RELAY 2872809 - Caterpillar

Illustration 1 g01217611
Schematic of the +8 Volt Sensor Supply
This diagnostic code is recorded when the Power Train electronic control module (ECM) reads the voltage of the sensor supply circuit as higher than normal. Possible causes of this diagnostic code are listed:
The output of sensor supply to battery has shorted.
The impeller clutch pressure sensor is faulty or the torque converter oil temperature sensor is faulty.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 (sensor supply) to contact J1-16 (ground). 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 or the voltage is 10.0 0.5 DCV.Results:
OK - The voltage is 8.0 or 0.5 DCV or the voltage is 10.0 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. Replace the ECM.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 or 10.0 0.5 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 (sensor supply) to contact J1-16 (ground). 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