3516C High Displacement Engine Caterpillar

Use this procedure to troubleshoot a problem with one or more of the engine speed/timing sensors. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

Table 1

J1939 Code and Description	CDL Code and Description	Comments
190-8 Engine Speed : Abnormal Frequency, Pulse Width, or Period	190-8 Engine Speed : Abnormal Frequency, Pulse Width, or Period	The Electronic Control Module (ECM) can default to the secondary engine speed/timing sensor. The default will occur if a valid signal is not received from the primary engine speed/timing sensor. The engine will shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal. The code is logged.
723-8 Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period	342-8 Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period	If a valid signal is not received from the secondary engine speed/timing sensor, the ECM will default to the primary engine speed/timing sensor. The engine will shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal. The code is logged.

Illustration 1	g03846847
All of the electrical connectors may not be shown. Refer to the electrical schematic.

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 while the engine is being cranked. If necessary, power Cat ET from another battery while the engine is being cranked. D. Determine if a code is active or logged.	Codes	Result: A -8 code is not active or logged. Repair: Refer to the appropriate engine symptom in this Troubleshooting manual. Result: A -8 code is active or logged. Proceed to Test Step 2. Result: No engine rpm. 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. C. Remove the 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 of the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 4.
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: - Terminal A and Terminal B	Supply Voltage	Result: The battery voltage is OK. Proceed to Test Step 5. Result: The battery voltage is NOT OK. Proceed to Test Step 7.
5. Check the Signal Voltage at the Sensor A. Crank the engine and measure the voltage at the sensor connectors between following: - Signal wire and Terminal B	Signal Voltage	Result: The signal voltage is OK. The voltage measures less than 3 VDC or more than 9 VDC when the ECM is powered and the engine is not cranking. While the engine is cranking, the voltage is between 2 VDC and 7 VDC. Proceed to Test Step 6. Result: The signal voltage is NOT OK. Repair: Replace the engine speed/timing sensor. A timing calibration is not required when the sensors are replaced. If the problem is not resolved, proceed to Test Step 6.
6. Check the Signal Voltage at the ECM A. Turn the main disconnect switch to the OFF position. B. Remove the signal wire from the ECM connector P2-35. C. Restore electrical power to the ECM. D. Crank the engine and measure the voltage between the following: - Primary sensor signal wire and P1-18 E. Turn the main disconnect switch to the OFF position. F. Remove the signal wire from the ECM connector P2-46. G. Restore electrical power to the ECM. H. Crank the engine and measure the voltage between the following: - Secondary sensor signal wire and P1-5	ECM Signal Voltage	Result: The signal voltage is OK. The voltage measures less than 3 VDC or more than 9 VDC when the ECM is powered and the engine is not cranking. While the engine is cranking, the voltage is between 2 VDC and 7 VDC. Proceed to Test Step 7. Result: The signal voltage is not OK. There is a problem between the ECM and the engine speed/timing sensor. Repair: Repair or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 7.
7. Check the Supply Voltage for the Engine Speed/Timing Sensors at the ECM A. Turn the main disconnect switch to the OFF position. B. Remove the supply wire from ECM connector P2-29. Install a wire jumper into the socket P2-29. C. Reconnect ECM connector J2/P2. D. Restore electrical power to the ECM. E. Measure the supply voltage between the following: - P2-5 (ECM connector) and P2-29 (jumper wire)	ECM Supply Voltage	Result: The supply voltage is OK. There is an open circuit or a short circuit between the ECM and the connectors for the engine speed/timing sensors. Repair: Repair or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminated the problem. Result: The supply voltage is not OK. There appears to be a problem with the ECM. Repair: Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminated the problem.

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).