VW Headlight Switch Repair

by Eric&Barb and Matt Roberds

Copyright (C) 2001, Matt Roberds and Eric&Barb. To the best of our knowledge, we believe that this information is true and correct. However, you use any of this information at your own risk.

Most 1955-1967 VW headlight switches use rivets to hold the contacts on the inside of the switch to the switch body. 1962-1967 switches also use these rivets to hold the push-on wire terminals on the outside to the switch body. For all of these years, the rivets also serve as the electrical connection between the outside terminals and the inside contacts. Over time, these riveted connections can loosen up, leading to increased resistance, heat at the connections, and dim headlights. If your headlights seem dim and the headlight switch gets so hot that you can barely hold the metal switch shaft, it's time to fix it! Fortunately, this is easy to do. You can solder the rivets to the contacts on the inside (and to the push-on wire terminals on the outside on later switches), and clean the internal contacts, to get a much better connection, less heat, and brighter headlights. This page describes how to get into the switch, do the soldering and cleaning, and reassemble the switch.

The first thing you have to do is get the switch out of the Bus. Disconnect the battery negative cable first! The headlight switch is supplied with an unfused wire directly from the battery, so if you skip disconnecting the battery, you will cause sparks and probably a complete wiring harness fire if this wire grounds out on anything! After you've disconnected the battery, unscrew the knob from the switch and take out the screw holding it to the dash. This will let you drop the switch below the edge of the dash where it's easier to see and work with. Label each wire as you disconnect it, according to the numbers molded into the body of the switch. When you have all the wires loose, you'll have something like this. This is a 1962-1967 style switch with push-on wire terminals; earlier switches are similar but have screw terminals.

Front of switch Rear of switch
Click on any picture to enlarge it. Use your browser's "back" button to return here from the enlarged picture.

The key to getting into the switch is the rivets that hold the metal piece on to the plastic base. If you look at the plastic base, where the wire terminals are, you'll see three rivets - two large and one small. Only the two large rivets need to be drilled out. Here's a picture identifying the rivets:
Identifying the rivets

Use a drill bit as big as the head of the rivet, and drill until the head is separated from the rivet. It is best and safest to drill the heads of the rivets off the metal cover on the rear (front is front) of the switch. Drilling at a 20 to 30 degree angle from the hole in the center of the rivet reduces the rivet's tendency to spin with the drill bit - if the rivet is just spinning in its hole, it is impossible for the drill bit to remove the rivet head. Once you have the rivet heads off, rock the metal piece back and forth to separate it from the plastic base. Here are the two pieces you will have at this point:
Metal cover Plastic base and guts

Here's the other side of the small rivet you should NOT have drilled out. It holds one of the contacts for the rheostat (dimmer) for the dash lights.
Small rivet

There are a couple of rubber seals on the shaft. You can leave them on or take them off, but don't lose them. If you take them off, don't forget to replace them later.
Shaft seals

You can operate the switch, if you like, to see how it works. Basically, there is a piece of brass wrapped around the square plastic piece connected to the shaft. This brass piece connects the various contact fingers that come up from the base of the switch. From left to right, here are pictures of the switch in "off", "park", and "on" positions:
Switched off Parking lights Headlights

If you have a US-spec switch, you may have noticed that the plastic piece that moves with the shaft has a different contact arrangement on one side:
Front parking lights detail

This is the contact that turns the "parking lights", "city lights", or "running lights" in the front headlight rims on with the parking lights but off when the headlights are on. It should be under the contact finger connected to terminal 57. If your switch doesn't have a terminal 57, it is a Euro-spec light switch. If you have a switch like this and a Bus with US-spec wiring, connect the front parking light wires (usually two thin gray wires with one connector) to terminal 58 (rear parking lights) on the headlight switch. If you're putting a US-spec switch into a Bus with Euro-spec wiring, just leave terminal 57 disconnected.

