793F CMD Off-Highway Truck/Tractor Braking System Caterpillar

Prior to replacement of the ECM, ensure that replacement is necessary. The ECM is seldom the cause of a diagnostic code. Always check that power is available to the ECM. Battery voltage is required between J1-31 and J1-13 of the machine harness connector for the ECM. Prior to replacing an ECM, always contact your dealerships Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time.

Note: The New Electronic Control Modules are either pre-programmed for a particular machine or the modules are not programmed. An unprogrammed electronic control module must be programmed by using the Caterpillar Electronic Technician (ET). See Testing and Adjusting, "Electronic Control Module - Flash Program". In order to determine that the ECM is programmed or that the ECM is not programmed, proceed to 6.

1. Turn the key start switch and the disconnect switch to the OFF position. Disconnect the machine harness from the ECM.

2. Remove the ECM.

3. Make sure that the new ECM has the correct part number.

4. Connect the machine harness to the replacement ECM.

5. Install the replacement ECM.

6. Determine if the replacement ECM is programmed or If the replacement ECM is not programmed. Programming the ECM can be done in two different ways. Proceed to 6.a or 6.b.

   1. Enter the component data display mode.

      If the display shows blanks, then the ECM is NOT programmed. See Testing and Adjusting, "Electronic Control Module - Flash Program".

      If the display shows the expected information, then the ECM is programmed. Proceed to 7.

   2. Connect the service tool for the Caterpillar Electronic Technician (ET) to the service connector for the data link of the machine. The ET service tool will communicate with the power train ECM.

      If the ECM is NOT programmed, the ET service tool will indicate the problem.

      If the ECM is programmed, the ET service tool provides access to the expected areas of the ECM.

7. Proceed to Testing and Adjusting, "Calibration". Perform ALL of the calibration and adjustment procedures.

   Note: Performance will be greatly affected if ANY of the calibration procedures are omitted. PERFORM ALL OF THE CALIBRATION PROCEDURES. Even if the replacement ECM was acquired from a similar machine, perform all calibration procedures.