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| Illustration 1 | g02730584 |
8 V Power Supply connections | |
The 8V power supply provides power for the all 8V sensors.
The CID 0041 FMI 03 service code is activated when the ECM detects that the voltage of the 8 V power supply circuit is higher than normal.
The following causes could signal this diagnostic code:
- The sensor supply circuit is shorted to a higher voltage source.
- The ECM has failed. This is unlikely.
Note: Ensure that the CID 0041 FMI 03 is active before performing this procedure.
System Response:
A level 2 warning is generated. Unexpected Motor Speed Detection will be disabled. While the machine is NOT in neutral, a level 3 warning will indicate Unexpected Motor Speed Detection Disabled. Since the throttle position sensor will be disabled, Underspeed control will be disabled. The Auxiliary Circuit will be disabled (if thumbroller is installed).
Test Step 1. CHECK THE VOLTAGE AT THE SENSOR
- Turn the key start switch to the ON position.
- Disconnect the machine harness connector from one of the sensors.
- At the machine harness connector for the sensor, measure the voltage from connector contact 1 (wire P769-YL) to connector contact 2 (wire P770-WH).
Expected Result:
The voltage measurement is 8.0 ± 0.5 DCV.
Results:
- OK - The voltage measurement is 8.0 ± 0.5 DCV. The voltage is correct. Proceed to Test Step 4.
- NOT OK - The voltage measurement is greater than 8.0 ± 0.5 DCV. The measurement is not correct. Proceed to Test Step 2.
Test Step 2. CHECK THE POWER SUPPLY AT THE ECM
- Turn the key start switch to the OFF position.
- At ECM connector J1, use a 151-6320 Removal Tool to remove the supply wire and socket at contact J1-44 (wire P769-YL) and the return wire and socket at contact J1-45 (wire P770-WH) from the connector. The harness connector J1 remains connected to the ECM.
- Turn the key start switch to the ON position.
- At ECM connector J1, measure the voltage at the ECM pins between the power supply contacts J1-44 and J1-45.
Expected Result:
The voltage measurement is 8.0 ± 0.5 DCV.
Results:
- OK - The voltage measurement is 8.0 ± 0.5 DCV. The voltage is correct. The ECM power supply is correct. Install the wires and sockets that were removed from the J1 connector back to their original locations. Proceed to Test Step 3.
- NOT OK - The voltage measurement is greater than 8.0 ± 0.5 DCV. The ECM power supply is not correct.
Repair: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
STOP
Test Step 3. CHECK THE HARNESS FOR A SHORT TO THE +BATTERY CIRCUIT
The machine harness connector remains disconnected from the sensor.
- Turn the key start switch to the OFF position.
- Disconnect the negative battery cable.
- Disconnect the machine harness connectors from the ECM.
- At the harness connector J1, check the resistance from contact J1-44 (wire P769-YL) to all of the other ECM +battery contacts that are connected to the ECM. The +battery contacts are J1-31, J1-38, J1-39, J1-46 and J1-47.
- At the harness connector J1, check the resistance from contact J1-44 (wire P769-YL) to all of the other ECM contacts that are used in connectors J1 and J2.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each resistance measurement is greater than 5000 ohms. The supply circuit is not shorted to another circuit. Proceed to Test Step 4.
- NOT OK - One or more of the resistance measurements is less than 5000 ohms. There is a short in the machine harness.
Repair: The power supply circuit is shorted to a voltage source in the machine harness. Refer to the complete machine Electrical System Schematic. Examine the supply circuit in order to determine where the problem could be. Repair the machine harness or replace the machine harness.
STOP
Test Step 4. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, corrosion, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
- Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are fastened.
- Turn the key start switch to the ON position.
- Operate the machine.
- Determine if the CID 0041 FMI 03 diagnostic code is active.
Expected Result:
The CID 0041 FMI 03 diagnostic code is active.
Results:
- YES - The CID 0041 FMI 03 diagnostic code is active. The problem has not been corrected.
Repair: Check the circuit again. If the cause of the problem is not found, contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, see Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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- NO - The CID 0041 FMI 03 diagnostic code is not active. The problem does not exist at this time.
Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.
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