CAMSHAFT AS 1275412 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the system only when there is an active diagnostic code or when a diagnostic code can easily be activated. This procedure covers diagnostic codes for the following sensors:
Fuel pressure sensor
Engine oil pressure sensor
Injection actuation pressure sensor
Turbocharger outlet pressure sensor
Atmospheric pressure sensor
Turbocharger Inlet pressure sensorUse this procedure for 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
164-03 Injection Acuation Pressure voltage high
164-04 Injection Acuation Pressure voltage low
273-03 Turbo Outlet Pressure open/short to +batt
273-04 Turbo Outlet Pressure short to ground
274-03 Atmospheric Pressure open/short to +batt
274-04 Atnospheric Pressure short to ground
1589-03 Turbo Inlet Air Pressure Sensor open/short to +batt
1589-04 Turbo Inlet Air 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 V supply to terminal A for 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 or the J1 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 g01194096
Schematic for the engine pressure sensors
Illustration 2 g01194099
P1 terminals (P1-2) +5 VDC (P1-3) Return (P1-17) Turbocharger inlet pressure
Illustration 3 g01194101
P2 terminals (P2-2) +5 VDC (P2-3) Return (P2-14) Atmospheric pressure (P2-16) Fuel pressure (P2-24) Engine oil pressure (P2-27) Injection actuation pressure (P2-40) Turbocharger outlet pressure (P2-41) +5 VDC (P2-42) Return
Illustration 4 g01123211
Connectors for the sensors (A) Supply (B) Return (C) Signal
Illustration 5 g01194115
Left side engine view (typical example) (1) Injection actuation pressure sensor (2) Atmospheric pressure sensor (3) Turbocharger outlet pressure sensor (4) Fuel pressure sensor (5) Engine oil pressure sensorTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Thoroughly inspect ECM connectors J1/P1 and J2/P2. Also inspect the connectors for pressure sensors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the sensor connectors that are associated with the