ELBOW AS 1287901 - Caterpillar

Illustration 1 g01384614
Schematic for Sensor Supply VoltageThe diagnostic code is recorded when the ECM indicates that the voltage of the 8 VDC sensor supply circuit is too low. Possible causes of this diagnostic code are listed:
The output of sensor supply has an open circuit.
A sensor has failed.
The ECM has failed. This is unlikely.System Response:The machine response is listed:
The lockup clutch is disabled.
Hesitation during direction shifts.
Calibrations will not function.Test Step 1. CHECK THE VOLTAGE AT THE ECM.
Turn the disconnect switch and the key start switch to the ON position.
Check the voltage at the ECM connector from contact J2-12 (wire C985-BU) to contact J1-16 (wire 202-BK). Use the 7X-1710 Cable probes to measure the voltage. Do NOT disconnect the machine harness from the ECM. Expected Result:The voltage is 8.0 0.5 DCV.Results:
OK - The voltage is 8.0 or 0.5 DCV. The sensor supply voltage is correct. Verify that the diagnostic code is present. If the diagnostic code is still present the ECM has failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code is active. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOP
NOT OK - Voltage is NOT 8.0 0.5 DCV. The voltage is less than 8.0 0.5 DCV. The sensor supply voltage is NOT correct. Proceed to test step 2.Test Step 2. CHECK FOR A SHORT TO GROUND.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the ECM.
At the harness connector for the ECM, measure the resistance between frame ground and contact J2-12 (wire C985-BU) of the sensor supply circuit. Expected Result:The resistance is greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. The ECM has failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code is active. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOP
NOT OK - The resistance is less than 5000 ohms. The machine harness or a sensor has failed. Proceed to test step 3.Test Step 3. DISCONNECT THE SENSORS.
The key start switch and the disconnect switch remain in the OFF position.
One at a time, disconnect any sensor that uses the sensor supply voltage from the machine harness.
After disconnecting the sensor(s), check the resistance from frame ground to contact J2-12 (wire C985-BU) of the machine harness connector for the ECM.Expected Result:The resistance is greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. The sensor that was just disconnected has failed.Repair: Replace the sensor.STOP
NOT OK - The resistance is less than 5000 ohms. If the resistance is less than 5000 ohms after all the sensors have been disconnected from the machine harness. The