CONE-BEARING 1C3879 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Atmospheric pressure sensor
Auxiliary pressure sensor
Boost pressure sensor
Engine oil pressure sensor
Fuel pressure sensorThis procedure covers the following open circuit diagnostic codes and short circuit diagnostic codes:
94-03 Fuel Pressure open/short to +batt
94-04 Fuel Pressure short to ground
100-03 Engine Oil Pressure open/short to +batt
100-04 Engine Oil Pressure short to ground
102-03 Boost Pressure Sensor open/short to +batt
102-04 Boost Pressure Sensor short to ground
274-03 Atmospheric Pressure open/short to +batt
274-04 Atmospheric Pressure short to ground
1835-03 Auxiliary Pressure Sensor open/short to +batt
1835-04 Auxiliary Pressure Sensor short to groundThe 5 volt sensor supply provides power to all 5 volt sensors. The Electronic Control Module (ECM) supplies 5.0 0.2 VDC to terminal A of each sensor connector. The sensor return from the ECM connector goes to terminal B of each sensor connector. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the 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 a 03 diagnostic code 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 g01212793
Schematic for the engine pressure sensors
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 2 g01166192
Sensor locations (typical engine views)
(1) J2/P2 ECM conntector
(2) J1/P1 ECM conntector
(3) Fuel pressure sensor
(4) Engine oil pressure sensor
(5) Atmospheric pressure sensor
(6) Boost pressure sensor
(7) J61 customer connector
Thoroughly inspect connectors (1), (2), and (7). Also, thoroughly inspect the connectors for each pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01204484
P2 terminal locations
(P2-15) Boost pressure
(P2-17) Sensor return
(P2-28) Engine oil pressure
(P2-40) Fuel pressure
(P2-57) Atmospheric pressure
(P2-72) +5 V sensor supply
Illustration 4 g01212799
P1 ECM connector
(P1-2) +5 V sensor supply
(P1-3) Sensor return
(P1-15) Auxiliary pressure
Illustration 5 g01212800
Terminal locations at the P61 customer connector
(P61-14) +5 V sensor supply
(P61-15) Sensor return
(P61-33) Auxiliary pressure
Illustration 6 g01159881
Sensor connector
(Terminal A) +5 V sensor supply
(Terminal B) Sensor return
(Terminal C) Signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors and on each of the wires in the pressure sensor connectors.
Check the allen head screw for 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 abrasion and for pinch points from the