SEAL-U-CUP 2508708 - Caterpillar

Illustration 1 g03202718
Cab ventilation duct (Louver) temperature sensor schematic The CID 2663 diagnostic code is associated with the cab ventilation duct temperature sensor. An FMI 03 diagnostic code is recorded when the Implement ECM finds the sensor signal voltage is above normal.Possible causes of the diagnostic codeare listed:
Failed sensor.
Open signal circuit or disconnected sensor.
Open circuit return.
Signal circuit shorted to +battery.
Failed ECM, but highly unlikely.Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean. Verify that all connections in the circuit are secure. Verify that all connections in the circuit 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.System Response:A level 1 warning will be generated.Note: Ensure that CID 2663 FMI 03 is active. This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.Test Step 1. CHECK FOR AN OPEN IN THE RETURN CIRCUIT.
Turn the key start switch and the disconnect switch to the OFF position.
The sensor remains disconnected from the machine harness.
Disconnect the machine harness connector J1 from the ECM.
At the J1 machine harness connector for the ECM, place a jumper wire from T993-BR to ground.
At the machine harness connector for the sensor, measure the resistance from contact 1 (wire T993-BR) to ground.Expected Result:The resistance measurement should measure less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The harness is correct.Repair: The ECM may have failed. Recheck the status of the diagnostic code. If the diagnostic code remains present, exit this procedure and perform this procedure again. If the cause of the problem is not found, contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, see Troubleshooting, "Electronic Control Module (ECM) - Replace".STOP
NOT OK - The resistance that is measured is not correct.Repair: There is an open in the machine harness. The open is in the return circuit with the high resistance measurement. Repair the harness or replace the harness.STOPTest Step 2. CHECK FOR AN OPEN IN THE SIGNAL CIRCUIT.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the J1 and J2 machine harness connector from the ECM.
At the machine harness connector for the sensor, install a jumper wire from contact 1 (wire T993-BR) to contact 2 (wire E558-YL).
At the machine harness connector J1, measure the resistance from contact J1-30 (wire E558-YL) to Frame Ground.Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measures less than 5 ohms. Proceed to 3.
NOT OK - The resistance measurement is greater than 5 ohms. There is an open in the signal circuit.Repair: Repair the harness or replace the harness.STOPTest Step 3. CHECK THE SIGNAL CIRCUIT FOR A SHORT.
The disconnect switch and the key start switch remain in the OFF position.
The