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| Illustration 1 | g02748103 |
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Schematic of the connections for the System Voltage circuit | |
This diagnostic code is recorded when the system voltage is below 9 VDC. When this diagnostic code is recorded, diagnostic codes for multiple sensors may be displayed as well.
The possible causes of this diagnostic code are listed below:
- The wiring in the machine harness has failed.
- A charging system component has failed.
- The system has a low voltage.
- The Brake ECM may have failed. This situation is unlikely.
Test Step 1. CHECK THE BATTERY VOLTAGE.
- Start the engine and run at high idle for several minutes.
- Measure the battery voltage at the battery posts.
Expected Result:
Battery voltage should be greater than 9 VDC.
Results:
- OK - Battery voltage is greater than 9 VDC. Battery voltage is correct. Proceed to Test Step 2.
- NOT OK - Battery voltage is not greater than 9 VDC.
Repair: The charging system is not correct. Check the charging system. See Troubleshooting, "Charging System".
STOP
Test Step 2. CHECK THE SYSTEM VOLTAGE AT THE ECM.
- The engine must still be running at high idle.
- DO NOT DISCONNECT the machine harness from the ECM. At connector "J1" of the ECM, prepare to make a voltage measurement with a calibrated, digital multimeter.
- At the machine harness for the ECM, insert a multimeter probe into the back of connector "J1". Measure the voltage (VDC) between J1-31 (wire 176-RD(Red)) and J1-13 (wire A252-BK(Black)).
Expected Result:
Voltage should be greater than 9 VDC.
Results:
- OK - Voltage is greater than 9 VDC. Battery voltage is correct. Proceed to Test Step 3.
- NOT OK - Voltage is not greater than 9 VDC.
Repair: The machine harness is not correct. Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.
- Remove connectors "J1" and "J2" from the Brake ECM. Inspect the contacts and clean the contacts of the harness connectors.
- Reconnect all harness connectors.
- Turn the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 0168 FMI 04 diagnostic code is present.
Expected Result:
The CID 0168 FMI 04 Diagnostic code is present.
Results:
- YES - The CID 0168 FMI 04 diagnostic code is present.
Repair: The ECM may have failed. However, a failure of the Brake ECM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to the Testing and Adjusting, "Electronic Control Module (ECM) - Replace" Story in this manual for additional information.
STOP
- NO - The CID 0168 FMI 04 diagnostic code is not present.
Repair: The diagnostic code is not present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
STOP