Test Procedure

WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2008 Mercury Sable, 2008 Mercury Mountaineer, 2008 Mercury Milan, 2008 Mercury Mariner, and 2008 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

JF1 DETERMINE WHICH COIL IS NOT FIRING PROPERLY

NOTE: Electronic ignition engine timing is entirely controlled by the PCM. Electronic ignition timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.

Determine which coil is not firing properly using the information from Pinpoint Test JB or a DTC and the table at the beginning of this pinpoint test.
Record the suspect cylinder, coil and PCM pin number from the table.
Is the suspect cylinder number, coil driver and PCM pin number recorded?

Yes	No
GO to JF2.	REPEAT the test step to obtain the required information.

JF2 CHECK THE FUNCTIONALITY OF THE SUSPECT COIL DRIVER CIRCUIT

NOTE: This step may cause fuel pump related DTCs to set. Disregard any fuel pump related DTCs at this time.

NOTE: Test lamp bulb filament wattages vary widely. The intensity and duration of blinking depends on the test lamp being used.

Key in OFF position.
Suspect coil connector disconnected.
Remove the fuel pump fuse to disable the fuel pump.
Connect a non-powered test lamp between the IGN START/RUN and suspect coil driver, harness side.
Observe the test lamp while cranking the engine.
Is the test lamp blinking consistently?

Yes	No
GO to JF3.	GO to JF4.

JF3 CHECK THE FUNCTIONALITY OF THE SUSPECT COIL

Key in OFF position.
Carry out a visual inspection. Closely inspect the coil case and boot for carbon tracking, cracks and torn or improperly installed boots.
Remove the suspect COP from the spark plug.
Connect the Air Gap Spark Tester 303-DO37 (D81P-6666-A) or equivalent.
Suspect coil connector connected.
Crank the engine.
Observe the spark tester while cranking the engine.
Is a bluish-white spark present?

Yes	No
refer to PINPOINT TEST Z .	INSTALL a new suspect coil. If necessary, INSTALL a new spark plug. REFER to the ENGINE IGNITION article. CLEAR the DTCs. REPEAT the self-test.

JF4 CHECK THE IGN START/RUN VOLTAGE TO THE SUSPECT COIL

Key ON, engine OFF.
Suspect coil connector disconnected.

Measure the voltage between:

( + ) COP Connector, Harness Side	( - ) Vehicle Battery
IGN START/RUN	Negative terminal

Is the voltage greater than 10 V?

Yes	No
GO to JF5.	For Crown Victoria, Grand Marquis, and Town Car, GO to JF9. For all others, REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

JF5 CHECK THE SUSPECT COIL DRIVER CIRCUIT FOR AN OPEN IN THE HARNESS

Key in OFF position.
PCM connector disconnected.
Suspect coil connector disconnected.

Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) COP Connector, Harness Side
Suspect coil driver	COP

Is the resistance less than 5 ohms?

Yes	No
GO to JF6.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

JF6 CHECK THE SUSPECT COIL DRIVER CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS

Key ON, engine OFF.

Measure the voltage between:

( + ) PCM Connector, Harness Side	( - ) Vehicle Battery
Suspect coil driver	Negative terminal

Is the voltage less than 1 V?

Yes	No
GO to JF7.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

JF7 CHECK THE SUSPECT COIL DRIVER CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS

Key in OFF position.

Measure the resistance between:

( + ) PCM Connector, Harness Side	( - ) Vehicle Battery
Suspect coil driver	Negative terminal

Is the resistance greater than 10K ohms?

Yes	No
GO to JF12.	REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test. If the concern or DTC is still present, GO to JF8.

JF8 CHECK THE SUSPECT COIL FOR DAMAGE

PCM connector connected.
Connect the Air Gap Spark Tester 303-D037 (D81P-6666-A) or equivalent to the suspect coil.
Crank the engine while the accelerator pedal is fully applied.
Observe the spark tester while cranking the engine.
Is a bluish-white spark present?

Yes	No
If necessary, INSTALL a new spark plug. REFER to the ENGINE IGNITION article. CLEAR the DTCs. REPEAT the self-test.	INSTALL a new suspect coil. REFER to the ENGINE IGNITION article. CLEAR the DTCs. REPEAT the self-test.

JF9 CHECK VPWR CIRCUIT CONTINUITY BETWEEN THE SUSPECT COIL AND IGNITION COILS RELAY

Key in OFF position.
Ignition Coils Relay connector disconnected.

Measure the resistance between:

( + ) Ignition Coils Relay Connector, Harness Side	( - ) Suspect coil Connector, Harness Side
VPWR - Pin 3	IGN START/RUN

Is the resistance less than 5 ohms?

Yes	No
GO to JF10.	REPAIR the open circuit. The open is between the splice and the ignition coils relay. CLEAR the DTCs. REPEAT the self-test.

JF10 CHECK THE B+ AND IGN START/RUN VOLTAGE TO IGNITION COILS RELAY

Key ON, engine OFF.

Measure the voltage between:

( + ) Ignition Coils Relay Connector, Harness Side	( - )
B+ - Pin 5	Ground
IGN START/RUN - Pin 2	Ground

Are the voltages greater than 10 V?

Yes	No
GO to JF11.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

JF11 CHECK THE IGNITION COILS RELAY GND CIRCUIT FOR AN OPEN IN THE HARNESS

Measure the voltage between:

( + ) Ignition Coils Relay Connector, Harness Side	( - ) Ignition Coils Relay Connector, Harness Side
B+ - Pin 5	GND - Pin 1

Is the voltage greater than 10 V?

Yes	No
INSTALL a new Ignition Coils relay. CLEAR the DTCs. REPEAT the self-test.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

JF12 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 toFLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) , Programming the VID Block for a Replacement PCM.	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.