826G Landfill Compactor, 825G Soil Compactor, 824G Wheel Dozer and 980G Wheel Loader Power Train Electronic Control System Caterpillar

This diagnostic code is recorded when the ECM identifies a system voltage that is below 21.3 VDC.

Possible causes of this diagnostic code are listed:

• The charging system is charging at less than the expected voltage.

• There is high impedance between the battery and the ECM connection.

• There is high impedance between the ECM and the ground connection.

• This battery is low or disconnected.

System Response:

The machine response is listed:

• The functions of the transmission are disabled until the voltage is above 21.3 V and the direction switch is placed in neutral.

Note: Ensure that the diagnostic code is active and that the diagnostic code indicator is active.

Test Step 1. CHECK THE BATTERY VOLTAGE.

1. Start the engine.

2. Run the engine at high idle for several minutes.

3. Measure the battery voltage at the battery posts.

Expected Result:

The voltage should be greater than 21.3 DCV.

Results:

• YES - The voltage is greater than 21.3 DCV. The battery voltage is correct. Proceed to 2.

• NO - The voltage is less than 21.3 DCV. The charging system is not operating correctly.

  Repair: Check the charging system. Refer to Testing and Adjusting, "Starting And Charging System" in the Service Manual for the machine that is being serviced.

  Stop.

Test Step 2. CHECK THE SYSTEM VOLTAGE AT THE ECM.

1. Run the engine at high idle.

2. Locate the connector for the ECM.

3. Use 7X-1710 Multimeter Probe Group.

4. Measure the system voltage between J1-1 (wire 164-WH) and J1-2 (wire A273-BK), and measure the voltage between J1-6 (wire 164-WH) and J1-5 (wire A273-BK).

Expected Result:

The voltage should be less than 21.3 DCV.

Results:

• YES - The voltage is less than 21.3 DCV. The harness has failed.

  Repair: Repair the harness or replace the harness.

  Stop.

• NO - Voltage is greater than 21.3 DCV. The system voltage is correct.

  Repair: Ensure that the diagnostic code is active. Disconnect the harness connector from the ECM and inspect contacts J1-1, J1-2, J1-5, and J1-6 for corrosion or debris. Reconnect the harness connector to the ECM. If the diagnostic code is active, replace the ECM. See Testing and Adjusting, "Electronic Control Module (Power Train) - Replace".

  Stop.