Ever wonder what's going on inside those chunky Lucas headlamp switches? Wonder no more! The switch on my black '83 Esprit (aka The Fabulous Trashwagon, but that was before the restoration, but I digress) started to get intermittent late last summer. I was cleaning up the shop and decided to take an inventory of what parts I have on hand (another digression) and I found a replacement headlamp switch. So I swapped 'em out (all of 10 minutes and a phillips screwdriver). Tired of counting parts, I took a break and dismantled my old switch. Here is what I found...
The cover is on the right - this changes with application. The center block is the main body of the switch and contains the pins (7) rockers (the copper blades to the ldft and right). There are three copper pivot blades in the middle of the switch body corresponding to the three copper contacts there. The rockers teeter back and forth on the blades. The switch lever is the upper left. Inside the lever are two holes. The pins with springs fit into the holes. As the lever is moved from off to center to top, the pins ride along the rocker, moving them over the pivot blades and making contact with the contacts in the main body.
So, what's wrong with this picture? For one thing, the little black blob between the switch cover and the first rocker is supposed to be attached to the switch body on the right hand side. This tab helps retain the rocker to the pivot blade and center the rocker over the contacts. It is not performing it's proper function as is. The second problem is the left-most pin by the shift lever. It's melted a bit, so it's compromised, but still valiantly tried to perform it's assigned duties.
Here is a closer look at the main body. I have reattached the wayward tab, and you can see the three pivot blades better after a bit of a polish. The bendy bits in the rockers are there to provide the stops and tactile feedback in the switch. The top rocker provides the stop for Off and Headlamps On, the bottom rocker provides the stop for the center Running Lamps On position. The pins ride on the rockers and catch the bends.
Here is the switch with the rockers in place. Off is to the right. I think the top rocker is for lamp control. The bottom rocker is for headlamp pod position. The way the switch works is that the pins in the lever would be pressing on the rockers on the right side. This rocks them to the right, lifting the top rocker off of the pivot blade on the left. This breaks contact for the running lights, and makes contact to lower the headlamp pods. Moving the lever to the center, the bottom rocker does not change position because it is resting on only one pivot blade, which means the pods don't move. The top rocker is now resting on both pivot blades, making contact for the running lamps. Moving the lever to the left pivots both rockers to the left contacts, raising the headlamp pods and turning on the main beams. Everything that is going on with the system doesn't all happen in the switch, there are relays, motors and such reacting to what the switch is doing.
Now the remaining problem
I am pretty sure both pins are supposed to look the same. The one on the left is obviously shorter, and the finish on the closed end looks like it couldn't have been molded that way. I think what happened was the retaining on the switch body broke, which caused a misalignment of the rocker to the contacts. Full contact wasn't maintained, which meant things got hot moving all the current to the headlamps. Hot enough to melt the tip on the pin. As it stands, a replacement pin should be all that is needed to make this switch functional again. I really need to dismantle a working switch to know for sure.
The good news is, these switches can be repaired. Anything plastic can be 3d printed if damaged beyond use, and the copper bits can be carried over. So don't throw those old switches away!