ADAPTER-STRAP 7T3354 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Intake manifold air temperature sensor
Engine coolant temperature sensor
Ambient air temperature sensorNote: The ambient temperature sensor is optional equipment.This procedure covers the following diagnostic codes:
105-03 Intake Manifold Air Temperature voltage high
105-04 Intake Manifold Air Temperature voltage low
110-03 Coolant Temperature voltage high
110-04 Coolant Temperature voltage low
171-03 Ambient Air Temperature voltage high
171-04 Ambient Air Temperature voltage lowThe troubleshooting procedures for the diagnostic codes of each temperature sensor are identical. The temperature sensors are passive sensors that have two terminals. The temperature sensors do not require supply voltage from the Engine Control Module (ECM).Pull-up VoltageThe 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 (03) 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 g01251711
Schematic for the engine temperature sensorsTest Step 1. Inspect the Electrical Connectors and the Wiring
Illustration 2 g01251714
Locations of the engine temperature sensors (typical left side engine view) (1) Coolant temperature sensor (2) Intake manifold air temperature sensor (3) J2/P2 ECM connectors (4) J1 ECM connector
Turn the keyswitch to the OFF position.
Thoroughly inspect the connectors for sensors (1) and (2). Also, thoroughly inspect ECM connectors (3) and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01251712
Terminal locations at the P2 ECM connector for the engine temperature sensors (P2-13) Engine coolant temperature (P2-30) Sensor return (P2-56) Intake manifold air temperature
Illustration 4 g01251713
Terminal locations at the P1 ECM connector for the engine temperature sensors (P1-18) Sensor return #1 (P1-26) Ambient air temperature sensor
Illustration 5 g01155187
Terminal locations at the sensor connector for the engine temperature sensors (Terminal 1) Sensor signal (Terminal 2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires in the sensor connector and the ECM connector that are associated with the active diagnostic code.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasions and for pinch points from each of the temperature sensors to the ECM connector.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of