Test Procedure

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2006 Mercury Mountaineer, 2006 Mercury Monterey, 2006 Mercury Montego, 2006 Mercury Milan, and 2006 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.

DL1 CHECK FOR DTCS

Are DTCs P0116, P0119, P0125, P0128, P1116, P1285, P1288, P1289, P128A, P1290, or P1299 present?

Yes	No
For DTCs P1116 or P1288, GO to DL2. For KOEO and KOER DTCs P1289 or P1290, GO to DL8. For continuous memory DTCs P0119, P1289, P128A, or P1290, GO to DL15. For KOEO or continuous memory DTC P1299, GO to DL21. For continuous memory DTCs P0125 or P0128, GO to DL22. For continuous memory DTC P0116, GO to DL24. For DTC P1285, GO to DL18.	For Temperature Warning Indicator Lamp or Gauge (applications with CHT sensor only) symptom, GO to DL29. For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .

DL2 SELF-TEST DTCS P1288 OR P1116: CHECK THE COOLING SYSTEM

WARNING: TO AVOID PERSONAL INJURY DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR HOT. THE COOLING SYSTEM IS UNDER PRESSURE. STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.

The DTC indicates the temperature sensor is out of self-test range. The engine is not at normal operating temperature.
Check the vehicle coolant level.

Is the cooling system OK?

Yes	No
GO to DL3.	REFER to the appropriate ENGINE COOLING article for cooling system diagnosis. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL3 CHECK IF THE VEHICLE ENGINE STARTS

Attempt to start the engine.

Does the engine start and run normally?

Yes	No
GO to DL6.	GO to DL4.

DL4 CHECK THE RESISTANCE OF THE CHT SENSOR WITH THE ENGINE OFF

NOTE: Refer to the chart at the beginning of this test for the resistance specifications.

Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Is the resistance within specification?

Yes	No
GO to DL5.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL5 CHECK THE CIRCUIT FROM THE MODULE TO THE COMPONENT

NOTE: Refer to the chart at the beginning of this test for the resistance specifications.

CHT Sensor connector connected.
Key ON, engine OFF.
Access the PCM and monitor the CHT V PID.
Using the data collected from the previous step, compare temperature resistance measured at the sensor to the PID temperature voltage measured at the PCM.

Does the measured value at the sensor agree with measured PID value at the PCM?

Yes	No
The concern is elsewhere. RETURN to SYMPTOM CHARTS for further direction.	GO to DL12.

DL6 CHECK THE CHT SENSOR OPERATION

Run the engine until the engine temperature stabilizes.
Verify the radiator hoses are hot and the cooling system is pressurized.
Carry out the PCM self-test.

Are DTCs P1116 or P1288 present?

Yes	No
GO to DL7.	The engine temperature was not stabilized. REPAIR any other DTCs as necessary.

DL7 CHECK THE RESISTANCE OF THE CHT SENSOR

NOTE: Refer to the chart at the beginning of this test for the resistance specifications.

The vehicle must be at normal operating temperature.
Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Is the resistance within specification?

Yes	No
GO to DL31.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL8 DTCS P1289 OR P1290: ACCESS THE CHT PID AND CHECK THE VOLTAGE

Key ON, engine OFF.
Access the PCM and monitor the CHT V PID.

Is the voltage less than 0.2 V?

Yes	No
GO to DL9.	GO to DL10.

DL9 CHECK FOR A GROUNDED CIRCUIT

CHT Sensor connector disconnected.
Key ON, engine OFF.
Access the PCM and monitor the CHT V PID.

Is the voltage greater than 4.6 V?

Yes	No
INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.	GO to DL14.

DL10 CHECK THE CHT CIRCUIT FOR A SHORT TO VOLTAGE

CHT Sensor connector disconnected.
Key ON, engine OFF.

Measure the voltage between:

( + ) CHT Sensor Connector, Harness Side	( - )
CHT	Ground

Is the voltage greater than 5.5 V?

Yes	No
REPAIR the short circuit to PWR. CHECK the CHT sensor for damage. GO to DL11.	GO to DL11.

DL11 CHECK THE RESISTANCE OF THE CHT SENSOR WITH THE ENGINE OFF

NOTE: Refer to the chart at the beginning of this test for the resistance specifications.

Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Is the resistance within specification?

Yes	No
GO to DL12.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL12 CHECK THE SIGNAL AND SIGRTN CIRCUITS FOR AN OPEN IN THE HARNESS

PCM connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Harness Side	( - ) PCM Connector, Harness Side
CHT	CHT
SIGRTN	SIGRTN

Are the resistances less than 5 ohms?

