Ok,,,,98 Ford Expedition, It Started Out With The Lft Rear Brake/signal Not Working. Tried Changing Fuses, All Good. Have Not Been Cited Yet For Lft Tail Light Not Working. Drove Like This For Several Months. Next, The Rt Rear Brake/signal Went Out. The Only Indication Of Brake Lighting I Have Is The Top Brake Light. Both Tail Brake/signal Are Not Working, However, The Parking Lights In The Rear Work Great And The Side Mirrors Signals And Front Headlights Signal Work. Any Sugestions??????

 

ummm. did you change the bulbs, these bulbs have two filaments in them one for tail and one for brake

 

Sorry, I forgot to mention about the bulbs. Yes, I replaced both sides. I was reading my manual and I came up with a couple changes. First Idea was the stoplight/boo switch, but I was told if it was the boo switch is bad then the third brake light on top will not work. Next, I thought a might be a bad ground, but according to the electrical specs, the front/mirror lights share the same ground. After reading further on I came to a conclusion that a may be the multifunction switch. Basically, I'm asking if the MFS switch is going bad, will all the lights (Lft/Rt Front and mirror signal) be affected by it??????

 

It could, but sometimes it isn't necessarily the multifunction switch, but the connector. The locks that hold the individual wires into the connector shell often break, allowing the pins to back out and lose contact with the switch.

 

Thanx, I will look into it....

 

Well I do know for a fact that the multi-function switch controls HEADLIGHT function as well. It was not too terribly bad to replace and was about $70.00.

 

It certainly can be the MFS.... There have been a lot of those issues popping up on here tied to it lately.... 97s and 98s especially from what I've seen....

If the 3rd brake light is working, look at the switch and the connector to it first.

-Joe