ENGINE AR 1668587 - Caterpillar

Illustration 1 g01183957
Schematic of the pressure sensor
This diagnostic code is associated with the pressure sensor that is located at the rod end of the lift cylinder. The FMI 03 means that the electronic control module (ECM) has determined that the voltage of the circuit for the sensor is above normal. The pressure sensors are pulse width modulated (PWM) type sensors. The PWM signal is dependent on the input pressure. The PWM signal will vary between 200 Hz and 1600 Hz.The possible causes of this diagnostic code are listed below:
The signal circuit for the sensor is open.
The signal circuit for the sensor is shorted to the +battery circuit.
The sensor has failed.
The power circuit or the ground circuit has failed.
The ECM has 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 0769 FMI 03 is active before performing this procedure.Note: Use a calibrated digital multimeter for the measurements in this procedure.Test Step 1. CHECK FOR POWER AT THE SENSOR.
Do not disconnect the harness connector from the sensor.
Turn the key start switch and the disconnect switch to the ON position.
At the back of the harness connector for the sensor, insert a multimeter probe along the voltage supply wire (contact A).
Measure the voltage from contact A to frame ground. Expected Result:The voltage is 24 DCV.Results:
OK - The voltage is 24 DCV. Proceed to Test Step 2.
NOT OK - The voltage is not 24 DCV. The + battery circuit in the machine harness has failed.Repair: Replace the machine harness or repair the machine harness.STOPTest Step 2. CHECK FOR PROPER GROUND AT THE SENSOR.
The machine harness remains connected to the sensor.
Turn the key start switch and the disconnect switch to the OFF position.
Remove the multimeter probe from the voltage supply wire (contact A).
At the back of the harness connector for the sensor, insert a multimeter probe along the ground wire (contact B).
Measure the resistance from contact B to frame ground. Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. The ground circuit is correct. Proceed to Test Step 3.
NOT OK - The