RING-BACKUP 3563310 - Caterpillar

Illustration 1 g02260774
Schematic for the Cab AC Temperature sensor
This diagnostic code is associated with the Cab AC Temperature sensor. An FMI 03 means the Brake ECM has determined the voltage level of the sensor (wire C552-WH(White)) is above normal.Possible causes of the diagnostic code are:
The sensor has failed.
The sensor circuit is open, or the sensor is disconnected.
The signal circuit is shorted to the +battery.
The Brake ECM may have failed, but 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, 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.System Response:A level 1 warning will be generated.Note: Ensure that the CID 0779 FMI 03 diagnostic code 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 THE SENSOR.
Table 1
CELSIUS TEMPERATURE FAHRENHEIT TEMPERATURE RESISTANCE
10 50 1991.4
15 59 1571.9
20 68 1249.5
25 77 1000
30 86 805.5 Note: The Cab AC Temperature sensor resistance is inversely proportional to measured temperature. Typical values range from about 2000 ohms at 10C°(50F°), down to 800 ohms at 30C° (86F°).
Turn the key start