Now, to fix it. Mark one side of the plastic piece in the middle and its matching contact finger so you can get it back together the right way (bits of masking tape will do). Pull the shaft and plastic piece all the way out of the switch, noting how the end of the shaft fits into the pocket on the rheostat. Clean all the contact fingers and the brass piece on the plastic block on the shaft with fine sandpaper, and remove any trace of oil or grease from every electrical contact surface. Blow out the residue from sanding. Also, clean off the wire terminals on the outside of the switch with the sandpaper. Bend each internal contact arm inward slightly so it contacts the sliding block firmly. A light coat of dielectric grease on the internal contacts, sliding block, and external wire terminals will greatly reduce oxidation and resistance at the contacts.

Next, solder each of the rivets to its corresponding contact finger. You will need a hot soldering iron for this! I (Matt) tried 100 watt and 140 watt soldering guns for this and neither one was really enough. Eric&Barb use a 325 watt soldering gun, which works much better, helping to draw the solder into the space between the wire terminals and the rivet shafts in the switch body. Be sure to use either solid or rosin-core solder; acid-core solder (as used for plumbing) will eat out the innards of the switch! Thoroughly melted solder will follow heat, so you can apply solder to one side of the rivets, heat the other side of the rivet with the soldering iron, and suck the solder under and between all the pieces. Try not to build up tall "mountains" of solder on the rivets. Remember, the metal cover is going back over all this, and you don't want the solder to short out on the cover. Here's a couple of views of the soldered rivets:

Inside soldering 1 Inside soldering 2

When you're happy with the connections on the inside, solder each rivet to its wire terminal on the outside as well. Pre-1962 switches with screw terminals have a solid connection from the screw terminal to the inside contact, so they don't have rivets on the outside to solder.
Outside soldering 1

Also, check the dimmer switch rheostat. This is a small circle of coiled wire in the very front of the switch. It's behind the plastic insulator in front of the inside contact fingers. If the insulator or the wire are broken, the wire can short out to the metal cover of the switch and leave you with a dead battery. If the insulator or wire are already broken or look like they will soon, you need to remove the insulator and wire completely. Then, solder in a short insulated wire, inside the switch, from terminal 58 to terminal 58b. 16, 18, or 20 gauge wire is fine - whichever one you have handy. This way, the dash lights will come on full bright with the parking lights and headlights, but you will lose the ability to dim the dash lights.

When everything has been soldered, it's time to re-assemble. Put the shaft and plastic piece back in the center of the switch, fitting the end of the shaft into the pocket on the rheostat, and aligning one side of the plastic piece with its corresponding contact finger, using the marks you made earlier. Put the rubber seals back on the end of the shaft if they're off. Carefully line up the metal cover and push it on until it's seated on the plastic base. Hold the cover to the base with one hand and work the switch a couple of times with the other hand to make sure it feels right.

Since you've drilled out the rivets, you'll need some other way to hold the cover on the switch. Small nuts and bolts work well. For the switch in the photos, #4 x 1/2" screws and nuts were used. #6 screws or bolts can also be used. The closest metric sizes to these are M3 and M4, with M3 probably being a better bet. Some switches will require one side of the nuts to be filed flat to fit properly against the bell-shaped metal cover of the switch.

If you want to check your work, you can do so with an ohm-meter or a self-powered timing light. Measure between the metal cover of the switch and each terminal on the back as you work the switch through all its positions. You should show infinite resistance (the light should be off) between the case and every terminal. If you measure low resistance or the light comes on, chances are that the metal cover is shorted to the solder on that terminal inside the switch. Take the cover off and rework that connection.

Once you're happy with the switch, put it back in the Bus. Put the wires back according to the marks you made, screw the switch back into the dash, and put the knob back on. To double-check your work, look at the wiring diagram for your vehicle. Connect the battery ground strap back up, and try it out! You should find that your headlight switch runs cooler, and that your lights are a bit whiter and brighter.

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Last updated Sun Oct 28 14:34:44 CST 2001
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