NUT 5P7970 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the following sensors:
Engine oil pressure sensor
Fuel pressure sensor
Marine transmission oil pressure sensor
Turbocharger outlet pressure sensorThis procedure covers the following 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 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 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.Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If the CID-FMI 262-03 is logged, it is possible that all of the sensors have been damaged. Repair the sensor supply and check for any "ACTIVE" sensor diagnostic codes in order to determine if a sensor has failed.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 g00945199
Schematic for the engine pressure sensorsTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01150167
C12 engine pressure sensors (typical example) (1) Connector for the marine transmission oil pressure sensor (2) Turbocharger outlet pressure sensor (3) Fuel pressure sensor (4) Engine oil pressure sensor (5) J2/P2 ECM connectors
Illustration 3 g01150173
3406E, C15, and C18 engine pressure sensors (typical example) (1) Connector for the marine transmission oil pressure sensor (2) Turbocharger outlet pressure sensor (3) Fuel pressure sensor (4) Engine oil pressure sensor (5) J2/P2 ECM connectors
Thoroughly inspect connector (5). Thoroughly inspect the connectors for sensors (1), (2), (3), and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01150176
P2 terminals that are associated with the engine pressure sensors (P2-2) +5 VDC (P2-3) Return (P2-14) Marine transmission oil pressure (P2-16) Fuel pressure (P2-24) Engine oil pressure (P2-40) Turbocharger outlet pressure (P2-41) +5 VDC (P2-42) Return
Illustration 5 g01123211
Connectors for the