BLOCK 6G4828 - Caterpillar

Illustration 1 g03815785
Connections of the Cab Air Temperature ControlThis diagnostic code is recorded when the Implement ECM reads the input signal from the Cab Air Temperature Control and the voltage is above normal.If the voltage of the sensor input circuit is greater than 4.98 VDC, an FMI 3 diagnostic code will be activated.Possible causes of the diagnostic code are listed:
There is an open in the signal circuit.
The signal circuit is shorted to another voltage source.
The HVAC panel has failed.
The ECM has failed. This condition is unlikely.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit.
Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition.
If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.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.System Response:
The Auto Temperature Control feature will not work properly.Test Step 1. CHECK THE SENSOR CIRCUIT FOR AN OPEN CIRCUIT
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector from the panel.
At the machine harness connector for the HVAC panel, connect a jumper wire from the signal contact 5 (wire A524-BR) to frame ground.
Turn the key start switch and the disconnect switch to the ON position.
Observe the status of the active CID 2661 FMI 03 diagnostic code.Expected Result:The active CID 2661 FMI 03 diagnostic code is no longer active. A CID 2661 FMI 04 diagnostic code becomes active when the signal wire is grounded.Results:
YES - The active CID 2661 FMI 03 diagnostic code is no longer active. A CID 2661 FMI 04 diagnostic code has been activated after the signal wire is grounded. Proceed to Test Step 2.
NO - The CID 2661 FMI 03 diagnostic code remains active. The status of the active diagnostic code does not change when the signal wire is grounded. There is an open or a poor connection in the signal wire.Repair: Check the signal circuit for an open or for a poor connection. Repair or replace the machine harness.STOPTest Step 2. CHECK THE SENSOR CIRCUIT FOR A SHORTThe machine harness connector remains disconnected from the panel. The key start switch and the disconnect switch remain in the OFF position.
Remove the jumper wire that was installed in the previous step.
Disconnect the machine harness connector J1 from the ECM.
At the machine harness connector for the ECM, measure the resistance from the signal contact J1-44 (wire A524-BR) to all of the other contacts that are used in the machine harness connectors of the ECM.Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more