TIRE 9R2939 - Caterpillar

Illustration 1 g02760221
Connections for the 583T and PL83 8 VDC power supply
Illustration 2 g02760476
Connections for the 587T and 572RII, and PL87 8 VDC power supplyThis diagnostic code is recorded when the ECM reads the voltage of the sensor supply circuit (wire C985-BU) as higher than normal. The following causes could trigger this diagnostic code:
The sensor supply circuit (wire C985-BU) is shorted to the +battery circuit.
A sensor has failed.
The power train ECM has failed. An ECM failure is unlikely.Note: Ensure that the CID 0041 FMI 03 is active.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 connector of the ECM from contact J1-44 (sensor supply) to contact J1-45 (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 VDC.Results:
OK - Voltage is 8.0 0.5 VDC. 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: An ECM failure is unlikely. 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 Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP
NOT OK - Voltage is greater than 8.0 0.5 VDC. 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 J1 and J2 machine harnesses from the ECM.
At the machine harness connector for the ECM, measure the voltage from connector contact J1-44 (sensor supply) to contact J1-45 (return).Expected Result:The voltage is 0.0 0.5 VDC.Results:
OK - The voltage is 0.0 0.5 VDC. The voltage is correct. The ECM has failed.Repair: An ECM failure is unlikely. 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 Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP
NOT OK - Voltage is NOT 0.0 0.5 VDC. The harness has failed.Repair: The machine harness is shorted to the +battery circuit. Repair the machine harness or replace the machine harness.STOP