COOLER AS-OIL 2877424 - Caterpillar

Illustration 1 g01081042
Schematic of the Auto Select SwitchThis diagnostic code is associated with the auto select switch. The switch is connected to two inputs of the ECM. One contact is open and the other contact is grounded during proper operation.This FMI 03 means that the ECM has determined that the normally open contact and the normally closed contact are open.Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 874 FMI 03 is active before performing this procedure.System Response:When this diagnostic code is active the hydraulic control system will default to the "Service Mode" state.Test Step 1. CHECK THE GROUND CIRCUIT OF THE SWITCH IN THE HARNESS.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector(s) from the ECM.
Measure the resistance between contact "J1-45" (wire J766-BR) of the machine harness for the ECM and the contact "J1-33" (wire Y930-BU) .Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. The circuit is correct. Proceed to Test Step 2.
NOT OK - The resistance is greater than 5000 ohms. The circuit is open. The machine harness has failed.Repair: Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE SWITCH CIRCUITS FOR A SHORT TO THE +BATTERY CIRCUIT.
The machine harness connector(s) remains disconnected from the ECM.
The disconnect switch and the key start switch remain in the OFF position.
Disconnect the harness connector to the switch.
At the machine harness connector for the ECM, measure the resistance from contact "J1-33" (wire Y930-BU) and contact "J1-32" (wire Y929-GN) of the machine harness to all the contacts that are used in the machine harness connectors for the ECM.Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The harness is correct. Proceed to Test Step 3.
NO - One or more of the measurements were less than 5 ohms. There is a short in the machine harness. Repair: The short is between wire Y930-BU and the circuit with the lowest resistance measurement or the short is between wire Y929-GN and the circuit with the lowest resistance measurement. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK THE SWITCH CIRCUITS IN THE HARNESS.
The machine harness remains disconnected from the ECM and the switch.
At the harness connector for the switch, connect a jumper wire between contact "6" (wire Y929-GN) and contact "7" (wire Y930-BU).
At the harness connector for the ECM, measure the resistance from contact "J1-32" (wire Y929-GN) to contact "J1-33" (wire Y930-BU).Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 4.
NOT OK - The resistance is greater than 5000 ohms. The circuit is open.Repair: The machine harness has failed. Repair the machine harness or replace the machine harness.STOPTest Step 4. CHECK THE OPERATION OF THE SWITCH.
Remove the