NAMEPLATE 7C5253 - Caterpillar

Illustration 1 g01897718
Connections of the Cab Air Temperature Control switch
This diagnostic code is associated with the Cab Air Temperature Control switch. The FMI 04 diagnostic code means that the Brake ECM has determined that the voltage the signal circuit for the sensor is above normal.Conditions that can cause this diagnostic code to be activated are listed below:
The switch for the AC has failed.
The AC switch is shorted to the +battery circuit
The ECM has failed. This is unlikely. 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, secure and 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: Ensure that CID 2659 FMI 04 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 problem has been corrected.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE STATUS OF THE DIAGNOSTIC CODE
Inspect the harness connectors. Clean the contacts for the harness connectors. Check all wires for damage from chafing, corrosion, or excessive heat.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.
Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are completely fastened.
Turn the disconnect switch and the key start switch to the ON position.
Operate the machine.
Determine if the CID 2659 FMI 04 diagnostic code is active. Expected Result:The CID 2659 FMI 04 diagnostic code is active.Results:
YES - The CID 2659 FMI 04 diagnostic code is active. The diagnostic code has not been corrected. Proceed to Test Step 2.
NO - The CID 2659 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation.STOPTest Step 2. CHECK THE SWITCH OPERATION
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the switch from the machine harness.
Connect one lead of the multimeter to Contact 1 (C540-GY(Grey)) of the switch.
Connect the other lead of the multimeter to Contact 2 (C567-WH(White)) of the switch.
Operate the switch while checking for continuity from Contact 1 to Contact 2 of the switch.
Move the multimeter lead from Contact 1 to Contact 3.
Operate the switch while checking for continuity from Contact 3 to Contact 2 of the switch. Expected Result:Continuity exists from Contact1 to Contact 2 only when the switch is in the ON