821306T25 Mercury GEAR HOUSING ASSEMBLY

Illustration 1 g02368336
Schematic for the idle/rated speed switchWhen the switch is in the "IDLE" position, the circuit is open. When the switch is in the "RATED" position, a ground signal is supplied to the J1-28 input of the ECM.Test Step 1. Check the Electrical Connectors and the Wiring
Set the engine control to the OFF/RESET position. Remove the electrical power from the engine.
Illustration 2 g01393766
Location of the ECM connectors that are related to the engine speed switch circuit (typical left front engine view) (1) J1/P1 ECM connector
Illustration 3 g01393423
Location of the connectors that are for the engine speed switch (typical left rear engine view) (2) Interface box (3) Engine interface connector (40 pin)
Thoroughly inspect connectors (1) and (3). Thoroughly inspect the connections for the suspect switch. Refer to Troubleshooting, "Inspecting Electrical Connectors".
Illustration 4 g02652899
Terminal locations at the J1/P1 ECM connectors that are for the engine speed switch (P1-28) Idle/rated speed (P1-31) Digital return
Illustration 5 g02652985
Terminal locations at the engine interface connector that are for the engine speed switch (P1-18) Digital return (P1-22) Idle/rated speed
Perform a 45 N (10 lb) pull test on each of the wires in the circuit for the suspect switch.
Check the allen head screw on each ECM connector and the customer connector. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque value.
Check the harness and wiring for abrasions and for pinch points from the battery to the ECM.Expected Result:All connectors, pins, and sockets are coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The wiring and connectors are OK. Proceed to Test Step 2.
Not OK - There is a problem with the wiring and/or a connector.Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.STOPTest Step 2. Test the Switch for Proper Operation
Disconnect the P1 connector.
Use a multimeter to check the resistance of the switch circuits. Insert one lead of multimeter into terminal location P1-28. Insert the other lead of the multimeter into terminal location P1-31.Note: Wiggle the harnesses during the following measurements in order to reveal any intermittent short condition.
Measure the resistance between the P1 terminal for the suspect switch and engine ground.
Activate the switch and measure the resistance again.Expected Result:One resistance measurement indicates an open circuit. The other resistance measurement indicates continuity in the circuit.Results:
OK - One resistance measurement indicates an open circuit. The other resistance measurement indicates continuity.Repair: The switch is operating correctly. The wiring does not have a short circuit or an open circuit. Operate the engine and check the switch for proper operation.If the switch does not operate correctly, there may be a short circuit between the circuit for the suspect switch and another circuit. Carefully reinspect the components. Refer to Troubleshooting, "Electrical Connectors - Inspect". Locate the short circuit and make repairs.STOP
Not OK - Both resistance measurements indicate an open circuit or both resistance measurements indicate a short circuit. There is a problem with the circuit for the switch.Repair: The problem could be in the switch, in the wiring, or in a connector.Carefully reinspect the components. Refer to Troubleshooting, "Electrical Connectors - Inspect".If the inspection does not identify the faulty component, replace the switch and test the switch again.If the problem is not resolved, repair the wiring or the connector. Replace parts, if necessary. Verify that the problem is resolved.STOP