Engine Vibration Dampe, Contaminated sensor tips, Missing or chipped gear teeth, Improperly installed Flywheel Ring Gear, Incorrect Flywheel, Contaminated Flywheel Ring Gear, Improperly adjusted sensor
Excessive Driveshaft backlash, Improperly balanced engine components.
Possible repairs:
Turn the ignition key OFF first.
1) Disconnect the Crank Speed Sensor connector. On the sensor side of the harness connector, check for continuity between pin 1 and a good ground. Also check for continuity between pin 2 and a good ground. If continuity exists between either pin and ground, replace the sensor.
2) Disconnect connectors A and B from the EMS Module. Check for continuity between EMS Module connector A pin 38 and all other pins on EMS Module connectors A and B. If continuity exists between pin 38 and any other pin, pin 38 is shorted to one of the other EMS Module circuits. Locate and repair the short circuit to voltage in the connector. If there is NO continuity, the sensor signal line is shorted to voltage somewhere else in the harness. Locate and repair the short to voltage.
3) Disconnect connectors A and B from the EMS Module. Check for continuity between EMS Module connector A pin 37 and all other pins on EMS Module connectors A and B. If continuity exists between pin 37 and any
other pin, pin 37 is shorted to one of the other EMS Module circuits. Locate and repair the short circuit to voltage. If NO continuity exists, the return line is shorted to voltage somewhere else in the harness. Locate and repair the short circuit to voltage.
4) Disconnect the Crank Speed Sensor. Disconnect EMS Module connectors A and B. Check for continuity between EMS Module connector A pins 37 and 38 versus all other pins on EMS Module connectors A and B.
If continuity exists between pin 37 or pin 38 and any other pin, the suspect pin is shorted to one of the other EMS Module circuits. Locate and repair the short circuit.
5) Disconnect the Crank Speed Sensor. Disconnect EMS Module connectors A and B. Check for continuity between the circuit (connector A pin 37 or 38) that showed continuity in test 7 and all other pins on EMS Module connectors A and B. If continuity exists, the suspect pin is shorted to one of the other EMS Module circuits. Locate and repair the short circuit. If there is NO continuity, the suspect pin is shorted to ground somewhere else in the harness. Locate and repair the short circuit.
6) Connect the Crank Speed Sensor. Disconnect EMS Module connector A. Measure the resistance between EMS Module connector A pins 37 and 38. If the resistance is not within this range, there is an open circuit or high resistance connection at the sensor harness connector. Repair the connector if possible, otherwise, replace the sensor.
7) Connect the Crank Speed Sensor connector. Connect EMS Module connectors A and B. Start the engine. If SID 22 is still active, check the Engine Management System (EMS Module) and connectors for dirt, loose or broken pins, or repairable damage. If no problems are evident, or they are not repairable, replace the EMS Module and retest the system. If SID 22 is NOT active, the diagnostic procedures have corrected the problem.
Check all connectors to ensure proper connections.
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