C8.7 and C12.9 Marine Engines Caterpillar

Speed/Timing - Test

Usage:

C8.7 CS7

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Table 1
J1939 Code and Description	Comments
636-2 Engine Position Sensor : Erratic, Intermittent, or Incorrect	The camshaft position sensor signal is not stable. The camshaft position is intermittently detected. The code will be active if the Electronic Control Module (ECM) detects an abnormal signal.
636-8 Engine Position Sensor : Abnormal Frequency, Pulse Width, or Period	The camshaft position sensor signal is not detected within 4 camshaft revolutions. The code is deactivated and logged if normal camshaft position detection returns.
636-31 Engine Position Sensor : Condition Exists	The camshaft position sensor detects an abnormal timing pattern offset between the crankshaft signal and the expect camshaft position. The mechanical timing of the camshaft position is incorrect. The code is deactivated and logged if normal camshaft position detection returns. Refer to Testing and Adjusting, “Rear Gear Group-Time.
637-2 Engine Position Sensor : Erratic, Intermittent, or Incorrect	The crankshaft position sensor signal is not stable. The crankshaft position is intermittently detected by the engine ECM.
637-9 Engine Position Sensor : Abnormal Update Rate	The crankshaft position sensor signal is not detected by the engine ECM.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Start the engine. C. Run the engine until normal operating temperature is reached. Note: If the engine will not start, monitor the engine rpm on Cat ET when the engine is being cranked. If necessary, power Cat ET from another battery when the engine is being cranked. D. Look for these codes and pattern status parameters on Cat ET: Codes: • 636-2 • 636-8 • 637-2 • 637-9 Parameters: • "Engine Speed" •"Engine Speed Secondary Sensor" Note: When checking status parameters, engine must be in a cranking state.	Codes	Result: None of the diagnostic codes that are listed above are active or logged and the engine speed is detected. Repair: If the diagnostic codes that are listed above are not active or logged as well as the "Engine Speed and Secondary Engine Speed" sensor feedback status is showing a valid speed signal and the engine is not running properly, refer to the appropriate engine symptom in this Troubleshooting Manual. Result: If a 636-2 or a 637-2 code is active or logged. Proceed to Test Step 2. Result: Codes 636-8 or 637-9 code is active and no engine rpm is detected. Cat ET is not reporting engine rpm for at least one engine speed/timing sensor while the engine is cranked. Proceed to Test Step 3.
2. Check the Installation of the Sensor Assembly A. Turn the main disconnect switch to the OFF position. B. Visually inspect the sensors without removing the sensor assembly from the engine. Verify that the sensor is secure and the flange of the sensor is flush against the mounting surface. C. Remove the suspect engine speed/timing sensor from the engine. D. Ensure that the O-ring seals are installed and free of damage.	Sensor	Result: The O-ring seals are properly installed. The bracket and the seals are free of damage. Repair: Perform the following procedure: 1. Lubricate the O-ring seals with oil. 2. Fully seat the sensor into the housing. Note: If the sensor assembly will not fully seat into the engine, replace the sensor assembly. 3. Tighten the bolts. 4. Connect the connector. 5. Ensure that the harness is properly secured, and that the tie-wraps are placed in the correct location. Proceed to Test Step 3. Result: At least one of the sensor assembly components is NOT OK. Repair: Install a new sensor assembly. If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the connectors. Refer to Troubleshooting, Electrical Connectors-Inspect, for additional information. C. Perform a 45 N (10 lb) pull test on the connector wires. D. Check the harness for abrasions and pinch points.	Connectors and Wiring	Result: The connectors and wiring appear to be OK. Proceed to Test Step 4. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 4.

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Table 3
Troubleshooting Test Steps	Values	Results
4. Check the Supply Voltage to the Sensors A. Turn the main disconnect switch to the OFF position. B. Disconnect the connectors for the speed/timing sensors. C. Restore electrical power to the ECM. D. Measure the voltage at the sensor connectors between following terminals: Crankshaft Speed Timing Sensor:- Terminal 1 (Sensor Supply) and Terminal 2 (Sensor Return) Camshaft Speed Timing Sensor: Terminal 1 ( Sensor Return) Terminal 2 ( Sensor Supply)	Supply Voltage	Note: The sensor supply is 2.5VDC +\- .2 VDC. Result:The voltage is OK. The sensor supply is inside the 2.3 VDC to 2.7 VDC range. Proceed to Test Step 5. Result: The voltage is NOT OK. The sensor supply is outside of the 2.3 VDC to 2.7 VDC range. Proceed to Test Step 7.
5. Measure Speed Timing Sensor Resistance A. Turn the Keyswitch to the OFF position B. Disconnect and remove the affected Speed Timing Sensor 636 Code: Cam Position Sensor 637 Code: Crank Position Sensor C. Measure resistance between pins 1 and 2 Valid resistance measurement 850-870 Ohms.	Signal Voltage	Result: The sensor resistance is within 850-870 Ohms. Proceed to Test Step 6. Result: The sensor resistance is NOT within 850-870 Ohms. Repair: Replace the engine speed/timing sensor. If the problem is not resolved, proceed to Test Step 6.
6. Check Return Wire for an Open A. Turn the main disconnect switch to the OFF position. B. Remove the connector to the affected camshaft or crankshaft sensor. C. Measure the resistance between the following locations: Camshaft position sensor terminal 2 and ECM location J2-67. Crankshaft position sensor terminal 2 and ECM location J2-65	Signal Voltage	Result: There was less than 10 ohms of resistance between terminal 2 and the appropriate ECM connector pin. Proceed to Test Step 7. Result: More than 10 ohms of resistance was measured between the sensor connector and ECM connector. Repair: There is an open circuit in the wiring harness. Repair or replace the wiring harness.
7. Check Return Wire for a Short Circuit to Ground A. Turn the main disconnect switch to the OFF position. B. Remove the connector to the affected camshaft or crankshaft sensor. C. Measure the resistance between the following locations: Camshaft position sensor terminal 2 and Engine Ground Crankshaft position sensor terminal 2 and Engine Ground	Supply Voltage	Result: There was more than 100 K ohms of resistance between the sensor terminal 2 and engine ground. Repair: The signal wire is OK. There is no short circuit detected. Proceed to Test Step 8. Result: There was less than 100 K ohms of resistance between sensor terminal 2 and engine ground. Repair: There is a short to ground in the wiring harness. Repair or replace the wiring harness.
8. Check the Return Wire for a Pin to Pin Short Circuit A. Turn the keyswitch to the OFF position. B. Remove the connector to the affected camshaft or crankshaft sensor. C. Disconnect the J2 connector at the ECM. D. Measure the resistance between the following locations for the sensor: Crankshaft Return J2-65 and all ECM connector pins. Camshaft Return J2-67 and all ECM connector pins.	Short Circuit	Result: There were more than 100 K ohms of resistance between the Return pin at the ECM and all other pins in the ECM connector. There appears to be a problem with the ECM. Repair:Replace the ECM. Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Result: There were less than 100 K ohms of resistance between the signal pin at the ECM and all other pins in the ECM connector. Repair: There is a short circuit in the wiring harness. Repair or replace the wiring harness.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).