DIFFERENTIAL GP 2A6709 - Caterpillar

Illustration 1 g02143107
Connections of the Cat Data Link
This diagnostic code is associated with the communication across the Cat Data Link between the Power Train ECM and the Engine ECM.The FMI 09 means that the Power Train ECM is not receiving expected communication from the Engine ECM.The possible causes of this diagnostic code are listed:
An open circuit or a poor connection in the Cat Data Link between the Engine ECM and the Power Train ECM.
The Power Train ECM has failed. An ECM failure is unlikely.Cat Data Link diagnostic codes can be activated by more than one ECM depending on the location of a problem in the circuit. This procedure assumes the Implement ECM is the only control that activated a diagnostic code for communication with the Engine ECM. If multiple diagnostic codes are active for communication with the Engine ECM, check for problems in the connectors or problems near the Engine ECM. The problem may be with the Engine ECM.Test Step 1. Verify the hardware and the software part numbers
Verify that the following information is correct:
The part number of the software for the Power Train ECM
The part number of the software for the Engine ECM
The part number of the Power Train ECM
The part number of the Engine ECMExpected Result:All of the part numbers are correct.Results:
YES - All of the part numbers are correct. Proceed to Test Step 2.
NO - All part numbers are NOT correct. The part number for an ECM may be incorrect. The incorrect configuration software may be installed. Repair: Replace the incorrect ECM with an ECM that has the correct part number. Flash the correct configuration software. Refer to Troubleshooting, "Electronic Control Module (ECM) - Flash Program".STOPTest Step 2. Inspect the harness connections
Turn the key start switch and the disconnect switch to the OFF position.
Inspect all harness connections that are related to the Cat Data Link. Make sure that the connectors are clean and tight. Note: Refer to Troubleshooting, "Electrical Connecter - Inspect" for more information.Expected Result:The machine harness connectors are tight and free of corrosion.Results:
YES - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 3.
NO - The machine harness connectors are in need of repair.Repair: Repair the machine harness or replace the machine harness.STOPTest Step 3. Check for shorts to ground
The disconnect switch remains in the OFF position.
Disconnect the machine harness from all electronic control modules that use the Cat Data Link.
At the machine harness for the Power Train ECM, measure the resistance between frame ground and connector contacts J1-10 wire (893-GN(Green)) and J1-20 wire (892-BR(Brown)). Expected Result:The resistance is greater than 5000 ohms.Results:
YES - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to Test Step 4.
NO - The resistance is less than 5000 ohms. The machine harness has failed.Repair: There is a short between frame ground and the Cat Data Link circuit in the machine harness. Repair the machine harness or replace the machine harness.STOPTest Step 4. Check for a short to