853722 8 Mercury NUT

Table 1
Troubleshooting Test Steps Values Results
1. Check the Coolant Level
A. Remove electrical power from the ECM.
B. Check the coolant level. Refer to the Operation and Maintenance Manual for the correct procedure to check the coolant level.
Coolant level
Result: The coolant level is low.
Repair: Add coolant according to the procedure in the Operation and Maintenance Manual.
There may be a leak in the cooling system. Identify the source of the coolant leak. Repair the leak. Refer to Systems Operation/Testing and Adjusting, "Cooling System" for additional information.
Result: The coolant is at the correct level.
For applications that have a "Coolant Level Sensor" parameter, proceed to Test Step 2.
For applications that do not have a "Coolant Level Sensor" parameter, proceed to Test Step 3.
2. Verify that the "Coolant Level Sensor" Parameter is Programmed Correctly
This Test Step is only applicable to applications that have a "Coolant Level Sensor" parameter.
A. Connect the electronic service tool to the diagnostic connector.
B. Establish communication with the ECM.
C. Verify that the "Coolant Level Sensor" parameter is programmed to "Installed".
D. Remove electrical power from the ECM.
Parameter programmed
Result: The "Coolant Level Sensor" parameter is not programmed correctly.
Repair: Program the "Coolant Level Sensor" parameter to "Installed".
Verify that the repair eliminates the fault.
Result: The "Coolant Level Sensor" parameter is programmed correctly.
Proceed to Test Step 3.
3. Check the Supply Voltage at the Sensor Connector
A. Disconnect the coolant level sensor at the sensor connector.
B. Restore electrical power to the ECM.
C. Measure the voltage between terminals A (sensor supply) and B (sensor return) at the harness connector for the coolant level sensor.
D. Remove electrical power from the ECM.
8.0 0.5 VDC
Result: The voltage measurement is not correct for the application.
Repair: The sensor supply voltage is not reaching the sensor. There is a fault in the circuit for the sensor supply. Repair the wiring between the sensor and the ECM.
Result: The voltage measurement is correct for the application.
The correct supply voltage is reaching the sensor. Proceed to Test Step 4.
4. Short the Signal Wire to Ground and Monitor the Status for "Coolant Level"
A. Fabricate a jumper wire that is long enough to create a short circuit between two terminals at the coolant level sensor harness connector. Crimp connector pins to each end of the jumper wire.
B. Install the jumper wire between terminals B (sensor return) and C (sensor signal) on the harness connector for the coolant level sensor.
C. Restore electrical power to the ECM.
D. Monitor the status of "Coolant Level" on the electronic service tool while the jumper wire is installed. Wait at least 30 seconds for activation of the status indicator.
E. Remove the jumper wire. Connect the harness connector for the coolant level sensor.
Status change
Result: The status changes from "LOW" to "OK" when the jumper wire is installed. The ECM and the wiring harness to the coolant level sensor are OK.
Repair: Replace the coolant level sensor. Verify that the repair eliminates the fault.
Result: The status does not change from "LOW" to "OK" when the jumper wire is installed.
Repair: The fault is between the ECM and the sensor connector. Repair the wiring. Verify that the repair eliminates the fault.
If the fault is still present, contact the Dealer Solutions Network (DSN).