CLIP 1240174 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Auxiliary temperature sensor
Engine coolant temperature sensor
Fuel temperature sensor
Intake manifold air temperature sensorThis procedure covers the following diagnostic codes:
110-03 Engine Coolant Temperature open/short to +batt
110-04 Engine Coolant Temperature short to ground
172-03 Intake Manifold Air Temp open/short to +batt
172-04 Intake Manifold Air Temp short to ground
174-03 Fuel Temperature open/short to +batt
174-04 Fuel Temperature short to ground
1836-03 Auxiliary Temperature Sensor open/short to +batt
1836-04 Auxiliary Temperature Sensor short to groundThe 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 Electronic 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 a problem 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 OK. If the sensor is disconnected at the sensor connector, the absence of pull-up voltage at the sensor connector indicates a problem in the signal wire. 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 g01146237
Schematic for the engine temperature sensors
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 2 g01167882
Locations of the engine temperature sensors (typical engine view)
(1) J1/P1 ECM connector
(2) J2/P2 ECM connector
(3) Fuel temperature sensor
(4) Intake manifold air temperature sensor
(5) Engine coolant temperature sensor
Thoroughly inspect connectors (1) and (2). Inspect the connectors for sensors (3), (4), and (5). Also, thoroughly inspect the connector for the auxiliary temperature sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01204745
P2 terminals that are associated with the engine temperature sensors
(P2-13) Engine coolant temperature
(P2-30) Sensor return
(P2-56) Intake manifold air temperature
(P2-62) Fuel temperature
Illustration 4 g01212810
P1 terminals that are associated with the auxiliary temperature sensor
(P1-5) Sensor return
(P1-16) Auxiliary temperature
Illustration 5 g01212812
Terminal locations at the P61 customer connector that are associated with the auxiliary temperature sensor
(9) Sensor return
(11) Auxiliary temperature
Illustration 6 g01155187
Harness connector for the temperature sensors
(1) Sensor signal
(2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires at the connectors for the temperature sensors.
Check the allen head screw on each ECM connector and the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from each 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