COMPOUND-JOINT 5P8937 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the system when one of the following diagnostic codes is active or easily repeated:
262-3 5 Volt Sensor DC Power Supply voltage above normal
262-4 5 Volt Sensor DC Power Supply voltage below normalAlso, use this procedure to troubleshoot the system when you have been directed here by another troubleshooting procedure.The following background information is related to this procedure:The Engine Control Module (ECM) supplies regulated +5 Volts DC to the following sensors:
Fuel Rail Pressure Sensor through connector P228
Intake Manifold Pressure Sensor through connector P200
Engine Oil Pressure Sensor through connector P201The supply for the +5 Volt engine sensors is routed from the ECM through the P2 connector to terminal 1 of each pressure sensor connector and to terminal A of the fuel temperature sensor. The supply voltage is 5.0 0.16 Volts DC.The +5 Volt diagnostic code is probably caused by a short circuit to ground or a short circuit to another voltage source in the harness.A diagnostic code can be caused by the following conditions:
A short circuit in the harness
A suspect sensor
A suspect ECM
Table 1
P2 Pin Connections    
Pin on the Pressure Sensor     Function     Fuel Rail Pressure Sensor     Intake Manifold Pressure Sensor     Oil Pressure Sensor    
1     Volts (5V)     48     46     47    
2     Ground     40     38     39    
3     Signal     51     55     56    
Illustration 1 g01758273
Schematic for the sensors
Illustration 2 g01173224
Fuel rail pressure sensor (1) Voltage supply (Vs) (2) Ground (GND) (3) Signal (SIG)
Illustration 3 g01173225
Intake manifold pressure sensor (1) Voltage Supply (Vs) (2) Ground (GND) (3) Signal (SIG)
Illustration 4 g01173226
Oil pressure sensor (1) Voltage Supply (Vs) (2) Ground (GND) (3) Signal (SIG)
Illustration 5 g01543073
Pin locations for the pressure sensors on the P2 connector (38) Ground (GND) Intake Manifold Pressure Sensor (39) Ground (GND) Oil Pressure Sensor (40) Ground (GND) Fuel Rail Pressure Sensor (46) Voltage supply (5 Volt) Intake Manifold Pressure Sensor (47) Voltage supply (5 Volt) Oil Pressure Sensor (48) Voltage supply (5 Volt) Fuel Rail Pressure Sensor (51) Signal (SIG) Fuel Rail Pressure Sensor (55) Signal (SIG) Intake Manifold Pressure Sensor (56) Signal (SIG) Oil Pressure SensorTest Step 1. Check for Connector Damage
Turn the keyswitch to the OFF position.
Check the connectors and the harness for the following faults:
Damage
Abrasion
Corrosion
Incorrect attachment
Refer to Troubleshooting, "Electrical Connectors - Inspect".
Perform a 45 N (10 lb) pull test on each of the wires in the harness that are associated with the pressure sensors and the fuel temperature sensor (if equipped). Check the wire connectors at the following positions:
ECM
Pressure sensorsThe wire connectors are shown in Table 1.
Check the screws for the ECM connectors for the correct torque of 5.0 N m (44 lb in).Expected Result:The connectors and the harness should be free of the following faults: damage, abrasion, corrosion and incorrect attachment.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the connectors or the harness and/or replace the connectors or the harness.Use the electronic service tool in order to clear all logged