BELL AS-SUCTION 7W9020 - Caterpillar

System Operation Description:The Electronic Control Module (ECM) creates a regulated voltage of 5.0 0.2 VDC that is supplied to terminal A of the harness connectors for these sensors:
Turbocharger outlet pressure sensor
Atmospheric pressure sensor
Fuel pressure sensor
Engine oil pressure sensorThis procedure covers the following diagnostic codes:
262-03 5 Volt Sensor DC Power Supply short to +batt
262-04 5 Volt Sensor DC Power Supply short to groundA +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 g01174890
Schematic for pressure sensor supply
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01174896
Left side engine view (typical example)
(1) Fuel pressure sensor
(2) Turbocharger outlet pressure sensor
(3) Atmospheric pressure sensor
(4) Engine oil pressure sensor
(5) J2/P2 ECM connector
Thoroughly inspect ECM connector (5). Also, thoroughly inspect the connectors for each pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01174894
P2 ECM connector
(P2-2) +5 V sensor supply
(P2-3) Sensor return
(P2-14) Atmospheric pressure
(P2-16) Fuel pressure
(P2-24) Engine oil pressure
(P2-40) Turbocharger outlet pressure
Illustration 4 g01159881
Sensor connector
(A) +5 V supply
(B) Sensor return
(C) Signal
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 allen head screw for each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasion and for pinch points from 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 and 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 the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Turn the keyswitch to the ON position.
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for these codes:
262-03
262-04
Determine if the problem is related to a -03 diagnostic code or to a -04 diagnostic code. Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Troubleshooting Without a Diagnostic Code".If the engine is running properly at this time, there may be an intermittent problem in a harness that is causing the codes to be logged. Refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Active -03 code - A -03 diagnostic code is active. Proceed to Test Step 3.
Active -04 code