823609A14 Mercury SWITCH, Stop

Probable Causes
Diagnostic codes
Coolant level
Coolant temperature sensor
Radiator and hoses
Radiator cap and pressure relief valve
Water temperature regulator
Engine cooling fan
Quality of coolant
Coolant pump
Cylinder head gasketRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Use the electronic service tool to check for diagnostic codes that relate to the temperature in the cooling system.
Diagnostic Codes
Result: Diagnostic codes are not present.
Return the unit to service.
Result: Diagnostic codes are present.
Proceed to Test Step 2.
2. Coolant Level
A. Check the coolant level.
Engine coolant level
Result: The engine coolant level is low.
Repair: Check the cooling system for leaks. Refer to Systems Operation, Testing and Adjusting, "Cooling System - Test" for additional information. Repair any leaks immediately.
Result: The engine coolant level is OK.
Proceed to Test Step 3.
3. Coolant Temperature Sensor
A. Compare the reading for the coolant temperature on the electronic service tool to the reading for the coolant temperature on a calibrated test gauge.
Coolant temperature sensor
Result: The temperature sensor is not accurate.
Repair: Troubleshoot the circuit and the coolant temperature sensor. Refer to Troubleshooting, "Sensor Signal (Analog, Passive) - Test".
Result: The temperature sensor is reading accurately.
Proceed to Test Step 4.
4. Radiator and Hoses
A. Check the radiator fins for dirt, debris, and/or damage.
B. Check for collapsed hoses and/or other restrictions.
C. Check the radiator for internal blockage.
D. Ensure that the radiator size is sufficient. An undersized radiator does not have enough area for the effective release of heat. An undersized radiator may cause the engine to run at a temperature that is higher than normal. The normal temperature is dependent on the ambient temperature.
Radiator and hoses
Result: The radiator fins are blocked or damaged.
Repair: Remove any dirt and/or debris and straighten any bent fins.
Result: The radiator has internal blockage.
Repair: Remove the blockage.
Result: The radiator fins are not damaged and the radiator does not have an internal blockage.
Proceed to Test Step 5.
5. Radiator Cap and Pressure Relief Valve
A. Pressure-test the cooling system. Refer to Systems Operation, Testing, and Adjusting, "Cooling System" for the correct procedure.
B. Check that the seating surfaces of the pressure relief valve and the radiator cap are clean and undamaged.
C. Check operation of the pressure relief valve and/or the water temperature regulator.
Radiator cap
Result: The pressure relief valve and/or the water temperature regulator are not operating properly.
Repair: Clean the components or replace the components.
Result: The pressure relief valve and/or the water temperature regulator are operating properly.
Proceed to Test Step 6.
6. Water Temperature Regulator
A. Check the water temperature regulator for correct operation. Refer to Systems Operation, Testing, and Adjusting, "Cooling System" for the proper procedure.
Water Temperature Regulator
Result: The water temperature regulator is not operating correctly.
Repair: Replace the water temperature regulator. Refer to Disassembly and Assembly, "Water Temperature Regulator - Remove and Install".
Result: The water temperature regulator is operating correctly.
Proceed to Test Step 7.
7. Engine Cooling Fan
A. Check for a loose drive belt.
Note: A loose fan drive belt will cause a reduction in the air flow across the radiator.
B. Check the engine cooling fan for damage.
Fan and drive belt
Result: The drive belt is not tensioned correctly.
Repair: Tension the fan belt. Refer to Operation and Maintenance Manual, "Alternator and Fan Belts - Replace".
Result: The fan is damaged.
Repair: Repair the fan or replace the fan, as necessary. Refer to Disassembly and Assembly, "Fan - Remove and Install".
Result: The fan is OK and the fan belt is tensioned correctly.
Proceed to Test Step 8.
8. Quality of Coolant
A. Check the quality of the coolant. Refer to the Operation and Maintenance Manual, "Refill Capacities and Recommendations - Coolant".
Coolant
Result: The coolant is not of an acceptable quality.
Repair: Drain and refill the coolant system with coolant of the correct quality. Refer to the Operation and Maintenance Manual, "Refill Capacities and Recommendations - Coolant".
Result: The coolant is of an acceptable quality.
Proceed to Test Step 9.
9. Inspection of the Coolant Pump
A. Inspect the impeller of the coolant pump for damage and/or erosion.
Coolant pump
Result The coolant pump is damaged or not operating correctly.
Repair: If necessary, replace the coolant pump. Refer to Disassembly and Assembly, "Water Pump - Remove" and Disassembly and Assembly, "Water Pump - Install".
Result The coolant pump is not damaged and the pump is operating correctly.
Proceed to Test Step 10.
10. Cylinder Head Gasket
A. Switch off the engine and allow the engine to cool to below normal working temperature. Remove the pressure cap for the coolant system. Start the engine and inspect the coolant for the presence of bubbles or discoloration of the coolant.
Note: If bubbles are present in the coolant or the coolant is discolored, combustion gases may be entering the cooling system.
Cylinder Head gasket
Result: Bubbles are present in the coolant or the coolant is discolored.
Repair: Check the cylinder head gasket. Refer to the recommended action for the cylinder head gasket within Troubleshooting, "Oil Contains Coolant".
Check the cylinder head for flatness. Refer to the recommended action for checking flatness of the cylinder head within Systems Operation, Testing, and Adjusting, "Cylinder Head - Inspect".
Result: There is no evidence of gas leakage into the cooling system.
Contact the Dealer Solution Network (DSN).