864940A01 Mercruiser CARBURETOR ASSEMBLY

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Locations of +5 volt sensors (typical side view)
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Locations of +5 volt sensors (typical top view)
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Schematic for +5 volt sensorsTest Step 1. Inspect Electrical Connectors And Wiring.
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Terminal locations for ECM
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Terminal locations
Thoroughly inspect the following connections:
ECM engine harness connector J2/P2
ECM machine harness connector J1/P1
Turbocharger outlet pressure sensor J200/P200
Engine oil pressure sensor J201/P201
Atmospheric pressure sensor J203/P203
Fuel pressure sensor J208/P208Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the +5 V sensor supply:
P2:2 Engine Pressure Sensor +5 V (G828-WH)
P1:2 Engine Pressure Sensor +5 V (GL730-OR)
P2:3 Engine Pressure Sensor Common (G829-GN)
P1:3 Engine Pressure Sensor Common (993-BN)Refer to Illustration 4.
Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
Check the harness and wiring for abrasion and pinch points from the sensors back to the ECM.Expected Result:All connectors, pins and sockets should be completely coupled and/or inserted and the harness and wiring should be free of corrosion, abrasion or pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - 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. Stop.Test Step 2. Connect the Caterpillar Electronic Technician (Cat ET) and Check for Active Diagnostic Codes
Connect Cat ET to the data link connector.
Turn the keyswitch to the ON position while the engine is OFF.
Monitor the active diagnostic code screen of 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:Select the condition of the following codes:
262-03 5 Volt Sensor Supply short to +batt
262-04 5 Volt Sensor Supply short to groundResults:
Active - Proceed to Test Step 3.
Logged ONLY - Proceed to Test Step 5.
Not Active or Logged - The +5 volt supply is operating correctly at this time. Stop.Test Step 3. Disconnect The ECM Engine Harness Connector From The ECM.
Turn the keyswitch to the OFF position while the engine is OFF.
Disconnect ECM engine harness connector J2/P2.
Turn the keyswitch to the ON position while the engine is OFF.
Access the active diagnostic code screen on Cat ET. Check for one of the following active diagnostic codes:
262-03 5 Volt Sensor Supply short to +batt
262-04 5 Volt Sensor Supply short to groundNote: When ECM engine harness connector J2/P2 is disconnected and the keyswitch is in the ON position, open circuit diagnostic codes will be "Active" or "Logged" for all of the engine sensors. This is normal.Expected Result:The +5 volt diagnostic code is active when the ECM engine harness connector is disconnected.Results:
Yes - The +5 volt diagnostic code is active when the ECM engine harness connector is disconnected.Repair: Temporarily connect a test ECM to ECM machine harness connector J1/P1. Recheck for a +5 volt diagnostic code. If a +5 volt diagnostic code is not active, the original ECM is faulty. Reconnect the original ECM and check the +5 volt diagnostic codes. If a +5 volt diagnostic code becomes active, replace the ECM. Stop.
No - The +5 volt sensor diagnostic code is no longer active when the harness is disconnected. Either the harness or a sensor that is attached to the harness is causing the problem. Reconnect the ECM engine harness connector. Proceed to Test Step 4.Test Step 4. Disconnect The +5 Volt Sensors While Active Diagnostic Codes Are Being Monitored.
Turn the keyswitch to the ON position while the engine is OFF.
Access the active diagnostic code screen on Cat ET. Verify that one of the following diagnostic codes is active:
262-03 5 Volt Sensor Supply short to +batt
262-04 5 Volt Sensor Supply short to ground
Disconnect the following sensors one at a time:
Turbocharger outlet pressure sensor J200/P200
Engine oil pressure sensor J201/P201
Atmospheric pressure sensor J203/P203
Fuel pressure sensor J208/P208
Wait for 30 seconds after each pressure sensor is disconnected while Cat ET is being monitored in order to verify that the disconnection of a specific sensor deactivates the +5 volt diagnostic code.Note: When the sensors are disconnected and the keyswitch is in the ON position, open circuit diagnostic codes will be active or logged when the +5 volt diagnostic codes are no longer active. This is normal. Clear these diagnostic codes after this test step is completed.Expected Result:The original +5 volt diagnostic code remains active.Results:
Yes - The +5 volt diagnostic code is still active. The harness is the cause of the problem. Leave the sensors disconnected. Proceed to Test Step 5.
No - The +5 volt diagnostic code is not active when a specific sensor is disconnected.Repair: Reconnect the sensor that is suspected of causing the problem. If the problem returns after the reconnection of the sensor, disconnect the sensor. If the problem disappears after the disconnection of the sensor, replace the sensor.Clear all diagnostic codes. Verify that the repair eliminates the problem. Stop.Test Step 5. Check the Engine Harness.