Fix for marker interrupt switch

2006 Freightliner Columbia: I had a problem that when I would engage this switch I would lose dash lighting and all exterior lights except headlights and flashers. If I flipped my headlight switch to the marker position then everything would work except my headlights. Obviously without headlights you can't drive at night...well, you could but DOT wouldn't like it lol. Anyway, reading another thread on here I traced the issue to the marker interrupt switch. A person suggested this fix but didn't go into detail about HOW to fix it. So, that's what I'll be writing about. FYI, unless you're an electrical guru you HAVE to have a proper functioning interrupt switch. Simply disconnecting the switch WILL NOT solve the problem (I tried).

A. Take apart the dash to gain access to the switches. You can follow this youtube video for a GOOD GENERAL idea on how to do it. Start the vid at about 4:30 http://www.youtube.com/watch?v=AJxrSFw2TFo

B. Disconnect the wire connection from the switch. It should be pretty easy. The connectors are rectangular in shape (like the switch itself) and there's a tab on each end that you can finger press to release.

C. I'm not going to lie - this is the hard part: removing the switch from the dash panel. There's no easy way to do it other than brute force. I ended up taking a flathead screwdriver and prying the top half from the front of the panel (it's ugly I know). Once the top half was leaning out far enough I then used some regular pliers (any blunt solid metal object will do) to push up/in the compression tabs (I can't think of any other name for them) while simultaneously applying pressure on the back of the switch to push the bottom half out. I know that probably sounds complicated but those compression tabs are made out of hard plastic - so some force is required.
C(a). If you're worried about loosening any of the other wires you can disconnect them all from their respective switches. Just label them if you do that!!! Even though this requires more work, it will give you more room with which to work.

D. Once the switch is free from the panel you'll want to open it up using a small screwdriver to pry up some tabs holding it together (easy)



1. These are the compression [b$%&h] tabs I referred to that hold the switch against the panel.
2. These are the metal plates that pivot to connect/interrupt the circuit. You'll want to clean them and apply new lubricant (white lithium grease preferably).
3. These springs allow electricity to flow to the LED inside the switch to light it up. When you put everything back together make sure the orientation is correct. (There's another set of springs pictured here that where part of a mod a did. They won't be there when you open your switch)

E. How it works.


1. When the switch is at rest the top part of the metal plate has electrical contact and thus your [marker/clearance] lights are on.
2. When you engage the switch the bottom part makes contact and your lights turn off.

F.
These white knobs is what makes the magic happen. They slide along the metal plate on the other half of the switch. As you can see there is a spring inside. At rest it uncompresses and pushes the top part of the metal plate to make contact . When the switch is engaged they compress and force the bottom half of the plate to make contact.

FIX A: All you have to do is take some needle nose pliers and gently expand/uncompress/unload that spring. Over time those springs lose their effectiveness. All you're doing is restoring their strength so they exert enough force to push on the metal plates in the rest position. CAREFUL!!! It doesn't take much. Expand it too much and the white knobs will protrude beyond their cubbyhole thus messing up the alignment. If that should happen you'll have to take a blunt [rubber] object (I used my plier's handle) and compress the spring/knob back into the hole as far as it can go and hold it for a couple of seconds. Keep doing that until it sits just inside that hole. You don't want to scratch up the smoothness of the white knobs which are plastic - that's why I said a rubber object.


FIX B: This is a last resort. Take the springs out of two push pens. Affix both springs on the top part of the switch. This method applies sufficient pressure on the top portion of the metal plates when the switch is at rest. The downside to doing this is that the springs are flimsy and have a tendency to bend and make contact with each other (essentially shorting the connection). You will have all your lights but you won't be able to flicker them with the switch anymore. And if that's the case (meaning you don't want to bother with the switch in the future) you might as well short the two plates with a paperclip or something sturdier than springs.


That's all there is to it. Test out the switch [by connecting it] to make sure it works properly. Satisfied? Then put everything back together. Btw, I did this WITH my truck running the entire time so don't worry - doubtful you'll mess anything up. However, if you do opt for option C(a) then turn your truck off since you'll be disengaging the cruise control switch (which allows you to idle for extended periods).