RETAINER 4J8250 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Boost pressure sensor
Atmospheric pressure sensor
Fuel pressure sensor
Engine oil pressure sensor
Auxiliary pressure sensorThis procedure covers the following diagnostic codes:
094-03 Fuel Pressure open/short to +batt
094-04 Fuel Pressure short to ground
100-03 Engine Oil Pressure open/short to +batt
100-04 Engine Oil Pressure short to ground
273-03 Turbo Outlet Pressure Sensor short to +batt
273-04 Turbo Outlet 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 short to +batt
1835-04 Auxiliary Pressure Sensor short to groundThe troubleshooting procedures for the diagnostic codes of each pressure sensor are identical. The Engine Control Module (ECM) sends a 5 volt supply to terminal A of each sensor. The sensor common connection is connected to terminal B of each sensor. The signal voltage from terminal C of each sensor is sent to the appropriate ECM connector.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 wire, the ECM will generate a -03 diagnostic code.If the sensor is disconnected at the sensor connector, the presence of pull-up voltage at the sensor connector indicates that the signal wire and the return wire from the sensor connector to the ECM are good.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, an open in the return wire, or a short to ground.If the sensor is disconnected at the sensor connector and the voltage on the signal wire at the sensor connector is different from pull-up voltage, the signal wire is shorted to another wire in the harness.
Illustration 1 g01128578
Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01129226
Left side view (1) Boost pressure sensor (2) Atmospheric pressure sensor (3) Fuel pressure sensor (4) Engine oil pressure sensor (5) J2/P2 ECM connector (6) J1/P1 ECM connector
Thoroughly inspect connectors (5) and (6). Thoroughly inspect the connectors for each engine pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01129248
P2 terminals that are associated with the engine pressure sensors (P2-2) +5 VDC (P2-3) Sensor return (P2-14) Atmospheric pressure (P2-16) Fuel pressure (P2-24) Engine oil pressure (P2-40) Boost pressure
Illustration 4 g01129817
P1 terminals that are associated with the engine pressure sensors (P1-2) +5 VDC (P1-3) Sensor return (P1-15) Auxiliary pressure
Illustration 5 g01123211
Connectors for the sensors (A) Supply (B) Return (C) Signal
Illustration 6 g01120120
J61 and P61 terminals that are associated with the engine pressure sensors (14) +5 VDC (15) Return (33) Auxiliary pressure
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine pressure sensors.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check