Do I need a new headlight switch?

[Marrs]

Took the car out for her December jog and when I came back I felt something different in the headlight switch when I turned it off, I turned it back to position 1 for the parking lights (PL) but the PL didn't come on, I turned it to position 2 and just before it clicked the PL came on and if I twist to fully engage the headlights, they will come on as they normally do. The odd thing is when I have it far enough between position 1 and 2 in order for the PL to activate the dash lights also come on as they should, but now when I switch to Position 2 they go off then the headlights come on, so dash lights only work when PL are on, not with the headlights.

Does this sound like the headlight switch itself is bad? It definitely doesn't have the solid two position clicks it did and now feels almost like the first click is "worn" but the dash light strangeness threw me off. Is this best sourced through Classic Center, I prefer new so it will last another 50-years but not if it's $300 or something for the switch.

[Marrs]

I am replacing this next week, has anyone else done this before? Will I be able to replace the switch with the dash in place, there are an awful lot of wires connected to the back. Also, what are the chances of all the insulation cracking as I maneuver the switch down to work on? I am not looking forward to this.

[dirtyharry]

its good you're not looking forward to it, I dont think it will be a fun job, not sure if the switch is 2 pieces or not, you may be able to split it in half? and leave the terminal(s) side all connected... I've had the switches come loose from the dash, where you go to turn it and you can tell the whole thing is rotating behind the dash.... sounds like yours is probably actually worn. the thing with the dash lights is a little strange... but more then likely switch related. I cant remember if the switch is held by a bracket or not... its more then just the retaining nut on the dash, you may have to pull the tach/cluster as well.

[Marrs]

I think the whole thing comes out, the back is held on to the rest using rivets so I am out of luck there. Oh well, I'll have a new one in there and hopefully won't need to do this job for another 50-years.

[250 Coupe]

The headlight switch in my 450SEL failed in much the same way. Either the case cracked or the rivets gave out and the switch separated enough to make the spring loaded ball not snap into the detents and the contacts not make contact every time.

It wasn't a big job to replace, just take your time and do one wire at a time or take lots of pictures since there are approximately 4000 wires going to the switch.

Michael

[Marrs]

Originally Posted by 250 Coupe

It wasn't a big job to replace, just take your time and do one wire at a time or take lots of pictures since there are approximately 4000 wires going to the switch.

Hi Michael, thanks for the encouragement. Our cars are different I realize but were you able to access your switch easily from below and only had to pivot the switch and its wires down to see where each one goes or what is your best advice on how to see and manipulate the wires/screws at the same time?

[Squiggle Dog]

This is a typical occurance. Your switch should consist of a metal housing peened over a bakelite terminal block. Most of the time you can use a punch or even the end of a chisel and after pushing the terminal block into the housing (they tend to separate and cause a loose switch--same goes for the ignition switch) hit it with a hammer to push the peened lip into the terminal block so it all fits tightly.

If the assembly falls apart, you can take this opportunity to lubricate the moving parts of the switch with dielectric grease on the contact points. The factory service manual has a diagram for where each wire attaches.

[250 Coupe]

Originally Posted by Marrs

Hi Michael, thanks for the encouragement. Our cars are different I realize but were you able to access your switch easily from below and only had to pivot the switch and its wires down to see where each one goes or what is your best advice on how to see and manipulate the wires/screws at the same time?

You are right, I was able to pivot the switch down to see it. To be honest, I don't remember how I got it out but I'm sure it was detailed in the shop manual. In the process of getting it out where I could see it, it basically exploded and while I probably could have put it back together, I had a new switch and felt better putting it in rather than putting the old one back together.

If you can't get it out far enough to see, you could make up some labels based on the numbers next to each terminal on the replacement and put them on the wires by feel but IIRC, there are some unused terminals and that could get confusing.

Michael

[Marrs]

I opted for a new headlight switch I was able to source and installed it this morning. It was much easier than I anticipated, but only because I was able to twist myself around to get in the right position to see and handle everything. I'd say if you happen to be more Rubenesque in size, have fat fingers or can't squat or lie down that low it is not a job for you to attempt.

I didn't take pics but it's pretty simple. First, I disconnected the battery. I then pulled the black headlight knob straight off, then unscrewed the retaining collar for the headlight switch which allowed it to be pushed backwards and out of the dash. There was no other retaining device on my car. I could feel that the wiper switch and the bulb fixture for the shifter indicator (automatic car) were helping to hold the switch in place so I then unscrewed the black knob for the wiper switch and pulled the shifter bulb straight back towards the firewall to remove it from the housing. This is all done with feel, no eyes on any of this, hence the need for smaller hands, acrobatic ability and patience. I was then able to rotate the headlight switch with all it's wires attached up, then towards the firewall then down towards me again which gave me enough wire length to easily do the job. I could now see the markings on the switch so I knew which wires I was removing. I simply started with the double wires since there is only one set of those and worked my way around noting the one spot that was unused on my car. Once finished I rotated everything back up in the reverse of how I moved it down originally, replaced the wiper switch, bulb then finally the headlight switch. I am not sure if there is anything to help position the switch but put your black knob back on before you tighten the chrome collar fully and be sure it is oriented properly.

I was concerned about wire insulation cracking but these were insulated with fabric so it was not an issue.

My old switch did simply come uncrimped from the base, so I will take it apart just to educate myself on it's design and may use it as a spare for when this one goes out in another 50-years.

[Palolo]

Originally Posted by Marrs

I didn't take pics but it's pretty simple. First, I disconnected the battery.

Oh, go ahead and take all the fun out of having your hand in confined quarters with exposed wiring terminals...

Originally Posted by Marrs

This is all done with feel, no eyes on any of this, hence the need for smaller hands, acrobatic ability and patience. I was then able to rotate the headlight switch with all it's wires attached up, then towards the firewall then down towards me again which gave me enough wire length to easily do the job.

Makes one wonder what kind of elves the factory used to employ to do things like install heater valves & levers, switches, etc.

The elf union's contract must not have been renewed, hence the onset of robot-built 116s, and the end of a manufacturing era. Imagine, no more dashboard elves or hvac gnomes... That was it.