C7.1 Engines For Caterpillar Built Machines Caterpillar

This procedure covers the following codes:

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.

The engine uses two engine speed/timing sensors. The primary speed/timing sensor is located 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 located 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 located 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 from the primary sensor and the secondary sensor during operation of the engine will cause fuel injection to be terminated. The engine will stop.

The primary sensor and the secondary sensor are interchangeable components. If a sensor is suspect, the sensors can be exchanged in order 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.

Illustration 1	g01878676
Schematic for the speed/timing sensors

Illustration 2	g01980993
View of the 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

Illustration 3	g02474338
View of the sensor locations (1) Primary speed/timing sensor (2) Secondary speed/timing sensor

Illustration 4	g01212995
Typical example of a speed/timing sensor (1) 8 VDC Supply (2) Signal

Test Step 1. Inspect the Electrical Connectors and the Harness

1. Turn the keyswitch to the OFF position.

2. Inspect the connectors for the speed/timing sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect".

3. 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.

4. Check that the ground connection on the ECM and the negative terminal on the battery are correctly installed.

5. Check the ground connection on the ECM for abrasions and pinch points.

6. Check the screws for the ECM connector for the correct torque of 6 N·m (53 lb in).

7. Check the harness for abrasion and pinch points from the suspect sensor to the ECM.

8. Check that the suspect sensor is installed correctly. Check that the suspect sensor is fully seated into the engine. Check that the sensor is securely latched.

Expected Result:

The electrical connectors and the cables are correctly installed.

Results:

• The harness is OK. - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the faulty connectors or the harness and/or replace the faulty connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly coupled.If the primary speed/timing sensor must be replaced or the sensor must be reinstalled, refer to Disassembly and Assembly, "Crankshaft Position Sensor - Remove and Install". If the secondary speed/timing sensor must be replaced or the sensor must be reinstalled, refer to Disassembly and Assembly, "Camshaft Position Sensor - Remove and Install".Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault.

  STOP

Test Step 2. Check for Active Diagnostic Codes and Recently Logged Diagnostic Codes

1. Turn the keyswitch to the OFF position.

2. Connect the electronic service tool to the diagnostic connector.

3. Turn the keyswitch to the ON position. If the engine will start, then run the engine.

4. Use the electronic service tool in order to monitor active diagnostic codes or recently logged diagnostic codes.

Results:

• Diagnostic codes 190-8 or 723-8 are active or recently logged. - Proceed to Test Step 5.

• Diagnostic codes 678-3 or 678-4 are active or recently logged. - Proceed to Test Step 5.

• Diagnostic code 637-11 is active or recently logged. - Proceed to Test Step 3.

• No active diagnostic codes or recently logged diagnostic codes are displayed. -
  
  STOP

Test Step 3. Inspect the Sensors

1. Ensure that the speed/timing sensors are correctly seated in the cylinder block and 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".

2. Use the electronic service tool to check if the 637-11 diagnostic code is still active.

Results:

• A 637-11 diagnostic code is still active at this time. - Proceed to Test Step 4.

• A 637-11 diagnostic code is not active at this time. - Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.STOP

Test Step 4. Check the Crankshaft Timing Ring and the Timing Ring on the Camshaft

1. 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".

2. Use a flashlight in order to check the timing ring on the camshaft through the camshaft timing hole for damage.

3. Use a flashlight in order 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.

Results:

• Found fault 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 in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault.

  STOP

• No faults found - Repeat this procedure from Test Step 3.

Test Step 5. Measure the Supply Voltage at the Sensor Connector

1. Turn the keyswitch to the OFF position.

2. Disconnect the speed/timing sensor with the active diagnostic code.

3. Measure the voltage from terminal 1 on the sensor connector to engine ground.

   Note: The voltage should read 7.5 to 8.5 VDC.

Expected Result:

The readings agree with the values that are listed above.

Results:

• OK - The sensor is receiving the correct supply voltage. Proceed to Test Step 7.

• Not OK - There is a fault with the 8 VDC supply.

  Repair: Repair the faulty connectors or the harness. Replace the faulty connectors or the harness. Reconnect all sensor and ECM connectors. Ensure that all of the seals are correctly in place. Ensure that all connectors are correctly coupled.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair has eliminated the fault.

  STOP

Test Step 6. Disconnect the Power Supply Connections for the Speed/Timing Sensors at the ECM

1. Turn the keyswitch to the OFF position.

2. Disconnect connector P2. Thoroughly inspect the P2/J2 connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for more information.