Yes	No
GO to DL13.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

DL13 CHECK THE SENSOR SIGNAL FOR A SHORT TO VREF

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) PCM Connector, Harness Side
CHT	VREF

Is the resistance greater than 10K ohms?

Yes	No
GO to DL31.	REPAIR the short circuit to VREF. CLEAR the DTCs. REPEAT the self-test.

DL14 CHECK THE SENSOR SIGNAL FOR A SHORT TO GROUND

Key in OFF position.
PCM connector disconnected.

Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) PCM Connector, Harness Side
CHT	SIGRTN

Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) 12 Volt Vehicle Battery
CHT	Negative terminal

Is the resistance greater than 10K ohms?

Yes	No
GO to DL31.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

DL15 DTCS P0119, P1289, P1290 OR P128A: INTERMITTENT CHECK

Key ON, engine OFF.
Access the PCM and monitor the CHT V PID.
While observing the PID, carry out the following:
- Tap on the sensor to simulate road shock
- Wiggle the sensor connector

Is there a large change in the voltage reading?

Yes	No
DISCONNECT and INSPECT the connector. If OK, INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.	GO to DL16.

DL16 CHECK THE ELECTRONIC ENGINE CONTROL (EEC) WIRING HARNESS

Access the PCM and monitor the CHT V PID.
While observing the PID, wiggle, shake, and bend small sections of the wiring harness while working from the sensor to the PCM.

Is there a large change in the voltage reading?

Yes	No
ISOLATE the concern. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.	GO to DL17.

DL17 CHECK THE PCM AND VEHICLE HARNESS CONNECTORS

PCM connector disconnected.
CHT Sensor connector disconnected.

Are the connectors and terminals OK?

Yes	No
GO to DL31.	REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL18 SELF-TEST DTC P1285: EARLY WARNING OF ENGINE OVERHEAT CONDITION

NOTE: If the electric cooling fan does not operate, return to SYMPTOM CHARTS GASOLINE MODELS--> for electric cooling fan DTC or symptom diagnosis.

An engine overheat condition is sensed by the CHT sensor.
Check the cooling system for:
- correct coolant level
- internal or external coolant leaks
- blockage of the radiator
- cooling fan operation

Is the cooling system OK?

Yes	No
GO to DL19.	REFER to the appropriate ENGINE COOLING article for cooling system diagnosis. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL19 CHECK THE OPERATION OF THE CYLINDER HEAD TEMPERATURE SENSOR

Run the engine until the engine temperature stabilizes.
Verify the radiator hoses are hot and the cooling system is pressurized.
Check for self-test DTCs.

Is DTC P1285 present?

Yes	No
GO to DL20.	An engine overheat temperature was not detected. REPAIR any other DTCs as necessary.

DL20 CHECK THE RESISTANCE OF THE CHT SENSOR

NOTE: Refer to the chart at the beginning of this test for the resistance specifications.

The vehicle must be at normal operating temperature.
Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Is the resistance within specification?

Yes	No
GO to DL31.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL21 SELF-TEST DTC P1299: INDICATES AN ENGINE OVERHEAT CONDITION

NOTE: Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for possible causes and additional DTC description information.

Check the engine coolant level.

Is the engine coolant fill level correct?

Yes	No
REFER to the appropriate ENGINE COOLING article to diagnose the overheating condition. REPAIR as necessary.	REFER to the appropriate ENGINE COOLING article to diagnose the loss of coolant. REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.	CLEAR the DTCs. REPEAT the self-test.

DL22 SELF-TEST DTCS P0125 OR P0128: CHECK THE ENGINE COOLANT LEVEL

NOTE: DTC P0125 or P0128 indicates the engine coolant temperature has not achieved the required engine operation temperature level, since start-up within a specified amount of time.

Check the engine coolant level.

Is the engine coolant fill level correct?

Yes	No
GO to DL23.	REFER to the appropriate ENGINE COOLING article to diagnose the loss of coolant. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL23 CHECK THE SENSOR OPERATION

Run the engine until the engine temperature stabilizes.
Verify the radiator hoses are hot and the cooling system is pressurized.
Access the PCM and monitor the CHT PID.

Is the temperature greater than 77°C (170.6°F)?

Yes	No
The test is complete. CLEAR the DTCs. REPEAT the self-test.	REFER to the appropriate ENGINE COOLING article for cooling system diagnosis. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL24 DTC P0116: CHECK THE RESISTANCE OF THE CHT SENSOR WITH THE ENGINE OFF

NOTE: Verify the engine temperature is at ambient room temperature before continuing with this test. A soak period of 6 hours may be required. Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for information concerning P0116.

Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Refer to the chart at the beginning of this test for the resistance specifications.

Is the resistance within specification?

Yes	No
GO to DL25.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL25 DTC P0116: CHECK THE RESISTANCE OF THE CHT SENSOR

NOTE: Verify the engine is at operating temperature before taking the CHT reading.

CHT Sensor connector connected.
Run the engine until the engine temperature stabilizes.
Key in OFF position.
CHT Sensor connector disconnected.

Measure the resistance between:

( + ) CHT Sensor Connector, Component Side	( - ) CHT Sensor Connector, Component Side
CHT	SIGRTN

Refer to the chart at the beginning of this test for the resistance specifications.

Is the resistance within specification?

Yes	No
The concern is not present at this time. CARRY OUT the OBD drive cycle to determine if fuel, HO2S, catalyst and misfire monitors can be executed. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE . REPEAT the PCM self-test if necessary.	INSTALL a new CHT sensor. REFER to the appropriate ELECTRONIC ENGINE CONTROLS article . CLEAR the DTCs. REPEAT the self-test.

DL26 DTC P0298: ENGINE OIL OVER TEMPERATURE CONDITION

NOTE: The engine oil temperature protection strategy in the PCM has been activated. This protects the engine against mechanical damage due to overheating. Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for possible causes and additional DTC description information.

Check for an overheating condition and base engine concerns.

Are there any overheating or base engine concerns?

Yes	No
ISOLATE the concern. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.	GO to DL27.

DL27 CHECK FOR CHT DTCS

Check for self-test DTCs.

Are DTCs P1285, P1288, P1289 or P1299 present?

Yes	No
DISREGARD the engine oil temperature (EOT) diagnostic trouble code (DTC) at this time. ADDRESS the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .	GO to DL28.

DL28 ROAD TEST THE VEHICLE AND MONITOR FOR ENGINE OVER TEMPERATURE

Access the freeze frame data (if available) and record the DTC malfunction conditions.
Access the PCM and monitor the CHT V PID.
Test drive the vehicle and allow the engine to reach normal operating temperature.
Observe CHT PID.

Does the engine overheat?

Yes	No
REFER to the appropriate ENGINE COOLING article for cooling system diagnosis. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.	Unable to duplicate or identify the concern at this time.

DL29 ENGINE TEMPERATURE WARNING INDICATOR LAMP ON OR TEMPERATURE GAUGE INDICATES HOT, BUT ENGINE IS NOT OVERHEATING

NOTE: The PCM self-test must be carried out prior to entering this pinpoint test.

Was the PCM self-test carried out prior to entering this pinpoint test?

Yes	No
GO to DL30.	The concern is elsewhere. RETURN to SYMPTOM CHARTS for further direction.

DL30 ENGINE TEMPERATURE INDICATOR LAMP ON OR TEMPERATURE GAUGE INDICATES HOT WITH NO DTCS

NOTE: The engine temperature warning indicator (gauge or lamp) is a warning system that gives the driver information during an engine overheating condition. The PCM monitors the CHT sensor and determines if fail-safe cooling mode is needed. If fail-safe cooling mode is needed, the PCM can signal the driver in 2 ways:

Temperature warning indicator information received through the vehicle communication link (SCP or CAN):
The PCM sends an SCP or CAN message to the instrument cluster to signal an overheating condition. This causes the instrument cluster indicator to illuminate and/or forces the temperature gauge to the H (hot) zone. DTC P1285 is also stored in the PCM.
Temperature warning indicator hard wired to the PCM:
The PCM grounds the engine temperature warning circuit when the engine is overheating. This causes the instrument cluster indicator to illuminate and/or forces the temperature gauge to the H (hot) zone. DTC P1285 is also stored in the PCM.
This pinpoint test ONLY diagnoses the PCM hardwire systems with no PCM DTCs. Currently only the 2.3L Ranger uses the hardwire system.
For any other type of Engine Temperature Warning Indicator system problems, refer to the appropriate INSTRUMENT CLUSTER article .
PCM connector disconnected.
Key ON, engine OFF.

Does the engine temperature warning indicator lamp turn OFF (prove out) and\or the temperature gauge return to the normal zone with the PCM disconnected?

Yes	No
GO to DL31.	The PCM has not attempted to set the warning indicators. REFER to the appropriate INSTRUMENT CLUSTER article to diagnose the temperature gauge. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

DL31 CHECK FOR CORRECT PCM OPERATION

Disconnect all the PCM connectors.
Visually inspect for:
- pushed out pins
- corrosion
Connect all the PCM connectors and make sure they seat correctly.
Carry out the PCM self-test and verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.