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| Illustration 1 | g01273295 |
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Connections of the Cat Data Link | |
This diagnostic code is recorded when the Chassis ECM does not receive expected information from the key reader over the data link.
Test Step 1. CHECK THE CAT ET SCREEN.
- Check the Cat ET screen for a communication error between the Chassis ECM and the key reader.
Note: The diagnostic code for the key reader is CID 1960 FMI 09.
Expected Result:
The Cat ET reports a diagnostic code of CID 1960 FMI 09 as being active.
Results:
- YES - The Cat ET reports a diagnostic code of CID 1960 FMI 09 as being active.
Repair: Troubleshoot the connections for the Cat Data Link between the key reader and the Chassis ECM.
Proceed to Test Step 3.
- NO - The diagnostic code has NOT been logged or the diagnostic is NOT active. Proceed to Test Step 2.
Test Step 2. CHECK FOR POWER TO THE KEY READER.
- With the keyswitch in the ON position, check for system voltage between contact 3 and contact 4 of the key reader.
Expected Result:
The voltage that is measured is approximately system voltage.
Results:
- YES - The voltage that is measured is approximately system voltage. The voltage is correct. Proceed to Test Step 4.
- NO - System voltage is NOT present. The wiring harness has failed.
Repair: Check the wiring harness for signs of damage. Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK THE WIRING HARNESS OF THE CAT DATA LINK FOR AN OPEN CIRCUIT.
- Disconnect the J1 harness connector from the Chassis ECM.
- On the side of the harness for the key reader, install a jumper wire between contact 3 and contact 4.
- At the J1 harness connector for Chassis ECM, measure the resistance between J1-10 and J1-20 of the connector for the Chassis ECM.
Expected Result:
The resistance is less than 5 ohms.
Results:
- YES - The resistance is less than 5 ohms between pin 3 and pin 4. The wiring is correct. Proceed to Test Step 4.
- NO - The resistance is greater than 5000 ohms between pin 3 and pin 4. The wiring for the Cat Data Link is not correct between the ECM and the key reader.
Repair: Check the wiring harness for signs of damage. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK THE WIRING HARNESS OF THE CAT DATA LINK FOR A SHORT TO GROUND.
- The connector for the key reader and the Chassis ECM remain disconnected.
- The jumper wire remains installed.
- Measure the resistance between connector contact J1-10 of the Chassis ECM and frame ground.
- Measure the resistance between connector contact J1-20 of the Chassis ECM and frame ground.
Expected Result:
The resistance is greater than 5000 ohms.
Results:
- YES - The resistance is greater than 5000 ohms. The resistance is correct. Proceed to Test Step 5.
- NO - The resistance is less than 5 ohms. The wiring harness is shorted to the ground.
Repair: Check the wiring harness for signs of damage. Repair the machine harness or replace the machine harness.
STOP
Test Step 5. CHECK THE WIRING HARNESS OF THE CAT DATA LINK FOR A SHORT TO + BATTERY.
- The connector for the key reader and the Chassis ECM remain disconnected.
- The jumper wire remains installed.
- Measure the resistance between the connector contact J1-10 of the Chassis ECM and +battery.
- Measure the resistance between the connector contact J1-20 of the Chassis ECM and +battery .
Results:
- YES - The resistance is greater than 5000 ohms. The resistance is correct. Proceed to Test Step 6.
- NO - The resistance is less than 5 ohms. The wiring harness is shorted to the + battery circuit.
Repair: Check the wiring harness for signs of damage. Repair the machine harness or replace the machine harness.
STOP
Test Step 6. CHECK THE TERMINATION RESISTORS FOR THE CAT DATA LINK FOR AN OPEN CIRCUIT.
- Locate the plugs for the termination resistors for the Cat Data Link, located near the key reader and the Chassis ECM. Remove the plugs for the termination resistors. Measure the resistance between pin A and pin B on both plugs.
Expected Result:
The resistance of each plug is approximately 120 ohms.
Results:
- YES - The resistance is approximately 120 ohms. The resistance is correct. Reinstall the plugs for the termination resistors.
Repair: The key reader or the Chassis ECM has failed. A failure of the key reader or the Chassis ECM is unlikely. Perform the previous Test Steps again. If the cause of the problem is not found, replace the key reader and test again. If the cause of the problem is not found, replace the Chassis ECM.
Check the circuit again. Use the Cat ET service tool in order to test the wiring harness of the machine. Manipulate the wires and monitor the output of Cat ET for changes. This test can detect intermittent short circuits and momentary open circuits in the machine wiring harness.
A failure of the ECM is unlikely. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. Refer to the Testing and Adjusting, "Electronic Control Module (ECM) - Replace" procedure in the service manual for your machine.
STOP
- NO - The resistance is greater than 120 ohms. The termination resistors have failed.
Repair: Replace the termination resistor.
STOP