We’re going to dive deeper into the VW electrical system and start by breaking down the main connection or distribution point for the electrical system which is the headlight switch. For most all VW models, the power (+) from the battery (or voltage regulator) is connected to the headlight switch and then distributed to the fuse box and ignition switch. That means that all the electricity in your VW runs to and from your headlight switch. Most importantly, the wire from the battery is not fused! This is why we recommend running a circuit breaker or large fuse at the battery or regulator for the main power wire. Typically a fuse rated for slightly above your charging system is used, for instance with a 30 amp generator, we run a 50 amp breaker or fuse. For a 55 amp alternator we'd run a 75 amp, etc.

At the headlight switch, where all the wires plug in, if you look closely you’ll see some numbers next to all the terminals. Below is a breakdown of those terminals, what they hook up to and what they operate.

30 – 2 or 3 “30” terminals – red wires (large gauge). Main battery (+)
power to the switch from the battery, which passes through the switch to
the fuse box, and in some models to the ignition switch.  These terminals always have power whenever the battery is hooked up

56 – 1 terminal only – white-black wire (large gauge) - power (+) to the headlight dimmer switch or headlight relay. This terminal only has power when the headlight knob is pulled all the way out to the second position and turns on the headlights.

57/57L/57R – 1 or 2 terminals - white-red/white-black wire (small gauge) - power (+) to front parking lights. This terminal only has power when the headlight knob is pulled out to the first position. Originally VW hooked up the front parking or running lights to this terminal directly. This terminal is not typically used nowadays as the circuit was not fused from VW. We normally run the front parking lights off the 58 powered terminals at the fuse box nowadays.

58/58L/58R – 1 or 2 terminals – grey wire (small gauge) – power (+) to front and rear running lights. This terminal has power when the headlight knob is pulled out to the first or second position. The terminal is hooked up to the fuse box to power the running lights.

58b – 1 terminal – white-red wire (small gauge) – power (+) to the instrument lights. This terminal has power when the headlight knob is pulled out to the first or second position. The terminal is powered by a rheostat in the headlight switch which allows the dash lights to be dimmed by turning the headlight knob. The terminal connects to the various dash gauge lights.

X – 1 Terminal – black-yellow/red-black wire (large gauge) – power (+) to the headlight circuit from the ignition switch. 1971 and later model VW headlight switches use the X terminal to control the headlights. Unless the headlight switch has power at the X terminal, the headlights won’t turn on. The running, parking and dash lights will still operate as normal. This prevents someone from leaving their headlights on while the car is parked. This won’t prevent the other lights from draining the battery if the headlight switch is left on though.

Hopefully this information along with our other electrical blogs, online tips on our switch pages and How To Videos will help you get your VWs electrical system back in order!

Sam Mebane