HARNESS AS-POWER 3844362 - Caterpillar

Use this procedure to troubleshoot the system when one of the following diagnostic codes is active or easily repeated:
262-03 5 Volt Sensor DC Power Supply short to +batt
262-04 5 Volt Sensor DC Power Supply short to groundThe Electronic Control Module (ECM) supplies a regulated voltage of 5.0 0.2 VDC to the following sensors:
Boost pressure sensor
Engine oil pressure sensor
Fuel pressure sensor
Atmospheric pressure sensorThe supply for the +5 V engine pressure sensor is routed from the ECM to terminal A of each pressure sensor connector. The sensor common 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.The +5 V diagnostic code is probably caused by a short circuit to ground or a short circuit to another voltage source in the harness.
Illustration 1 g01119633
Schematic
Illustration 2 g01024457
P2 ECM connector
(P2-15) Boost pressure sensor
(P2-17) Sensor common
(P2-28) Engine oil pressure sensor
(P2-40) Fuel pressure sensor
(P2-57) Atmospheric pressure sensor
(P2-72) +5 V Supply
Illustration 3 g01119636
C13 Sensor locations
(1) Atmospheric pressure sensor
(2) Fuel pressure sensor
(3) Engine oil pressure sensor
(4) Boost pressure sensor
Illustration 4 g01252438
C15 and C18 Sensor locations
(5) Boost pressure sensor
(6) Fuel pressure sensor
(7) Atmospheric pressure sensor
(8) Engine oil pressure sensor
Illustration 5 g01094844
Sensor connector
Test Step 1. Inspect Electrical Connectors and Wiring
Turn OFF the power to the ECM.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM. Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Look for the following diagnostic codes:
262-3
262-4 Note: Wait at least 30 seconds in order