Electrical problems 98 Ford Taurus

Hello all, I have a 1998 Ford Taurus and a compound electrical issue. The door ajar light is on most of the time but sometimes goes off and the instrument illumination lights dont work. Are these two related? If
so, where would you start to look? The side mirrors dot work and the driver side rear window also dont work.
Thanks,
Tom Gibbs
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voyagergibbs wrote:

I would check ALL the grounds under the hood, including to the firewall, battery cables, and battery to block. (clean and retorque as necessary. Then you need to find where the under the dash grounds are and do the same. Not sure where then are on a gen 3.
Bob
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Bob makes a good point about the grounds. They can cause a lot of strange electrical issues. Certainly check them. In my experience with Ford products in general these problems are usually unrelated, although I've seen them all on the same vehicle at the same time.
Here's what I would do first: Door Ajar Light- usually the pin switch in one of the door latches sticks. You'll also notice that the interior lights may stay on for a long time after you exit the car, about 10 minutes IIRC. Flood the door latches with WD-40 into any crevice the tube will fit into. Aim high, the switch is in the door latch, above the "jaw" area. Then open and close the door about 20 times. The light should go off. Follow up with a shot of white lube (spray lithium grease) in the latches. If the problem returns, one of the switches will need to be replaced. An electrical manual and testing is needed to determine which one.
Left Rear Window- The motor gets "stuck" from non-use or is damaged from kids holding the button in the UP position way too long. Turn the ignition switch on and watch the dome light. Push the window switch to the down position. If the dome light dims just slightly, the motor is "stuck". You may have to do it a few times to really see the dimming. If so, open the door and stand between the door and the car. Push the switch to the Down position and smack the interior panel below the grab handle (toward the bottom of the door) with a rubber mallet, or the side of your fist if you're tough, really hard a couple of times. The window will probably go down and work fine for a while. It will "stick" again eventually so a new window motor is in order soon. (bad spot on the commutator). If you don't get the "dimming" then further testing is needed. You;ll need the electrical manual. (If it dims UP,and not DOWN, the switch is usually bad).
Note: I'm not questioning your intelligence, but I've seen a lot of cases where the user isn't familiar with how the controls work on their car. For the mirrors and inst, panel lights, make sure you know how the controls work. (Again, I only point this out because I've seen it very many times). For the mirrors you twist the knob left or right to adjust the respective mirror. For the Inst. Panel Lamps, the dimmer is a thumbwheel to the right of the headlight switch. Roll it upward to brighten the lamps.
Outside Mirrors- (Make sure you are twisting the mirror knob Left or Right to adjust the left or right mirrors respectively, center is OFF) The biggest culprit is the mirror switch itself. If neither mirror will work in any direction, turn the L/R switch from left to right about 20 times then try it. If the mirrors work now, cool. When the switch stays in the centered position for a long time, the contacts may not conduct well. If not, you'll need to do some more testing and an electrical manual is necessary. (the switch is probably bad)
Inst. Panel Lights-(Make sure the dimmer control is turned all the way up) Check the fuse first and foremost. Is there any aftermarket electronics installed on the car (Radio, lights, etc)? If so, the wiring to the aftermarket things is suspect. If no aftermarket stuff and the fuses are good, the dimmer control for the lights is the usual culprit. The radio display should light up bright with the park/head lights OFF and dim slightly with the lights ON. If the radio goes blank with the lights ON, check the dimmer control setting and the fuse. If that's not the problem, guess what? Yep, further testing is needed.
I hope this helps.
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Thanks Bob and Tom
I got everything lined out except the dimmer but I really want to wait til dark to be sure. The light in the ashtray is in the same circuit I beleive and it does not illuminate but the bulb looks good. With the dimer switch all the way up there is a switch that turns on the dome light. Does that indicate that the dimmer switch is good? I know it is a potentiometer but in the full position and the dome light working that seems to indicate there is a closed circuit. Are they 2 separate circuits?
Thanks,
Tom Gibbs
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wrote:

yes, two seperate things
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If I remember right, the inst panel lamps are supplied by the park lamp circuit through a separate 3(?) amp fuse. Check for power to that fuse with the lights on. If there is power to the fuse, work toward the dimmer. If no power at the fuse, make sure the park lamps work and look in the direction of the headlamp switch. The switch for the dome lamps is part of the dimmer but entirely separate electrically.
Was I anywhere close on the other issues? Just curious.
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Hello Tom,
You were dead on with the other problems. I cant even tell you how much I appreciate the time you must have put into writing the explanations.
Thanks, Tom Gibbs
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Great. Glad to help. I like to check myself from time to time.
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