PISTON 2128485 - Caterpillar

Illustration 1 g01384614
Schematic for Sensor Supply VoltageThis diagnostic code is recorded when the ECM reads the voltage of a 8 DCV sensor supply circuit as higher than normal. Possible causes of this diagnostic code are listed:
The output of sensor supply has shorted to + battery.
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 FOR THE CORRECT 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 greater than 8.0 DCV. The sensor supply voltage is NOT correct. Proceed to test step 2.Test Step 2. CHECK THE HARNESS FOR A SHORT TO THE +BATTERY CIRCUIT
The disconnect switch and the key start switch remain in the ON position.
Disconnect the machine harness from the ECM.
At the machine harness connector for the ECM, measure the voltage from connector contact J2-12 (wire C985-BU) to contact J1-16 (wire 202-BK).Expected Result:The voltage is 0.0 0.5 DCV.Results:
OK - The voltage is 0.0 0.5 DCV. The voltage 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 - Voltage is NOT 0.0 0.5 DCV. The harness has failed.Repair: The machine harness is shorted to the +battery circuit. Repair the machine harness or replace the machine harness.STOP