SLING-NYLON 1U8221 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Intake manifold air temperature sensor
Coolant temperature sensor
Ambient air temperature sensor
Fuel 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 low
174-03 Fuel Temperature voltage high
174-04 Fuel 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 g01099399
Schematic for engine temperature sensors
Illustration 2 g01099400
P2 ECM connector
(P2-13) Engine coolant temperature
(P2-30) Common for the engine temperature sensors
(P2-56) Intake manifold air temperature
(P2-62) Fuel temperature
Illustration 3 g01099401
P1 ECM connector
(P1-18) Sensor common #1
(P1-26) Ambient air temperature sensor
Illustration 4 g01104079
C15 sensor locations
(1) Fuel temperature sensor
(2) Intake manifold air temperature sensor
Illustration 5 g01104077
C15 sensor location
(3) Coolant temperature sensor
Illustration 6 g03891755
C13 remote fuel filter base sensor location
(1) Fuel temperature sensor
Illustration 7 g03891757
C13 sensor location
(2) Intake manifold air temperature sensor
Illustration 8 g03891760
C13 sensor location
(3) Coolant temperature sensor Test Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the J2/P2 ECM connector, the J1/P1 ECM connector, and the suspect sensor connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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.
Verify that the latch tab of the connector is properly latched.
Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
Check the harness and wiring for abrasions and for pinch points from the sensor to the ECM. 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 pinch points.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem in the