DRUM AS-GEAR 3P0329 - Caterpillar

System Operation Description:This test procedure is used for the active temperature sensor. The active sensor has a three-wire electrical connector.Use this procedure under the following conditions:Use this procedure if another procedure has directed you here. Use this procedure if any of the following diagnostic codes are active:
0171-03 Ambient Air Temperature Sensor voltage above normal
0171-04 Ambient Air Temperature Sensor voltage below normalPull-up VoltageThe Electronic Control Module (ECM) continuously outputs a pull-up voltage on the circuit for the sensor signal wire. The ECM uses this pull-up voltage in order to detect an open in the signal circuit. When the ECM detects the presence of a voltage that is above a threshold on the signal circuit, the ECM will generate an open circuit diagnostic code -3 for the sensor.If the sensor is disconnected at the sensor connector, the presence of pull-up voltage at the sensor connector indicates that the wires from the sensor connector to the ECM are not open or shorted to ground. If the sensor is disconnected at the sensor connector, the absence of pull-up voltage at the sensor connector indicates an open in the signal wire or a short to ground. If the sensor is disconnected at the sensor connector and the voltage at the sensor connector is different from pull-up voltage, the signal wire is shorted to another wire in the harness.
Illustration 1 g01983794
Schematic for air ambient temperature sensor
Illustration 2 g01983795
Air ambient temperature sensor connector
(A) Sensor +5 Volt supply
(B) Sensor return
(C) Sensor signal
Illustration 3 g01983796
A typical view of the P1 connector (harness side) pin locations.
(33) Sensor return
(41) Sensor +5 Volt supply
(56) Sensor signal Test Step 1. Inspect Electrical Connectors And Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the ECM engine harness connector and the connector for the air ambient temperature sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the air ambient temperature sensor.
Verify that the latch tab of the connector is correctly latched.
Check the allen head screws for each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness for abrasions, for pinch points, and for corrosion. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness is free of corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a fault in the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are correctly installed and ensure that the connectors are completely coupled.If necessary, perform the "Wiggle Test" on the electronic service tool.Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.STOPTest Step 2. Check the Supply Voltage at the Sensor Connector
Remove the electrical power from the ECM.
Disconnect the harness connector for the air ambient temperature sensor.
Restore the electrical power to