ANGLE A 9K1477 - Caterpillar

Illustration 1 g02475852
Connections of the Cab Air Temperature Sensor
This diagnostic code is associated with the Cab Air Temperature Sensor. The FMI 03 means that the Implement ECM has determined that the sensor circuit voltage is above normal. The Relay Driver Module communicates the information for this diagnostic code via CAN Datalink to the Implement ECM.The sensor resistance range is 33,650 ohms at −40° C (−40° F) to 18.6 ohms at 150° C (302° F). The possible causes of this diagnostic code are listed below:
There is an open in the sensor circuit.
The signal circuit is shorted to another voltage source.
The sensor has failed.
The Relay Driver Module 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.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 sensor.
At the machine harness connector for the sensor, connect a jumper wire from the signal contact 1 (wire C552-WH(White)) to frame ground.
Turn the key start switch and the disconnect switch to the ON position.
Observe the status of the active CID 0779 FMI 03 diagnostic code. Expected Result:The active CID 0779 FMI 03 diagnostic code is no longer active. A CID 0779 FMI 04 diagnostic code becomes active when the signal wire is grounded.Results:
YES - The active CID 0779 FMI 03 diagnostic code is no longer active. A CID 0779 FMI 04 diagnostic code has been activated after the signal wires is grounded. Proceed to Test Step 2.
NO - The CID 0779 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 sensor. 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 Relay Driver Module.
At the machine harness connector for the Relay Driver Module, measure the resistance from the signal contact J1-30 (wire C552-WH(White)) to all of the other contacts that are used in the machine harness connectors for the Relay Driver Module. Expected Result:Each resistance measurement is greater than 5000