CYLINDER & MTG GP-SIDESHIFT 3801456 - Caterpillar

Illustration 1 g00676862
Schematic of the Ambient Air Temperature Sensor
This diagnostic code is recorded when the ECM reads the sensor signal and the signal is too high. The possible causes of this failure are listed below:
The sensor has failed.
The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine harness is shorted to +battery.
The signal circuit in the machine harness is open or the sensor is disconnected.
The ECM has failed.System Response:171-03 causes the ambient air temperature to constantly or intermittently indicate the maximum temperature. Note: The "Sensor Voltage Test" within the topic "Pulse Width Modulated Sensor-Test" also covers the troubleshooting of a failed sensor.Test Step 1. CHECK THE ELECTRONIC CONTROL MODULE AND THE MACHINE HARNESS.
Turn the disconnect switch and the key start switch to the "ON" position.
Disconnect the machine harness from the ambient air temperature sensor.
At the machine harness connector for the sensor, measure the voltage between the signal contact C (wire C453-YL(Yellow)) and the ground contact B (wire J842-BK(Black)). Expected Result:The voltage is 8.0 0.5 DCV. Results:
OK - The voltage is 8.0 0.5 DCV. The ECM and the machine harness are correct. Repair: The sensor has failed. Perform the Testing and Adjusting, "Pulse Width Modulated (PWM) Sensor Troubleshooting" procedure prior to replacing the sensor.STOP
NOT OK - The voltage is NOT 8.0 0.5 DCV. The ECM or the machine harness have failed. Proceed to test step 2.Test Step 2. CHECK THE GROUND CIRCUIT OF THE MACHINE HARNESS.
The sensor remains disconnected.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect J1 and J2 machine harness connectors from the ECM.
At the machine harness connector for the sensor, measure the resistance between ground contact B (wire J842-BK(Black)) and connector contact J2-19 (wire J842-BK(Black)). Expected Result:The resistance is less than 5.0 ohms. Results:
OK - The resistance is less than 5.0 ohms. The harness resistance is correct. Proceed to test step 3.
NOT OK - The resistance is greater than 5000 ohms.Repair: The ground circuit in the harness has failed. There is an open circuit between the ground contact and frame ground. Repair the machine harness or replace the machine harness. STOPTest Step 3. CHECK FOR A SHORTED HARNESS.
The sensor and the ECM remain disconnected from the machine harness.
The disconnect switch and the key start switch remain in the OFF position.
Perform the measurements that are listed below at the machine harness connector for the sensor.
Measure the resistance between the signal contact C (wire C453-YL(Yellow)) and contact A (wire K983-BU(Blue)) of the 8 V sensor supply.
Measure the resistance between the connector contact J1-1 (wire 170-YL(Yellow)) of the ECM and contact C (wire C453-YL(Yellow)) of the harness connector for the sensor. Expected Result:The resistance is greater than 5000 ohms. Results:
OK - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. Proceed to test step 4.
NOT OK - The resistance is less than 5000 ohms. Repair: The machine harness has failed. There is a short between the +battery or the 8 V