GEAR-FUEL PUMP DRIVE 7W0508 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Engine oil pressure sensor
Boost pressure sensor
Fuel pressure sensor
Marine transmission oil 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
102-03 Boost Pressure Sensor short to +batt
102-04 Boost Pressure Sensor short to ground
127-03 Transmission Oil Pressure open/short to +batt
127-04 Transmission Oil Pressure 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 J2 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 g01129082
Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01130308
Engine components for the engine pressure sensors (1) J2/P2 connectors (2) Engine oil pressure sensor (3) Boost pressure sensor (4) Connector for the marine transmission oil pressure sensor (5) Fuel pressure sensor
Thoroughly inspect connector (1) and (4). Thoroughly inspect the connectors for each engine pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01130323
P2 terminals that are associated with the engine pressure sensors (P2-15) Boost pressure (P2-16) Marine transmission oil pressure (P2-17) Return (P2-28) Engine oil pressure (P2-40) Fuel pressure (P2-72) +5 VDC
Illustration 4 g01123211
Connectors for the sensors (A) Supply (B) Return (C) Signal
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 the harness and wiring for abrasions and for pinch points from each sensor back 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 harness and