Ford Lincoln Mark 8 Headlight Wiring Diagram
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Discussion Starter · #1 ·
Alright, I have some weird electrical issues with this car that at first I thought were unrelated.
1) Key fob NEVER worked - I figured bad battery, fuse, whatever
2) The keypad on the door USED to work, but then it quit
3) The auto-headlights started acting funny - like keeping headlights on during the day so I quit using it.
4) When I open the door, the interior lights come on SOMETIMES. I figured bad pushbutton switch but I changed it and the behavior continues.
5) Trunk light works only sometimes.
These issues seem so flaky. Most of the time I open the door, the interior light does NOT come on, but the green THEFT light flashes every time (car always starts). When I get to where I'm going and pull the key out, when I open the door it seems the inside lights always come on. I just went outside to get something out of the trunk a few minutes ago - I opened the door, the inside lights did NOT come on until I hit the trunk release button (then they came on). Also the light in the trunk was working.
I've checked all the fuses and they're all good (except for the amplifier fuse that I have out because it speakers make noises with it in).
Anyone else have issues like these or have had and found some answers? My next step is to do some pinpoint tests to get some relief.
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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The trunk light and auto-headlamps are independent from the keyless module, but interior lights, the fob, and keypad all run through it. Maybe there's a ground that got loose or maybe the module itself has gone belly-up.
My guess would be to start with replacing the sunlight sensor for the headlamps, and to check the mercury switch in the socket for the light in the trunk (if mine doesn't come on, I give the switch a whack and it comes on 
)
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Discussion Starter · #3 ·
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Check your grounding points for corrosion. It always happens!
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Discussion Starter · #5 ·
Check your grounding points for corrosion. It always happens!
Thanks, I will look at that. Yesterday, I left the car running and ran in to check the mail at the PO Box; my little Shih Tzu, Gizzy, locked the door!
Well, I tried the keypad code and the door unlocked!
I still have the weird issues with the interior lights and I now see in the second wiring diagram down in my above post that there is a lead from the Remote/Keyless Entry Module - it's White/Yellow stripe, connector 457, circuit 707, pin 20 on the module that goes to the trunk light (so the intermittent trunk light may be same issue as I originally suspected).
I don't know if the auto-headlamps work correctly or not - since I had the issue in the past, I just use the headlights manually.
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Discussion Starter · #6 ·
Looks like the key fob just needed batteries! *doh*
Everything seems to work fine now. I guess the interior lights don't like to come on if you unlock the door with the key. The alarm light always flashes until I get the key in the ignition. But now I've changed the batteries in the key fob, the inside lights come on every time I unlock the door (with the fob). I guess it's supposed to work like that.
Auto-headlights are still funky. :zdunno:
Posted by: creatinroom.blogspot.com
Source: https://www.tccoa.com/threads/1995-mark-viii-lsc-electric-issues.141243/
