SPRING 1848148 - Caterpillar

System Operation Description:The Engine Control Module (ECM) supplies the following sensors with regulated +5 VDC from the same supply:
J200/P200 Boost pressure sensor
J203/P203 Atmospheric pressure sensor
J201/P201 Engine oil pressure sensor
J204/P204 Injection actuation pressure sensor
J205/P205 Fuel pressure sensor (if equipped)The supply for the +5 V engine pressure sensor is routed from the ECM to terminal A of each pressure sensor connector. The supply voltage is 5.0 0.2 VDC.The +5 V diagnostic code is probably caused by a short circuit to ground or by a short circuit to another voltage source in the harness.
Illustration 1 g01117326
Schematic for engine pressure sensors
Illustration 2 g01117317
Pin locations on ECM connector
(P2-2) Pressure sensor supply (+5 VDC)
(P2-3) Pressure sensor common
(P2-14) Atmospheric pressure sensor
(P2-17) Fuel pressure sensor
(P2-24) Engine oil pressure sensor
(P2-25) Injection actuation pressure sensor
(P2-40) Boost pressure sensor
(P2-41) Pressure sensor supply (engine oil) (+5 VDC)
(P2-42) Pressure sensor common (engine oil) Test Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the J2/P2 ECM connector and the connectors for each analog sensor. 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 analog sensor supply:
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 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 Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 15 seconds in order for the diagnostic codes to become active.Expected Result:One of the following diagnostic codes is active:
232-03 5 Volt supply voltage high (21)
232-04 5 Volt supply voltage low (21)Results:
OK - A 232-03 diagnostic code is active. Proceed to Test Step 3.
Not OK - A 232-04 diagnostic code is active. Proceed to Test Step 4.Test Step 3. Check the Voltage On the +5 V Supply Wire
Turn the keyswitch to the OFF position.
Disconnect all of the following analog sensors at the sensor connector:
Atmospheric pressure sensor J203/P203
Boost pressure sensor J200/P200
Engine oil pressure sensor J201/P201
Injection actuation pressure sensor J204/P204
Fuel pressure sensor J205/P205 (if equipped)
Turn the keyswitch to the ON position.
Measure the voltage between terminal A and terminal B at the sensor connectors. Expected Result:The voltage is 5.0 0.2 VDC.Results:
OK - The voltage is correct.Repair: Replace all wires