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Brake lights not working after brake pedal switch replaced.
1999 Lincoln Town Car

Brake Lights not working after Brake Pedal Switch replaced.

(1999 Lincoln Town Car)
1999 Lincoln Town Car Brake Light Problem
Recently, while doing "literature drops" for a local political primary election, I drove a 1999 Lincoln Town Car slowly along the street, doing the "curb-side crawl" while another volunteer went door-to-door leaving brochures about our candidate.
This caused me to have my foot on the Service Brake for approximately 5 hours, almost constantly.
Later that day, while in a Wal-Mart parking lot, I couldn't get the column-mounted gearshift out of the "PARK" position.
Knowing that the car couldn't be started without this Brake Pedal Switch engaged, I examined the area around the Brake Pedal, and found a broken wire coming from the Brake Pedal Switch. It had apparently broken through where an after-market remote-starting system had been tapped into the existing wiring (thus allowing the remote-starting system to start the car without depressing the Service Brake Pedal). Up until this point, I didn't know the car had an after-market remote-starting system, and had never used it, so I just disconnected that wire and tucked it out of the way. I also noticed that the black plastic plug attached to the Brake Pedal Switch was partially melted (indicating excessive current flow through the switch).
I removed the melted plug, and used jumper leads with "alligator clips" (which I bought at Wal-Mart) to jump from the remaining wiring remnants under the dashboard to the Brake Pedal Switch (and left the excess "alligator" wiring tucked under the floor mat). However, I still couldn't get the car out of "PARK."
I telephoned a friend who owns a limousine service, to see if he ever encountered this problem with any of his cars. He hadn't, but he accessed a "LincolnForum" website from his office computer and talked me through a procedure which involved:
(1) Applying the Parking Brake
(2) Turning the ignition key fully counter-clockwise
(3) Returning the ignition key back to the "insert" position
(4) Removing the ignition key
(5) Re-inserting the ignition key
(6) Applying the Service Brake
(7) Turning the key to the "ON" position (but not the "START" position)
(8) Moving the gearshift lever into the "NEUTRAL" position (which releases the Parking Brake)
(9) Starting the car in the "NEUTRAL" position.
(10) Moving the gearshift lever into the "DRIVE" position.
This allowed me to get the car home, but the procedure above disables the rear Brake Lights.
This seemed to work for a while, but during the next "literature drop," with my foot almost constantly on the brakes again, one of these temporary leads melted (I could actually smell the melting rubber insulation on the jumper wires.)
Something must be drawing an unusually high amount of current through these wires.
I again replaced the "alligator" jumper wires with a new set, and continued the "literature drop" by periodically putting the gearshift into the "NEUTRAL" position while driving along a fairly level street. Also, since I noticed one of these leads was always "hot" whether the car was running or not. This, I suppose, is so that the Brake Lights will come on, even if the car isn't running.
I left the "alligator" jumper wires disconnected overnight.
This prevented a constant electrical flow through the Brake Pedal Switch and the jumper leads from melting anything again. I wondered if the Brake Pedal Switch was defective.
When my friend's junkyard opened on Monday, I took a replacement Brake Pedal Switch and plug with wiring, from a junked 2000 Mercury Grand Marquis (the switch is identical), and installed it onto the 1999 Lincoln Town Car, using "wire nuts" to connect it to the existing wiring remnants under the dashboard, where the melted plug had been removed.
Brake Pedal switch
The problem is, I still have to use the 10-step procedure above to get the car out of the "PARK" position in the morning, when I first start the car. I have been leaving it in "NEUTRAL" with the Parking Brake set while the car is parked, but this requires me to leave the key in the ignition, as it can only be removed in the "PARK" position. I only do this when I am leaving the car for short periods of time, or where I can keep an eye on it. I still put the car in "PARK" and remove the key and lock it overnight. Then, I have to go through the same 10-step procedure in the morning in order to use the car at all.
The additional problem is, I still don't have Brake Lights. I have been turning on the Parking Lights as I come to an intersection, thus simulating the Brake Lights, for the benefit of the cars behind me, but I cannot continue to do this indefinitely. During the "literature drops" aforementioned, I just drove along slowly with the Emergency Flashers on. This was mainly on very quiet suburban streets over the weekend, with minimal traffic.
However, if I want to use the car for normal travel, especially in heavy traffic, this is not practicable.
I was wondering if there might be a "fuseable link" somewhere that may have burned out, causing the Brake Lights not to work. This could have occurred when the "hot" lead to the Brake Pedal Switch touched some metal under the dashboard. I have checked and swapped out the appropriate fuses (#8 and #20), with no change in symptoms.
I also temporarily re-connected the after-market remote-starting system with an "alligator" jumper wire, to see if that made any difference, which it did not. It is now, once again, disconnected.
I have not checked the light bulbs yet (although I took some extras from the junkyard Mercury). I find it unlikely that they would have both burned out simultaneously.
Any ideas?
Dave
LaserTech2008@yahoo.com
1 answer & 0 comments
Popular Answer
on September 21, 2010
Thanks for the details in your concern; it took a long time to describe it all to be sure.

First: check fuse #10. This is for the Brake Pedal Position switch. With a melted wiring situation, this fuse is almost certainly blown. Check and replace this 20amp fuse if required.

After this...I still would suspect a switch and wiring harness issue. Your used one could also have issues. Or there could be other issues in the wiring that have not been repaired yet. Especially since there has been modifications there in the past. The amount of heat and melting in that harness suggests further damage is possible.

Your brake light switch does a couple of things: 1) allows the shift interlock to release, and enables you to shift out of park. 2) the same switch signal sends power to the brake lights. This is why your shifter will not come out of park. Briefly, you can simply the shift interlock bypass by moving the key in the ignition to the notch felt between "insert" and "on" ("on" is when the dash lights come on, the position prior to "start"). That notch in between is where the interlock is bypassed and you can freely move the shifter.

The brake lights also go through the multi-function switch (turn signal/wiper switch) so you may need to check there too. However, this switch does not affect interlock, so I would doubt any issue is present here.

Bulbs burned out also cannot affect the interlock.

Clearly, check the #10 fuse and then double check the wiring, the connector, and the switch. Good luck!
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Electrical System Diagnosis
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on September 21, 2010
Thanks for the details in your concern; it took a long time to describe it all to be sure.

First: check fuse #10. This is for the Brake Pedal Position switch. With a melted wiring situation, this fuse is almost certainly blown. Check and replace this 20amp fuse if required.

After this...I still would suspect a switch and wiring harness issue. Your used one could also have issues. Or there could be other issues in the wiring that have not been repaired yet. Especially since there has been modifications there in the past. The amount of heat and melting in that harness suggests further damage is possible.

Your brake light switch does a couple of things: 1) allows the shift interlock to release, and enables you to shift out of park. 2) the same switch signal sends power to the brake lights. This is why your shifter will not come out of park. Briefly, you can simply the shift interlock bypass by moving the key in the ignition to the notch felt between "insert" and "on" ("on" is when the dash lights come on, the position prior to "start"). That notch in between is where the interlock is bypassed and you can freely move the shifter.

The brake lights also go through the multi-function switch (turn signal/wiper switch) so you may need to check there too. However, this switch does not affect interlock, so I would doubt any issue is present here.

Bulbs burned out also cannot affect the interlock.

Clearly, check the #10 fuse and then double check the wiring, the connector, and the switch. Good luck!
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