Question about Mercury Cougar
This is going to take time for you or whomever works on the car to find the problem. There are several methods to use, but the good news is that a simple Ohmmeter, Voltmeter, or testlight is all you need.
First, I suggest taking the vehicle to Autozone or Oreillys and have it scanned for free. Also ask if they would do a Starter Draw test for you. You did not include what model Mercury you have, there were recalls on the Cruise Control module which would never shut off and always drew power.
When you connect the main NEG cable to the Battery. there should not be much of a spark. The onboard computer, clock, and Antitheft will always draw some power. When you have the radio, A/C, and every switch turned off, the balance of the car should be dead.
You have a choice on what you want to do first. In any case you may have to reset the Inertia Switch for the fuel pump by pushing a button on it if the car does not start after you are done.
1. With the NEG cable disconnected, you can open the Black Power boxes under the hood and pull and replace the Relays. Look for green corrosion and fix or clean those Terminals.
2. You can hook up a Voltmeter between the loose NEG cable and the Battery post.
3. After attaching the Voltmeter, with everything off in the car, pull and replace the fuses in the fusebox under the dash until you make the Voltmeter drop.
4. The circuit you kill should have a shorted out part on it. You will either need an Owners manual or leave the fuse out and see what does not work when you reconnect the battery and start the car.
Some items that have caused this problem in Mercury products are Cruise controls, Ignition switches, power seat buttons, window motors, Rear defrosters, and Doorjam switches. If you have Air suspension and an air leak, the suspension will try to pump up the car whether you are in it or not.
I hope the trip to Autozone or Oreillys will save you some of the discomfort on locating your problem.
I hope you feel I have been helpful and Thanks for using Fixya.
Posted on Nov 05, 2010
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Posted on Jan 02, 2017
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