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| Illustration 1 | g01447903 |
Connections of the hydraulic oil temperature sender | |
This diagnostic code is recorded when the ECM reads the signal voltage of the hydraulic oil temperature sender and the voltage is too high. The possible causes of this diagnostic code are listed here:
- The sender has failed.
- The return circuit of the sender is open in the machine harness.
- The signal circuit in the machine harness is shorted to a source of positive voltage.
- The signal circuit in the machine harness is open or the sender is disconnected.
- The ECM has failed. This is unlikely.
Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all of the connections in the circuit are clean and secure. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.
Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code CID 0600 FMI 03 is active before performing this procedure.
Note: Use a digital multimeter for the measurements in this procedure.
Test Step 1. CHECK THE CONTROL AND THE HARNESS.
- Turn the disconnect switch and the key start switch to the ON position.
- Disconnect the machine harness connector from the temperature sender (hydraulic oil).
- At the machine harness connector for the sender, measure the voltage (DCV) between the signal contact 1 (wire R732-BR) and the return contact 2 (wire J764-BR).
Expected Result:
The voltage is between 4.5 and 8.0 DCV.
Results:
- OK - The voltage is between 4.5 and 8.0 DCV. The ECM and the harness are correct.
Repair: Replace the sender.
STOP
- NOT OK - The voltage is not between 4.5 and 8.0 DCV. The ECM may have failed or the harness has failed. Proceed to Test Step 2.
Test Step 2. CHECK THE RETURN CIRCUIT OF THE HARNESS.
- The sender remains disconnected.
- Turn the disconnect switch and the key start switch to the OFF position.
- Disconnect the J1 and J2 machine harness connectors from the ECM.
- Measure the resistance of the return circuit between contact 2 (wire J764-BR) of the machine harness for the sender and contact J1-45 of the machine harness for the ECM.
Expected Result:
The resistance is less than 5.0 ohms.
Results:
- OK - The resistance is less than 5.0 ohms. The harness resistance is correct. Proceed to Test Step 3.
- NOT OK - The resistance is greater than 5.0 ohms. The ground circuit in the harness has failed. There is an open circuit between the ground contact and frame ground.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK FOR A SHORTED HARNESS
- The sender and the ECM remain disconnected from the machine harness.
- The disconnect switch and the key start switch remain in the OFF position.
- At the machine harness connector for the sender, measure the resistance between the signal contact 1 (wire R732-BR) and all contacts that are used in the machine harness connector for the ECM.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The ECM has failed.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Prior to replacing an ECM, always contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness. The short is between the signal contact J1-30 (wire R732-BR) and the circuit with the low resistance measurement.
Repair: Repair the machine harness or replace the machine harness.
STOP