CHANNEL 6D0985 - Caterpillar

Illustration 1 g01927353
Schematic of "Boom Cylinder Head Pressure" sensorThis diagnostic code is recorded when the ECM reads the voltage of the circuit of the sensor as being below normal. The signal circuit of the sensor may be shorted to ground.The possible causes of this diagnostic code are listed below:
The signal circuit for the sensor is shorted to ground.
The sensor has failed.
The ECM has failed. A failure of the Machine ECM is unlikely. Note: The Machine ECM is equipped with LED indicators that serve as a self-diagnostic check. With the key start switch ON, the following can be determined by the ECM indicator lights:
If all of the LED lights are Off, voltage is not being supplied to the Machine ECM. Check for power to the ECM.
If the yellow LED is Flashing, a communication error exists on the "CAN" data-link circuit.
If the yellow LED is constantly On, the Machine ECM software may be missing / not loaded.
If the red LED is Flashing, the Machine ECM has failed and may need replacement. 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.Note: Ensure that the diagnostic code of CID 1969 FMI 04 is active before performing this procedure. Test Step 1. CHECK THE SENSOR.
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Observe the status of the diagnostic code. Disconnect the joystick from the machine harness.Expected Result:The CID 1969 FMI 04 remains active. The FMI 04 diagnostic code has not changed and the diagnostic code is still active.Results:
OK - The diagnostic code remains active. The sensor is correct. Proceed to Test Step 2.
NOT OK - The diagnostic code is no longer active. The sensor has failed.Repair: Replace the sensor.STOPTest Step 2. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the sensor.
Disconnect machine harness connectors from the ECM.
At the machine harness connector for the ECM, measure the resistance from the signal contact J1-38 (wire H446-PK) of the machine harness to all possible sources of ground. Measure the resistance to all contacts that are used in the J1 and J2 harness connectors.Expected Result:Each resistance measurement should be greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more resistance measurements are not correct. There is a short in the machine harness. The short is between signal contact J1-38 (wire H446-PK) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Inspect the contacts of the harness connectors. Clean the contacts of the harness connectors.
Reconnect all harness connectors.
Turn the disconnect switch and the key start switch to the ON position.
Enter the service mode of the Monitoring System