DRUM AS 6T0199 - Caterpillar

Use this procedure to troubleshoot any suspect problems with the +5 V sensor supply.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:
Atmospheric pressure sensor
Boost pressure sensor
Engine oil pressure sensor
Fuel 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 return from the ECM connector goes to terminal B of each sensor connector. The 5 V 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 5 V sensor supply and check for any active diagnostic codes for the sensor in order to determine if a sensor has failed.A +5 V diagnostic code is probably caused by a short circuit to ground or a short circuit to another voltage source in the harness. The next likely cause is a problem with a sensor. The least likely cause is a problem with the ECM.
Illustration 1 g01204447
Schematic for the pressure sensor supply
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 2 g01204463
Sensor locations
(1) Intake manifold pressure sensor
(2) Atmospheric pressure sensor
(3) J2/P2 ECM connectors
(4) Engine oil pressure sensor
(5) Fuel pressure sensor
Thoroughly inspect connectors (3). Also, thoroughly inspect the connectors for sensors (1), (2), (4), and (5). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01204484
P2 ECM connector
(P2-15) Intake manifold pressure sensor
(P2-17) Sensor return
(P2-28) Engine oil pressure sensor
(P2-40) Fuel pressure sensor
(P2-57) Atmospheric pressure sensor
(P2-72) Sensor supply
Illustration 4 g01159881
Sensor connector
(A) Sensor supply
(B) Sensor return
(C) Sensor signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and on each of the wires in the pressure sensor connectors.
Check the allen head screw for each of the ECM connectors and the machine connectors 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 of the pressure 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 for each of the connectors are properly in place and ensure that the connectors are completely coupled. Verify that