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| Illustration 1 | g01447437 |
Connections of the 8 volt supply | |
This diagnostic code is recorded when the Transmission ECM reads the voltage of the sensor supply circuit as higher than normal.
Possible causes of this diagnostic code are listed:
- The power supply circuit is shorted to a higher voltage source.
- 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 the diagnostic codes when the problem has been corrected. Verify that the CID 0041 FMI 03 is active before performing this procedure.
Use a digital multimeter for the measurements in this procedure.
System Response:
All of the sensors that receive power from the 8 volt supply are disabled.
Test Step 1. CHECK FOR THE CORRECT VOLTAGE AT THE ECM.
- Turn the disconnect switch and the key start switch to the ON position.
- Check the voltage at the ECM connector from contact J1-44 (sensor supply) to contact J1-45 (ground). Use the multimeter probes to measure the voltage. Do NOT disconnect the machine harness from the ECM.
Expected Result:
The voltage is 8.0 ± 0.5 DCV.
Results:
- OK - The voltage is 8.0 or ± 0.5 DCV. The sensor supply voltage is correct. Verify that the diagnostic code is present. If the diagnostic code is still present, the ECM has failed. Replace the ECM.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code is active. Prior to replacing and ECM, contact your dealership for possible consultation with Caterpillar. If the ECM requires replacing, see Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NOT OK - Voltage is greater than 8.0 ± 0.5 DCV. The sensor supply voltage is NOT correct. Proceed to test step 2.
Test Step 2. CHECK THE HARNESS FOR A SHORT TO THE +BATTERY CIRCUIT.
- The disconnect switch and the key start switch remain in the ON position.
- Disconnect the machine harness from the ECM.
- At the machine harness connector for the ECM, measure the voltage from connector contact J1-44 (sensor supply) to contact J1-45 (ground).
Expected Result:
The voltage is 0.0 ± 0.5 DCV.
Results:
- OK - The voltage is 0.0 ± 0.5 DCV. The voltage is correct. The ECM has failed.
Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code is active. Prior to replacing and ECM, contact your dealership for possible consultation with Caterpillar. If the ECM requires replacing, see Troubleshooting, "Electronic Control Module (ECM) - Replace".
STOP
- NOT OK - Voltage is NOT 0.0 ± 0.5 DCV. The harness has failed.
Repair: The machine harness is shorted to the +battery circuit. Repair the machine harness or replace the machine harness.
STOP