How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask A. Penland Your Own Question
A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Mercury
Satisfied Customers: 6667
Experience:  ASE Master Certified. ASE Gasoline Engine Performance Certified,Ford Senior Master Technician
Type Your Mercury Question Here...
A. Penland is online now
A new question is answered every 9 seconds

Mercury Grand Marquis: where is the ignition module located

This answer was rated:

where is the ignition module located on my 2002 mercury grand marquis

Hello and thanks for using Just Answer.I will try my best to help you with your question.

Your 2002 Grand Marquis does not have an ICM (Ignition Control Module) The PCM (Engine Computer) controls all the engine sensors and components. The best thing to do first is to check for any DTCs or codes in the PCM (Engine Computer). Do this first before replacing any parts. ANy auto parts store can do this for you for free.

Get the codes and post them on this page.

Customer: replied 4 years ago.
there are no codes,no check engine lights ive tried that. when it stalls, i give it a jump and it starts right away. seems like when i drive for about 3 miles it does that. can it be the ecm? and why i when to the parts store and asked for such it gave me the part, and i check online for that part its exactly like what i have with the discription of such. the part number from autozone if im not mistaking is P143...
Can you post a picture of it. I cannot locate part number P143...
Customer: replied 4 years ago.
i googled im

Your 2002 Grand Marquis does not have that module. Ford phased that module out in 1999.

Your PCM controls the ignition coils. Your engine has eight of them. In 1999, there was two coil packs and Ford still used spark plug wires. Ford no longer uses them with the new coil on plug ignition system.

When the vehicle stalls, we need to see if you are loosing spark or fuel to the engine. ALso see if the check engine light is on when the engine stalls and is the check engine light goes out when you try to start it.

Customer: replied 4 years ago.
the engine light does come on as the battery light and so on, but doesnt stay on, how would i check for wether im loosing spark or wether the fuel pum is bad/fuel pressure. also i do get water leaks when it rains in the passenger side under the dashboard, and how would you explain me jumping the car and it starts right away. im sorry for being alil pain, but this issue is driving me nuts

Can you better describe "Jumping The Car".

Are you jump starting the vehicle with jumper cables from another vehicle?

Customer: replied 4 years ago.

Ok, that is different. Start the vehicle and check the voltage at the battery. It should be 14.5 volts.

Do this check and let me know what reading you get.

Customer: replied 4 years ago.
it does and sometimes i notice the battery indicator going down and i check the voltage and it reads 13.5 or lil less, also ive checked the alternator it seems ok

The alternator should put out 14.5 volts with the engine running.

Also have the battery properly load tested and also check the battery cables and clamps on the battery post.

Customer: replied 4 years ago.
do you recommend i change the clamps, and can an alternator fail?

The alternator can fail while the engine is running. The best way to isolate the problem, is to place a meter on the battery and measure the voltage till the engine stalls. See what the voltage is. If it drops to 12 volts or lower, replace the alternator.

But if the voltage stays above 13.5 volts, we need to look somewhere else.

Do this test and see what the voltage is when the engine stalls.

Customer: replied 4 years ago.
13.5 volts its an estimate,it could be lower and how do i measure the voltage output from the alternator, sorry all i know is to disconnect the cable from the battery. and in your best opinion you think might be the alternator? or fuel pum?

I think it could be the alternator, because you state you need to jump start the vehicle.

If you have a digital meter that reads volts, touch the battery post, black on negative and red on positive with the battery connected and see what the voltage is.


A. Penland and other Mercury Specialists are ready to help you