HOSE & TUBE AS 5079917 - Caterpillar

Note: A -4 diagnostic code can indicate either an actual short to ground or an open circuit.Expected Result:None of the above diagnostic codes are active.Results:
OK - None of the above codes are active at this time.Repair: The problem appears to be resolved. The original diagnostic code may have been caused by a poor electrical connection in one of the harness connectors. If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Symptom Troubleshooting" for the appropriate test procedure.If any of these codes are logged and the engine is running properly, there may be an intermittent electrical problem. Check for an intermittent problem in a connector or on a wiring harness between the sensor and the ECM. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting information.STOP
Not OK - A -3 or -4 diagnostic code that is related to the detonation sensors was activated.Repair: There is an electrical problem in one of the circuits for the detonation sensors. Record the diagnostic code and the location of the suspect detonation sensor.Proceed to Test Step 4.Test Step 4. Check for a Supply Voltage at the Sensor Connector
Set the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
Disconnect the harness connector for the suspect detonation sensor.
Restore the electrical power to the engine. Set the engine control switch to the STOP position.
Use a multimeter to measure the voltage between terminals A and B on the harness side of the connector for the suspect sensor. Expected Result:The supply voltage at the harness connector is 8.0 0.4 VDC.Results:
OK - The supply voltage at the harness connector is 8.0 0.4 VDC. The correct voltage is available to the sensor. Leave the sensor disconnected from the harness. Proceed to Test Step 5.
Not OK - The supply voltage at the harness connector is not 8.0 0.4 VDC.Repair: The correct supply voltage is not available to the sensor. There is probably an open circuit in the 8 V supply or in the return for the sensor. The open circuit may be caused by a poor electrical connection or a wiring problem. Check the harness between the ECM and the harness connector for the sensor for an intermittent electrical problem.If only one detonation sensor has a diagnostic code, the open circuit for the 8 V supply is in the engine harness. Repair the electrical connection and/or the wiring, when possible. Replace the harness, if necessary. Verify that the original problem has been resolved.STOPTest Step 5. Measure the Voltage on the Signal Wire at the Harness Connector
Measure the voltage between terminals B and C on the harness side of the connector for the suspect sensor. Expected Result:The voltage is between 0.4 VDC and 0.6 VDC.Results:
OK - The voltage is between 0.4 VDC and 0.6 VDC.Repair: Connect the suspect sensor. Start the engine again and check for the diagnostic code.If the diagnostic code is still active, replace the detonation