With these cars getting older, some creature comfort and luxury features are starting to wear out. Nowhere is this more evident than with the power door locks. One day they work fine, the next they might stop altogether. This section will help you to troubleshoot the power door locks.

Really, power door locks in our cars run from a pretty simple system. Power from the fuse box is fed through relays (behind the dash on 1983-86 cars, underneath the passenger seat on 1987-88 cars), which is then fed to the switches on either door panel. From there the power is fed to the door lock solenoids which are buried inside the door, behind the door panels. Here are some basic procedures for tracking down the problem:

• If you press the door lock button (both the "lock" and "unlock") and hear the relays clicking in both directions, then the problem is more than likely with the solenoid or the switch.
• If you don't hear the relays clicking, or hear one but not the other, then you have a bad relay.

If a switch or relay change does not solve the problem, you will pretty much have no choice but to remove the door panel and at least test the stock power door lock solenoid. The solenoid is usually a goldish or silver color with a rubber boot, and is attached to a bracket that is pop-riveted onto the door frame. The hook end of the solenoid loops through the door latch mechanism. It's a pretty tight reach into the area so be careful (and also remember to put your window up first!).

Your first instinct may be to just punch out the pop rivet to remove the solenoid, and that's fine. Upon reinstallation you'll need to use a bolt, nut and some washers. However, Jason has passed along this alternate method of removing the solenoid:

Reach your arm inside the door and grab hold of the solenoid. There is a bracket that holds the solenoid (you know the one, most of you drilled the rivet to remove it). The solenoid has two pins that hold it to the bracket. Twist it, one of the pins will come out of the bracket. Then pop the other side out.

Now that it's out of the bracket, unhook it from the door latch. The wiring harness simply pulls off from the bottom. Once the hook is off the latch mechanism (just be patient), you can fully remove the solenoid from the door. To test it, get the harness from inside the door and plug it back into the solenoid. Use your power door lock switch to see if the rod does indeed move up and down. If not, or if you have sporadic success, then you will definitely need to get another solenoid.

About that new solenoid: if you're thinking about taking a trip to the Ford dealer to order a new one, you won't find it listed for a Cougar or Thunderbird. At last check it was available for a Lincoln Mark VII, though. Or you can use a Mustang solenoid. Basically most Ford vehicles used the same solenoid. The only thing that differs is the rod, with both its length and its end configuration. Some rods have an "S" shape, and some have a "J"-shaped hook. You can use any solenoid and just switch over your rod, if you so wish. But if you're looking for a direct swap, the Mark VII solenoid is the one to get.

You can always get a used solenoid from the boneyard, and that's okay. Just be aware that you may end up with a bad one, or one that will go bad perhaps sooner than later.

Before you install your new or used door lock solenoid, lift up the rubber boot and apply some white lithium grease. This will keep it lubricated for a long time and keep water from infiltrating the mechanism.

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