793F CMD Off-Highway Truck Caterpillar

Illustration 1	g02792319
Cat® and CAN data-link schematic

This diagnostic code is recorded when the VIMS^TM 3G Application ECM records an abnormal update rate from the Transmission ECM.

System Response:

This failure results in events that are logged against the VIMS 3G Application ECM that cannot be explained. Transmission ECM communication is not correct.

Test Step 1. VERIFY THE HARDWARE AND THE SOFTWARE PART NUMBERS

1. Verify that the following information is correct:

   • VIMS 3G Application ECM software part number

   • VIMS 3G Application ECM part number

   • Transmission ECM software part number

   • Transmission ECM part number

   Note: For the correct part configuration software numbers, consult the business unit that produces the product.

Expected Result:

All part numbers are correct.

Results:

• OK - All part numbers are correct. Proceed to Test Step 2.

• NOT OK - All part numbers are not correct. An ECM has the wrong part number or incorrect software.

  Repair: Replace the incorrect ECM with an ECM that has the correct part number. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  Flash the correct configuration software. See Testing and Adjusting, "Electronic Control Module (ECM) - Flash Program".

  STOP

Test Step 2. INSPECT THE HARNESS

1. Turn off the disconnect switch.

2. Inspect Cat data-link harness for the following:

   1. Inspect the connectors, pins, and sockets for the following:

      • Cleanliness

      • Security

      • Proper mating

      • Seal condition

      • Moisture

      • Corrosion

   2. Inspect the wires at the connector for the following:

      • Security

      • Nicks

      • Abrasion

      Note: Take care not to pull the wire out of the connector.

   3. Inspect the harness for the following:

      • Damage

      • Abrasion

      • Kinks

Expected Result:

The harness is in good condition.

Results:

• OK - The harness is in good condition. Proceed to Test Step 3.

• NOT OK - The harness is not in good condition.

  Repair: Repair or replace the harness.

  STOP

Test Step 3. CHECK FOR SHORTS TO GROUND

The disconnect switch remains off.

1. Disconnect all ECMs from the Cat data-link.

2. At the VIMS 3G Application ECM harness, measure the resistance between frame ground and connector contacts 8 (wire 893-GN(Green)) and 9 (wire 892-BR(Brown)) of the Cat® data-link circuit.

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. Proceed to Test Step 4.

• NOT OK - The resistance is less than 5000 ohms. There is a short between frame ground and the Cat data-link circuit.

  Repair: Repair or replace the harness.

  STOP

Test Step 4. CHECK FOR SHORT TO +BATTERY

The disconnect switch remains off. All related ECMs remain disconnected from the harness.

1. At the VIMS 3G Application ECM harness connector, perform the following checks:

   • Measure the resistance between the +Battery connector contact 52 (wire 170-RD(Red)) and connector contact 8 (wire 893-GN(Green)).

   • Measure the resistance between connector contact 52 (wire 170-RD(Red)) and connector contact 9 (wire 892-BR(Brown)).

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. Proceed to Test Step 5.

• NOT OK - The resistance is less than 5000 ohms. There is a short between the +battery and the Cat data-link circuit.

  Repair: Repair or replace the harness.

  STOP

Test Step 5. CHECK FOR OPEN HARNESS

The disconnect switch remains off. All related ECMs remain disconnected from the harness.

1. Check the continuity of the Cat data-link circuit:

   • Measure the resistance between VIMS 3G Application ECM connector contact 8 (wire 893-GN(Green)) and Transmission ECM connector contact J1-10 (wire 893-GN(Green)).

   • Measure the resistance between VIMS 3G Application ECM connector contact 9 (wire 892-BR(Brown)) and Transmission ECM connector contact J1-20 (wire 892-BR(Brown)).

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 6.

• NOT OK - The resistance is greater than 5 ohms. The Cat data-link circuit is open.

  Repair: Repair or replace the harness.

  STOP

Test Step 6. CHECK FOR ADDITIONAL DIAGNOSTIC CODES FOR THE OTHER ECM

1. Reconnect all of the ECMs.

2. Turn on the disconnect switch and the keyswitch.

3. Check for diagnostic codes logged against the other ECM.

Expected Result:

The other ECM does not have diagnostic codes.

Results:

• OK - The other ECM does not have diagnostic codes. The Transmission ECM may have failed, however, ECM failure is unlikely.

  Repair: Exit this procedure. Perform this procedure again. If the failure is not found, contact your Cat dealer. If ECM replacement is required, see the Testing and Adjusting, "Electronic Control Module (ECM) - Replace" Section of this manual.

  STOP

• NOT OK - The other ECM has diagnostic codes.

  Repair: Perform the troubleshooting procedure for the other diagnostic codes.

  STOP