COVER 4644976 - Caterpillar

Illustration 1 g01321483
Schematic of the Air Temperature Control PanelThis diagnostic code is associated with the air temperature control panel. The FMI 03 means that the ECM has determined that the voltage of the circuit is above normal. The possible causes of this diagnostic code are listed below:
The signal circuit is open.
The signal circuit is shorted to the +battery circuit.
The control has failed.
The power circuit or the signal return circuit has failed.
The ECM has failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 2661 FMI 03 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.System Response:A level 1 warning will be generated.Test Step 1. CHECK FOR POWER AT THE CONTROL.
Do not disconnect the harness connector from the control panel.
Turn the key start switch and the disconnect switch to the ON position.
At the back of the harness connector for the control panel, insert a multimeter probe along the voltage supply wire (contact 1).
Measure the voltage from contact 1 to frame ground.Expected Result:The voltage is 24 DCV.Results:
OK - The voltage is 24 DCV. Proceed to Test Step 2.
NOT OK - The voltage is not 24 DCV. The power supply circuit of the control panel in the machine harness has failed.Repair: Check the fuse for the control panel. Replace the machine harness or repair the machine harness.STOPTest Step 2. CHECK THE RETURN CIRCUIT OF THE CONTROL PANEL.
Disconnect the machine harness for the ECM at the J1 connector.
Turn the key start switch and the disconnect switch to the OFF position.
Remove the multimeter probe from the voltage supply wire (contact 1).
At the back of the harness connector for the control panel, insert a jumper wire at the signal return (wire J764-BR) (contact 10) long enough to reach to the ECM.
Measure the resistance from contact J1-56 to the end of the jumper wire (connected to contact 10) .Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than