3. Remove the P2:44 (+8 V).

4. Reconnect the P2 connector to the ECM.

5. Turn the keyswitch to the ON position.

6. Use the electronic service tool to check for active diagnostic codes.

Expected Result:

One of the following diagnostic codes is still active after the terminals for sensor power have been disconnected:

• 678-3 ECU 8 Volts DC Supply : Voltage Above Normal

• 678-4 ECU 8 Volts DC Supply : Voltage Below Normal

Results:

• OK -

  Repair: Perform the following repair: Check the battery voltage at pins 61, 63, 65, 67 and 69 (Battery ground) on the P1 connector. Check the battery voltage at pins 48, 52, 53, 55 and 57 (Battery+) on the P1 connector.. The measured voltage should be between 22.0 VDC and 27.0 VDC.If the voltage is correct, then perform the following procedure.

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Contact the Technical Communicator at a Caterpillar dealer.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  4. Use the electronic service tool to recheck the system for active diagnostic codes.

  5. If the fault is resolved with the test ECM, reconnect the suspect ECM.

  6. If the fault returns with the suspect ECM, replace the ECM.

  7. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

• Not OK -

  Repair: Perform the following repair:There is a fault in the harness between the ECM and the speed/timing sensors. While active diagnostic codes are being monitored, connect the removed wires one at a time in order to verify that the active diagnostic codes reappear. Replace pin P2:44 (+8 V). This procedure is used to find the wire that is causing the fault. Repair the harness or replace the harness, as required.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 7. Exchange the Sensors

1. Turn the keyswitch to the OFF position.

2. 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".

3. Turn the keyswitch to the ON position.

4. Start the engine.

5. Use the electronic service tool to check for active diagnostic codes. Wait for 30 seconds in order for diagnostic codes to become active.

Expected Result:

One of the following conditions exists:

• A 190-8 diagnostic code was previously active. A 723-8 diagnostic code is now active.

• A 723-8 diagnostic code was previously active. A 190-8 diagnostic code is now active.

Results:

• OK - The active diagnostic code is now for the other speed/timing sensor.

  Repair: Perform the following repair:

  1. Turn the keyswitch to the OFF position.

  2. Disconnect the suspect sensor and remove the suspect sensor from the engine.

  3. 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".

  4. Turn the keyswitch to the ON position.

  5. Start the engine.

  6. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.

  STOP

• Not OK - The diagnostic code that was previously active is still active. Proceed to Test Step 8.

Test Step 8. Bypass the Signal Wire for the Speed/Timing Sensor

1. Turn the keyswitch to the OFF position.

2. Disconnect the P2 connector. Disconnect the connector for the suspect speed/timing sensor.

3. For a 190-8 diagnostic code, remove the wire from P2:38. For a 723-8 diagnostic code, remove the wire from P2:39.

4. Remove the wire from terminal 2 of the connector for the speed/timing sensor.

5. Fabricate a jumper wire that is long enough to reach from the connector for the speed/timing sensor to the P2 connector.

6. Insert one end of the jumper wire into terminal 2 on the connector for the speed/timing sensor. Insert the other end of the jumper wire into the terminal for the signal of the speed/timing sensor on the P2 connector.

7. Reconnect the P2 connector and the connector for the speed/timing sensor.

8. Turn the keyswitch to the ON position.

9. Start the engine. If the engine will start, then run the engine.

10. Use the electronic service tool to check for active diagnostic codes. Wait for 30 seconds in order for diagnostic codes to become active.

Expected Result:

There are no active diagnostic codes.

Results:

• OK - The fault is in the harness.

  Repair: Repair the faulty connectors or replace the faulty connectors. Repair the faulty harness or replace the faulty harness. Reconnect all sensor and ECM connectors. Ensure that all of the seals are correctly in place. Ensure that all connectors are correctly coupled.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

• Not OK - The XXX-8 diagnostic code for the speed/timing sensor is still active. Remove all jumper wires and replace all wires to the original configuration. Proceed to Test Step 9.

Test Step 9. Check if the Replacement of the ECM Eliminates the Fault

1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

2. Contact the Technical Communicator at a Caterpillar dealer.

   Note: This consultation can greatly reduce the repair time.

3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

4. Use the electronic service tool to recheck the system for active diagnostic codes.

Results:

• The fault is eliminated. -

  Repair: Perform the following procedure:

  1. Reconnect the suspect ECM.

  2. If the fault returns with the suspect ECM, replace the ECM.

  3. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

• The fault was not resolved with a test ECM. -

  Repair: Repeat this diagnostic process. If the fault persists, the fault may be a damaged timing ring. Check the timing ring and/or replace the timing ring. Refer to Disassembly and Assembly, "Crankshaft Timing Ring - Remove and Install".Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP