BUSHING 3976730 - Caterpillar

Illustration 1 g03850040
Schematic of the transmission oil pressure sensorThis diagnostic code is related to the transmission oil pressure sensor. An FMI 04 means the Transmission ECM has determined the voltage of the sensor output signal is below normal. The sensor output is a Pulse Width Modulated (PWM) frequency signal at 500Hz ( 100Hz). The signal duty cycle changes as the sensor pressure changes.Possible causes for this diagnostic code are:
The sensor has failed.
The sensor output signal is shorted to ground.
The transmission ECM has failed, but is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes now, but clear those codes after the original diagnostic code has been corrected. Note: Poor connections are often the cause of a problem in electrical circuits. Before performing this procedure, inspect all of the harness connectors involved in the circuit. Verify that all of the connections in the circuit are clean, secure, and in good condition. If a problem is found with any of the connections: correct the problem and verify that diagnostic code CID 0127 FMI 04 is still active, before performing the following procedures. Test Step 1. CHECK THE SENSOR, THE ECM, AND THE CIRCUIT CONNECTIONS IN THE MACHINE HARNESS
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector from the Transmission Oil Pressure sensor.
Turn the key start switch and the disconnect switch to the ON position. Do not start the engine.
Observe the status of the diagnostic code. Expected Result:The CID 0127 FMI 04 diagnostic code does not change, and remains active. Results:
YES - The CID 0127 FMI 03 diagnostic code does not change, and remains active. The sensor is NOT the cause of the problem. Repair: The machine harness has failed, or the Transmission ECM may have failed. Go to Test Step 2.
NO - The CID 0127 FMI 04 diagnostic code is no longer active, and has been replaced by an active CID 0127 FMI 03 diagnostic code. The ECM has detected a valid diagnostic code.Repair: The ECM, and the harness, are correct. The sensor has failed. Replace the sensor. Go to Test Step 3. Test Step 2. CHECK THE SENSOR OUTPUT SIGNAL FOR A SHORT TO GROUND.
Turn the disconnect switch and the key start switch to the OFF position.
The harness connector remains disconnected from the transmission oil pressure sensor.
At the transmission ECM, disconnect the J1 and J2 machine harness connectors from the ECM.
Measure the resistance from J2-24 (N796-BR) to all sources of ground, on both the J1 and J2 ECM connectors.Expected Result:Each measurement is more than 5000 ohms.Results:
YES - Each measurement is more than 5000 ohms. The sensor output signal circuit is not shorted to ground. Go to Test Step 3.
NO - One of the measurements is not more than 5000 ohms. There is a short in the harness. The short is between the sensor output signal wire (N796-BR) and the wire with the low resistance. Repair, or replace, the harness. Go to Test Step 3. Test Step