26SI Series Alternator – MID 161 – CID 0254 – FMI 04

Conditions Which Generate This Code:

Communication will not occur when power to the PL522 or 523 is below 10.5 VDC. The PL522 or 523 will still communicate with Caterpillar Electronic Technician (Cat ET ) when power to the module is down to 9 VDC. A diagnostic code of “CID 168 FMI 01” will occur when the system voltage drops below 11 VDC. A diagnostic code of “CID 254 FMI 04” will occur when the system voltage drops below 9 VDC. This CID code is logged so that no messages will be communicated from the machine to the office.

Test Step 1. CHECK THE SYSTEM VOLTAGE AT THE PL522 and 523.

  1. Start the engine and operate the engine at a high idle for 5 to 10 minutes.
  1. Measure the system voltage between the “Unswitched Power” and the “Ground” contacts. Pin 52 is the terminal for “Unswitched Power” and pin 65 is the terminal for “Ground”.

Expected Result:

The voltage is 11 VDC to 32 VDC.

Results:

  • OK – The voltage is 11 VDC to 32 VDC. The PL522 and 523 should not be logging this diagnostic code.

    Repair: Use Cat ET in order to clear the diagnostic code from the PL522 and 523. If the voltage is correct and the PL522 and 523 records the diagnostic code again, Replace the PL522 and 523. Before replacing the PL522 and 523, contact your Caterpillar Technical Communicator.

    STOP

  • NOT OK – The voltage is not 11 VDC to 32 VDC. Proceed to Test Step 2.

Test Step 2. CHECK THE ALTERNATOR.

  1. Run the engine at high idle for 5 to 10 minutes.
  1. Measure the voltage output at the battery posts.

Expected Result:

The voltage should be below 32 VDC.

Results:

  • OK – The voltage is below 32 VDC. The battery could be faulty. Proceed to Test Step 3.

  • NOT OK – The voltage is above 32 VDC. Repair the alternator or replace the alternator. The voltage regulator could be faulty. If conditions are not resolved, proceed to Test Step 3.

Test Step 3. CHECK THE BATTERY VOLTAGE.

Turn the keyswitch to the OFF position. Measure the battery voltage at the battery posts.

Expected Result:

The voltage should be below 32 VDC.

Results:

  • OK – The voltage is below 32 VDC. Proceed to Test Step 4.

  • NOT OK – The voltage is above 32 VDC.

    Repair: See Special Instruction, REHS0354, “Charging System Troubleshooting”.

    If conditions are not resolved, proceed to Test Step 4.

Test Step 4. CHECK EVERY ECM ON THE MACHINE.

Check the logged diagnostics of any other ECM that is installed on the machine. Compare each ECM that has logged the”CID 168 FMI 00″ code in the same time period. The Diagnostic Clock Hours (DCH) on the logs may be different. The difference between the current DCH and the logged DCH is important.

Expected Result:

Other “CID 168 FMI 00” diagnostic codes can be found on other Electronic Control Modules (ECM).

Results:

  • YES – “CID 168 FMI 00” diagnostic codes are found on other Electronic Control Modules (ECM).

    Repair: Clear the fault if all the following conditions occur:

    • A problem is not found with the charging system.

    • A problem is not found with the wiring.

    • The fault has occurred a few times.

    Monitor the module and the machine for further occurrences. If the fault occurs again, the PL522 or 523 module has not failed as other electronic control modules are displaying the same fault. Recheck the system voltage.

    STOP

  • NO – No other “CID 168 FMI 00” diagnostic codes can be found on other electronic control modules.

    Repair: Clear the fault if all the following conditions occur:

    • A problem is not found with the charging system.

    • A problem is not found with the wiring.

    • The fault has occurred a few times.

    Monitor the module and the machine for further occurrences. If the fault occurs again, then the PL522 or 523 module is possibly faulty. The PL522 or 523 should be replaced. Refer to Systems operation, Troubleshooting, Testing and Adjusting, “Electronic Control Module (ECM) – Replace”. If the PL522 or 523 has been replaced, recheck the system and check the status of the diagnostic code.

    STOP

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