C7.1 Engines and Generator Sets Caterpillar

Speed/Timing - Test

Usage:

C7.1 770

This procedure covers the following diagnostic codes:

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Table 1
Diagnostic Codes for the Speed/Timing Sensors
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
190-8	190-8	Engine Speed : Abnormal Frequency, Pulse Width, or Period	The Electronic Control Module (ECM) detects the following conditions: An intermittent loss of signal or a complete loss of signal from the primary speed/timing sensor for 2 seconds The engine has been running for more than 3 seconds. 3512 or 3483 diagnostic trouble codes are not active. The warning light will come on and the diagnostic code will be logged. The ECM will use the signal from the secondary speed/timing sensor. The engine will be derated. If the signal from the secondary speed/timing sensor is also lost, the engine will stop.
723-8	342-8	Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width or Period	The Electronic Control Module (ECM) detects the following conditions: A loss of signal from the secondary speed/timing sensor for 2 seconds while the signal from the primary speed/timing sensor remained valid The engine has been running for more than 3 seconds. 3512 or 3483 diagnostic trouble codes are not active. The warning lamp will come on and the diagnostic code will be logged. The loss of signal from the secondary speed/timing sensor will prevent the engine from starting.
637-11	261-11	Engine Timing Sensor : Other Failure Mode	The Electronic Control Module (ECM) detects the following conditions: The outputs from the primary speed/timing sensor and the secondary speed/timing sensor differ by more than 8 degrees of crankshaft rotation. The engine has been running for more than 5 seconds. Diagnostic code 190-8 is not active. 3512 or 3483 diagnostic trouble codes are not active. The warning light will come on. This code will not be logged.

Use this procedure when the engine will not start and the electronic service tool indicates a faulty sensor by displaying "Not Detected" against the faulty sensor on the "No Start Parameter" screen.

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Illustration 1	g03796519
Typical examples of the sensor locations (1) Primary speed/timing sensor (2) Secondary speed/timing sensor

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Illustration 2	g03796527
Speed/timing sensor (1) 8 VDC Supply (2) Signal

The engine uses two engine speed/timing sensors. The primary speed/timing sensor is on the left-hand side of the cylinder block close to the flywheel housing. The primary speed/timing sensor generates a signal by detecting the movement of the teeth that are on the crankshaft timing ring. The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM uses the signal from the speed/timing sensor to calculate the position of the crankshaft. The signal is also used to determine the engine speed.

The secondary speed/timing sensor is on the right-hand side of the cylinder block toward the rear of the engine. The secondary speed/timing sensor generates a signal that is related to the camshaft position. The secondary speed/timing sensor detects the movement of the teeth on the timing ring for the camshaft. The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM calculates the speed and the rotational position of the engine by using the signal. The secondary speed/timing sensor is required for starting purposes.

During normal operation, the secondary speed/timing sensor is used to determine the cycle that the engine is on. When the timing has been established, the primary speed/timing sensor is then used to determine the engine speed and the angular position.

The loss of signal to the primary sensor and/or the secondary sensor will result in one of the following faults:

The engine will continue to run when only one sensor signal is present from either the primary sensor or the secondary sensor.
Loss of signal both sensors during operation of the engine will cause fuel injection to be terminated and the engine will stop.

The primary sensor and the secondary sensor are interchangeable components. If a sensor is suspect, the sensors can be exchanged to eliminate a fault. If a secondary sensor is suspect and a replacement secondary sensor is not available, then the primary sensor and the secondary sensor can be exchanged. This exchange will allow testing to determine if the secondary sensor is faulty.

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Illustration 3	g06156508
Schematic for the speed/timing sensors

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Illustration 4	g01980993
Pin locations for the speed/timing sensor on the P2 connector (44) Supply for the speed/timing sensor (8 VDC) (38) Signal for the primary speed/timing sensor (39) Signal for the secondary speed/timing sensor

