CAT Comm Adapter3 478-0235 Diagnostics for Caterpillar
This code is generated when PL522 and 523 detect a battery voltage below 11 VDC.
Test Step 1. Check the system voltage at the 70-pin connector of the PL522 and 523 modules.
Start the engine and run it at high idle for 5 to 10 minutes. Measure the system voltage between the "No Switching Power" and "Ground" contacts. Pin 52 is the "No Switching Power" terminal, and pin 65 is the "Ground" terminal.
Expected Results: 24 VDC system voltage: 27 VDC to 29 VDC. 12 VDC system voltage: 13 VDC to 15 VDC. Results:
• Normal - Voltage is correct. Clear this diagnostic code and check for any other diagnostic codes. Stop.
• Abnormal - The voltage is abnormal. Proceed to Test Step 2.
Test Step 2. Check the alternator.
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Run the engine at high idle for 5 to 10 minutes. Measure the voltage output at the battery terminals.
Result: • Normal - Voltage is correct. Proceed to Test Step 3.
• Abnormal - The voltage is abnormal.
Repair: Repair or replace the alternator.
Stop Test Step 3. Check the battery voltage.
Turn the ignition switch to the off position. Measure the voltage at the battery terminals. Always wear appropriate personal protective equipment. Expected Result: For a 12 VDC system, the voltage should be 12 VDC to 15 VDC. For a 24 VDC system, the voltage should be 24 VDC to 27 VDC.
Results:
• Normal - Voltage between 12 VDC and 15 VDC, or between 24 VDC and 27 VDC.
Repair: PL522 or 523 may be faulty. Recheck the system before replacing PL522 or 523. PL522 or 523 are rarely the root cause of the problem. Refer to System Operation, Troubleshooting and Repair, Testing and Adjustment, "Electronic Control Module (ECM) - Replacement". After replacing PL522 or 523, recheck the system and check the status of diagnostic codes.
Stop • Abnormal - Voltage not between 12 VDC and 15 VDC, or between 24 VDC and 27 VDC.
Repair: Refer to the specific manual, REHS0354, "Charging System Troubleshooting and Repair". If the situation does not improve, PL522 or 523 may be faulty. Recheck the system before replacing PL522 or 523. PL522 or 523 are rarely the root cause of the problem. Please refer to System Operation, Troubleshooting and Troubleshooting, Testing and Adjustment, "Electronic Control Module (ECM) - Replacement". After replacing PL522 or 523, recheck the system and check the status of diagnostic codes.
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