DAMPER ASSEM. 2P3787 - Caterpillar

Possible causes for an FMI 3 diagnostic code are:
The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine harness is shorted to another circuit.
The signal circuit in the machine harness is open or the sensor is disconnected.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely.Possible causes for an FMI 4 diagnostic code are:
The signal circuit in the machine harness is shorted to ground.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely.
Illustration 2 g03841730
Schematic of the Implement ECM Sensor Supply
Note: The diagram above is a simplified schematic of the Implement ECM and the Sensor Supply connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision for the complete schematic.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure.
Table 3
Troubleshooting Test Steps Values Results
1. Identify The Active FMI Code Associated With The Sensor Supply Circuit Code present FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Supply Voltage
A. Turn the key start switch and the disconnect switch OFF.
B. At the harness connector, insert the positive multimeter probe along the supply positive contact. Insert the negative multimeter probe along the supply return contact.
C. Turn the key start switch and the disconnect switch ON.
D. Observe the voltage measurement.
The voltage measurement is in the range of 8.0 0.5 VDC. OK - The voltage measurement is in the range of 8.0 0.5 VDC.
Proceed to Test Step 9.
NOT OK - The voltage measurement is greater than 8.0 0.5 VDC. The power supply voltage is above normal.
Proceed to Test Step 3.
3. Check The ECM Power Supply At The ECM With The Circuit Disconnected
A. Turn the key start switch and the disconnect switch OFF.
B. At the ECM harness connector, remove the power supply positive circuit from the connector body.
C. Turn the key start switch and the disconnect switch ON.
D. At the connector, measure the supply voltage with the circuits disconnected. Insert the multimeter probes at the positive contact and at the return contact.
E. Measure the voltage.
The voltage measurement is in the range of 8.0 0.5 VDC. OK - The voltage measurement is in the range of 8.0 0.5 VDC. The voltage is correct.
Proceed to Test Step 4.
NOT OK - The voltage measurement is greater than 8.0 0.5 VDC.
Proceed to Test Step 9.
4. Check For A Short
A. Turn the key start switch and the disconnect switch OFF.
B. Disconnect the harness connector from the sensor and ECM.
C. At the harness connector for