Complete the procedure in the order in which the steps are listed.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Turn the keyswitch to the OFF position. B. Inspect the connectors for the speed/timing sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect". C. Perform a 45 N (10 lb) pull test on each of the wires in the suspect sensor connector and the sensor connections at the ECM. D. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). E. Check the ground connection on the ECM for abrasions and pinch points. F. Check the harness for abrasion and pinch points from the suspect sensor to the ECM. G. Check that the suspect sensor is installed correctly. Check that the suspect sensor is fully seated into the engine.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. Proceed to Test Step 2.
2. Check For Active Diagnostic Codes A. Turn the keyswitch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the keyswitch to the ON position. If the engine will start, then run the engine. D. Use the electronic service tool to monitor active diagnostic codes or recently logged diagnostic codes. E. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: Diagnostic code 637-11 (261-11) is active or recently logged. Proceed to Test Step 3. Result: Diagnostic code 190-8 or 723-8 (342-8) is active or recently logged. Proceed to Test Step 5.
3. Inspect the Sensors A. Ensure that the speed/timing sensors are correctly seated in the cylinder block. Ensure that the retaining bolts are tightened to a torque of 22 N·m (16 lb ft). Ensure that the speed/timing sensors are not damaged. Replace any damaged sensors. Refer to Disassembly and Assembly, "Crankshaft Position Sensor - Remove and Install" or refer to Disassembly and Assembly, "Camshaft Position Sensor - Remove and Install". B. Turn the keyswitch to the ON position. If the engine will run, then run the engine. C. Use the electronic service tool to check if the 637-11 (261-11) diagnostic code is still active.	Faulty sensor	Result: A 637-11 (261-11) diagnostic code is no longer active. Use the electronic service tool to clear all logged diagnostic codes. Return the engine to service. Result: A 637-11 (261-11) diagnostic code is still active. Proceed to Test Step 4.
4. Check the Crankshaft Timing Ring and the Timing Ring on the Camshaft A. Remove the primary speed/timing sensor and the secondary speed/timing sensor. Refer to Disassembly and Assembly, "Crankshaft Position Sensor - Remove and Install" or refer to Disassembly and Assembly, "Camshaft Position Sensor - Remove and Install". B. Use a flashlight to check the timing ring on the camshaft through the camshaft timing hole for damage. C. Use a flashlight to check the crankshaft timing ring for damaged teeth or missing teeth. Ensure that the crankshaft timing ring has not been displaced from the crankshaft.	Loose timing ring or damaged teeth	Result: Fault identified with the crankshaft timing ring or the timing ring on the camshaft. Repair: If necessary, replace the camshaft. Refer to Disassembly and Assembly, "Camshaft - Remove" and refer to Disassembly and Assembly, "Camshaft - Install". If necessary, replace the crankshaft timing ring. Refer to Disassembly and Assembly, "Crankshaft Timing Ring - Remove and Install". Use the electronic service tool to clear all logged diagnostic codes and then verify that the repair has eliminated the fault. Result: No faults found. Repeat this procedure from Test Step 3.
5. Measure the Supply Voltage at the Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the speed/timing sensor with the active diagnostic code. C. Turn the keyswitch to the ON position. D. Measure the voltage from terminal 1 on the sensor connector to engine ground.	7.5 VDC to 8.5 VDC	Result: The sensor supply voltage is not within the expected range - The fault is in the sensor supply wiring between the sensor and the ECM. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The sensor supply voltage is correct. Proceed to Test Step 6.
6. Exchange the Sensors A. Turn the keyswitch to the OFF position. B. Exchange the primary speed/timing sensor with the secondary speed/timing sensor. Refer to Disassembly and Assembly, "Crankshaft Position Sensor - Remove and Install" and refer to Disassembly and Assembly, "Camshaft Position Sensor - Remove and Install". C. Turn the keyswitch to the ON position. D. Start the engine. E. Use the electronic service tool to check for active diagnostic codes. Wait for 30 seconds in order for diagnostic codes to become active.	A 190-8 diagnostic code was previously active. A 723-8 (342-8) diagnostic code is now active. OR A 723-8 (342-8) diagnostic code was previously active. A 190-8 diagnostic code is now active.	Result: The active diagnostic code is now for the other speed/timing sensor. Repair: Turn the keyswitch to the OFF position. Disconnect the suspect sensor and remove the suspect sensor from the engine. Install a replacement sensor. Refer to Disassembly and Assembly, "Crankshaft Position Sensor - Remove and Install" or refer to Disassembly and Assembly, "Camshaft Position Sensor - Remove and Install". Turn the keyswitch to the ON position and start the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The diagnostic code that was previously active is still active. Proceed to Test Step 7.
7. Check the Signal Wire for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector. Disconnect the connector for the suspect speed/timing sensor. C. Check the resistance between terminal 2 on the harness connector for the sensor and the appropriate terminal on the P2 connector. Refer to Illustration 3.	Less than 2.0 Ohms	Result: The resistance is greater than 2.0 Ohms - There is an open circuit or high resistance in the signal wire. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The resistance is less than 2.0 Ohms. Proceed to Test Step 8.
8. Check the Signal Wire for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector. Disconnect the connector for the suspect speed/timing sensor. C. Check the resistance between the suspect sensor signal terminal and all other terminals on the P2 connector. Refer to Illustration 4.	Greater than 100 Ohms	Result: At least one of the resistance measurements is less than 100 Ohms. The fault is in the sensor signal wiring. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: All resistance measurements are greater than 100 Ohms. Contact the Dealer Solutions Network (DSN).