879150053 Mercruiser SENSOR

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SchematicTest Step 1. Verify That the Coolant Level is Acceptable
Ensure that the coolant level for the engine is appropriate. Refer to Operation and Maintenance Manual, "Cooling System Coolant Level - Check" for more information.Expected Result:The coolant is at an acceptable level.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Diagnose the reason for a low coolant level.Refer to the "Troubleshooting Without A Diagnostic Code" section in this manual for more information.Verify that the repair eliminates the problem. Stop.Test Step 2. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect ECM connector J2/P2, and coolant flow switch connector J47/P47. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.Results:
OK - Proceed to Test Step 3.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 3. Check Status of the Coolant Flow Switch on ET
Turn the keyswitch to the OFF/RESET position.
Connect ET to the service tool connector.
Disconnect coolant flow switch connector J47/P47.
Use a suitable piece of wire to short P47:1 (Coolant Flow Switch) to P47:2 (Coolant Flow Switch Return).
Turn the keyswitch to the ON position.
Observe the status of "Engine Coolant Flow" on ET.
Turn the keyswitch to the OFF/RESET position.Expected Result:The status should indicate "Flow" with the jumper wire in place.Results:
OK - The ECM and the wiring are operating correctly. Proceed to Test Step 4.
Not OK - Proceed to Test Step 5.Test Step 4. Check the Coolant Flow Switch
Remove the coolant flow switch from the engine.
Manually close the coolant flow switch. Ensure that excessive force is not required to close the switch.
Measure continuity between J47:1 (Coolant Flow Switch) and J47:2 (Coolant Flow Switch Return) with the switch in the closed position.Expected Result:The switch should close easily and there should be continuity between J47:1 (Coolant Flow Switch) and J47:2 (Coolant Flow Switch Return) with the switch in the closed position.Results:
OK - There may be a mechanical problem with the cooling system of the engine.Repair: Diagnose the cooling system of the engine. Refer to the "Troubleshooting Without a Diagnostic Code" section in this manual.Verify that the repair eliminates the problem. Stop.
Not OK - There is a problem with the coolant flow switch.Repair: Replace the coolant flow switch with a new switch.Verify that the repair eliminates the problem. Stop.Test Step 5. Check for Shorts in the Harness from the Coolant Flow Switch to the ECM
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ECM connector P2
Turn the keyswitch to the OFF/RESET position.
Disconnect ECM connector J2/P2.
Disconnect coolant flow switch connector J47/P47.
Measure the resistance between P2:16 (Coolant Flow Switch) and engine ground.
Measure the resistance between P2:16 (Coolant Flow Switch) and P2:29 (Coolant Flow Switch Return).Expected Result:The resistance should be greater than 20,000 Ohms.Results:
OK - Proceed to Test Step 6.
Not OK - There is a short between the ECM and the coolant flow switch.Repair: Repair the circuit. Stop.Test Step 6. Check for Open Circuits in the Harness from the Coolant Flow Switch to the ECM
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J2/P2 breakout
Turn the keyswitch to the OFF/RESET position and install a 7X-1715 Adapter Cable (40 Pin Breakout) at ECM connector J2/P2.
Use a suitable piece of wire to short P2:16 (Coolant Flow Switch) and P2:29 (Coolant Flow Switch Return) at the breakout.
Disconnect coolant flow switch connector J47/P47.
Measure the resistance between P47:1 (Coolant Flow Switch) and P47:2 (Coolant Flow Switch Return).Expected Result:The resistance should be less than 10 Ohms.Results:
OK - Proceed to Test Step 7.
Not OK - There is a open circuit in the wiring harness between the coolant flow switch and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 7. Check Status of the Coolant Flow Switch on ET at the ECM
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J2/P2 breakout
Disconnect coolant flow switch connector J47/P47.
Use a suitable piece of wire to short P2:16 (Coolant Flow Switch) to P2:29 (Coolant Flow Switch Return) at the breakout.
Turn the keyswitch to the ON position.
Observe the status of "Engine Coolant Flow" on ET.Expected Result:The status should indicate "Flow" with the jumper wire in place.Results:
OK - The ECM is responding correctly.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent. Stop.
Not OK - The ECM is not responding correctly.Repair: Verify your results.Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.Verify that the repair eliminates the problem. Stop.