ACCESSORY GP-CAB 2115261 - Caterpillar

Illustration 1 g01002521
Schematic of the transmission oil pressure sensorThis diagnostic code is associated with the pressure sensor (transmission oil). The FMI 03 means that the ECM has determined that the signal wire (X730-BR) of the pressure sensor as being shorted to +battery. The pressure sensor is a component that produces a PWM output.The output frequency of the sensor is approximately 5000 Hz. The duty cycle of the signal varies as the pressure sensor moves.The possible causes of this diagnostic code are listed below:
A shorted harness.
A failed sensor.
An open circuit.
The ECM may have failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0127 FMI 03 is active before performing this procedure.System Response:The oil pressure for the transmission is unknown. The ECM will force the parking brake to the ENGAGED position. The parking brake will operate properly when the diagnostic code is corrected.Test Step 1. CHECK THE SIGNAL CIRCUIT
Disconnect the machine harness from the sensor.
Turn the disconnect switch and the key switch to the ON position.
At the machine harness connector for the sensor, measure the voltage (DCV) between signal contact C (wire X730-BR) and return contact B (wire 202-BK). Expected Result:The voltage is approximately 7 DCV.Results:
YES - The voltage is approximately 7 DCV. The ECM and the harness for the ECM are correct.Repair: The sensor and/or the harness for the sensor are faulty. Check the harness of the sensor. If no defect is found in the sensor harness, replace the sensor. Stop.
NO - The voltage is NOT approximately 7 DCV. The ECM may be faulty or the harness is faulty. Proceed to Test Step 2.Test Step 2. CHECK THE RETURN CIRCUIT OF THE HARNESS
The sensor remains disconnected.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connectors from the ECM.
At the machine harness connector for the sensor, measure the resistance. Measure the resistance between contact B (wire 202-BK) and frame ground.Expected Result:The resistance is less than 5 ohms.Results:
YES - The resistance is less than 5 ohms. The harness resistance is correct. Proceed to Test Step 3.
NO - The resistance is 5 ohms or greater. The return circuit in the harness is faulty.Repair: There is an open circuit between the return contact B (wire 202-BK) and the return circuit.