No spark?

Tiny
JAY CROCKER
  • MEMBER
  • 2002 MERCURY COUGAR
Electrical problem
2002 Mercury Cougar 4 cyl Two Wheel Drive Manual

replaced engine and now have no spark
Thursday, March 4th, 2010 AT 12:53 AM

1 Reply

Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
You should purchase a service manual for your vehicle. This will provide you with illustrations that I can't.

Following is the proper way to diagnose a "No Spark".

Disconnect the wiring harness from your coil pack. Measure voltage from "Start/Run" terminal and ground. (Why you need a service manual for illustrations)

If it measures less than 10 volts, either the harness is bad or the computer isn't sending voltage. (You'll have to do more test)

***Remove the fuel pump relay during this test***

If there's 10+ volts, then connect a test light from the "Start/Run" terminal and each one of the other terminals inside the same connector. (One at a time) crank over the engine. This is a test to see if the computer is telling the coils to fire.

If you computer is checking out fine, the next step is to check the coils. You'll have to make sure your "Grounds" are good. Then measure the ohms of each coil and compare them to spec. (I don't have the specs, but a service manual will)
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Sunday, March 7th, 2010 AT 9:40 PM

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