BODY-VALVE 9T2179 - Caterpillar

Illustration 1 g03815754
Schematic of the Cab (Recirculation Filter) Air Temperature SensorThis diagnostic code is recorded when the Implement ECM reads the input signal for the Cab Air Temperature Sensor and the voltage is below normal.If the voltage of the sensor input circuit is less than 0.05 VDC, an FMI 04 diagnostic code will be activated.The possible causes of this diagnostic code are listed below:
The signal circuit for the sensor is shorted to ground.
The sensor has failed.
The ECM has failed. The failure of ECM is 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:
The Auto Temperature Control feature will not work properly.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. Ensure that the diagnostic code of CID 779 FMI 4 is active before performing this procedure. Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Disconnect the sensor from the machine harness.
Observe the status of the diagnostic code.Expected Result:The diagnostic code remains active.Results:
OK - The diagnostic code remains active. The sensor is correct. Proceed to Test Step 2.
NOT OK - The diagnostic code changes from an FMI 04 to an FMI 03. The sensor has failed. Repair: Replace the sensor. STOPTest Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT
Turn the key start switch and the disconnect switch to the OFF position.
Locate and disconnect the sensor from the machine harness.
Disconnect the J1 and J2 machine harness connectors from the Implement ECM.
At the J1 and J2 machine harness connectors for the Implement ECM, measure the resistance from the signal contact J1-29 (wire C552-WH) to all other J1 and J2 contacts. Expected Result:Each resistance measurement should be greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The harness is not at fault. Proceed to Test Step 3.
NOT OK - One or more resistance measurements are less than 5000 ohms. There is a short in the machine harness somewhere between signal contact J1-29 (wire C552-WH) and the circuit with the low resistance measurement.Repair: Repair or replace the harness. STOPTest Step 3. CHECK THE STATUS OF THE DIAGNOSTIC CODE
Inspect the harness connectors. Clean the contacts of the harness connectors. Check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
Reconnect all harness connectors in order to