6025 Mercury PLUG, MAIN JET

Illustration 1 g01455542
Schematic for the engine temperature sensors
Test Step 1. INSPECT THE ELECTRICAL CONNECTORS AND THE WIRING
Remove electrical power from the ECM.
Illustration 2 g01455664
Locations of the engine temperature sensors (typical left side engine view)
(1) J2/P2 ECM connectors
(2) Fuel temperature sensor
(3) Intake manifold air temperature sensor
(4) Engine coolant temperature sensor
(5) Intake manifold #2 air temperature sensor
Thoroughly inspect ECM connectors (1). Also, thoroughly inspect the connectors for sensors (2), (3), and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01455665
P2 terminals that are associated with the engine temperature sensors
(P2-13) Engine coolant temperature
(P2-30) Sensor return
(P2-56) Intake manifold air temperature
(P2-62) Fuel temperature
(P2-91) Intake manifold #2 air temperature sensor
Illustration 4 g01215524
Harness connector for the temperature sensors
(1) Sensor signal
(2) Sensor return
Perform a 45 N (10 lb) pull test on each of the wires at the connectors for the temperature sensors.
Check the allen head screw on each ECM connector 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 sensor to the ECM. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in 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.
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check for an active open circuit diagnostic code 03 or an active short circuit diagnostic code (04). Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: The problem appears to be resolved. The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information.STOP
Not OK - A 03 diagnostic code is active at this time. The ECM detects an open circuit condition. Proceed to Test Step 4.
Not OK - A 04 diagnostic code is active at this time. The ECM detects a short circuit condition. Proceed to Test Step 3.Test Step 3. CREATE AN OPEN CIRCUIT BY DISCONNECTING THE SENSOR CONNECTOR
Remove electrical power from the ECM.
Disconnect the suspect sensor from the harness at the sensor connector.
Restore electrical power to the ECM.
Access the "Active Diagnostic Codes" screen on Cat ET. Check for an active 03 diagnostic code for the suspect sensor. Note: Wait at least 30 seconds for activation of the diagnostic codes.
Remove electrical power from the ECM. Expected Result:A 03 diagnostic code is now active for the suspect sensor.Results:
OK - A 03 diagnostic code became active after the sensor was disconnected.Repair: The problem is with the sensor. Connect a new sensor to the harness connector. Verify that there are no active diagnostic codes for the new sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.STOP
Not OK - The 04 diagnostic code is still present while the sensor is disconnected from the harness. The problem is not with the sensor. There is a problem in the harness between the ECM and the sensor connector. There may be a problem with the ECM. Leave the suspect sensor disconnected. Proceed to Test Step 5.Test Step 4. SHORT THE TERMINALS AT THE SUSPECT SENSOR'S HARNESS CONNECTOR
Remove electrical power from the ECM.
Disconnect the suspect sensor at the harness connector.
Fabricate a jumper wire that is long enough to short circuit the two terminals at the connector for the suspect sensor. Crimp connector pins to each end of the jumper wire.
Install the jumper wire between terminal 1 (sensor signal) and terminal 2 (sensor return) on the harness side of the suspect sensor's connector.
Restore electrical power to the ECM.
Monitor the "Active Diagnostic Codes" screen on Cat ET after installing the jumper wire. Check for an active 04 diagnostic code. Note: Wait at least 30 seconds for activation of the 04 diagnostic code.
Remove electrical power from the ECM. Expected Result:A 04 diagnostic code is now active for the suspect sensor.Results:
OK - A 04 diagnostic code is active when the jumper wire is installed.Repair: The problem is with the sensor. Connect a new sensor to the harness connector. Verify that there are no active diagnostic codes for the new sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.STOP
Not OK - The 03 diagnostic code remains active with the jumper in place. There is an open circuit in the wiring harness between the ECM and the sensor connector. There may be a problem with the ECM. Proceed to Test Step 5.Test Step 5. CHECK THE OPERATION OF THE E