VW Dash Switch Testing - Headlight Switch & Headlight Relay:

Video Transcript:

Hi! Sam here with JBugs.com We're going to go over testing some of the electrical components and switches for our car, before we install them, along with our new wiring harness. In this video, we're going to test our original headlight switch and the headlight relay. We're going to start with the headlight switch. We will use a multimeter set to test continuity and we have it set to indicate with an audible beep. We start by testing continuity between the two 30 terminals which are inner connected. 30 is power from the battery and, depending on the car, from the headlight switch out to the fuse box and/or the ignition switch. With our headlight switch at the off position and one lead at our 30 terminal to act as power in, there is no power out to any of the terminals. We only have power at the two 30 terminals, as we should. Next, we pull the headlight knob out to the first position which will be for the running lights and we check for power at the 57 terminal. It isn't used in this car but will be used to power the front running lights only, for models that did use it. The 58 terminal has power and is the terminal for all the running lights. 58B, which is for our dash lights and dimmable via rheostat inside, however is dead. This is common and looking on the opposite side of the switch we can see; as we turn the knob there is a wiper that contacts a wound coil spring which controls the brightness of the dash lights. Despite cleaning the contacts as best we can, we can't get the terminal to work so we'll replace this switch. We continue testing to see if the rest of the contacts work as, in a pinch, you can hook up the dash lights off of the 58 running light terminal, they just wouldn't be dimmable. With the knob pulled all the way out to the second position and a lead at the 30 terminal, we see there is no longer power at the 57 terminal. We do have power at the 58 terminal, as we should. Then we check for power at the 56 terminal and we have nothing. Since 1971 and later headlight switches have an X terminal, we don't have power at the 56 terminal until we have power at the X terminal. The X terminal receives power only when the ignition switch is turned on to help alleviate the chances of having a dead battery by accidentally leaving the lights on when you leave the car. Earlier VW's didn't have this feature. We move our power lead over from the 30 terminal to the X terminal and now we have power at the 56 terminal. If we push the knob back into the first position and still have power at the X terminal, we no longer have power at the 56 terminal. Pulling the knob out once more and we do have power again. Other than the rheostat control, our headlight switch works. That won't do for our car so we grab a new switch. Looking at our new switch compared to our old, we can see we have a different tabbed layout. Looking at the numbered terminals on the back of our switches, we can see that the new switch does not have the 57 terminal. This is fine as looking at the dirt and corrosion on our original switch, we can see there weren't any wires plugged into the 57 terminal or the second 30 terminal for that matter. Keep in mind; a replacement switch may not have all the terminals that your original switch did and the terminals may not be in the same place. While we're at the bench though, we are going to test our new switch. We set a lead at the 30 terminals. At the off position, there isn't power to any of the terminals. At position one on the switch, we have power out to the 58 terminal and now we have power at the 58B terminal. To show the rheostat working, we turn off the audio beep for a moment, so we can watch the meter readout change as we twist the headlight knob. The rheostat now works at both on positions. We turn our meter back on to audible and check our 58 and 58B terminals again, at the first position. Then, we pull out the knob to the second position and they both have power as they should. The 56 terminal again, doesn't have power, until we have power at the X terminal. When we do, our headlight switch works correctly so we can toss out our old switch. Next up, we'll test our headlight relay. We have a late model headlight relay which has a 5th terminal, labeled 30, that earlier relays typically don't have. The 30 terminal must have power for the relay to operate. The other terminals are; 56, 56A, 56B and S. To test the relay, we'll hook a small jumper wire to the 30 terminal so that the relay has power Then, we'll connect it to the 56 terminal to mock up getting power from the headlight switch which we'll provide with a 12 volt jumper box. We hook up a test light to the ground of our jumper box, test that our light works by touching the jumper box lead, then we check our 30 and 56 terminals to make sure they have power. When the headlight switch is turned on, to turn on the relay, the 56B, low beam terminal, should turn on first. We check it and it has power. 56A shouldn't and doesn't have power. To power it up, we need to momentarily ground out the S terminal on the relay. We use another jumper lead, connected to the S terminal. We can demonstrate that when we have our light on the 56B terminal and we touch the ground, the light turns off. Touching the ground again, the lights turn on, and off and on. As we touch the ground, you can hear the relay clicking. The headlights wouldn't actually turn off though as the S terminal toggles the relay back and fourth between the low beam 56B terminal and the high beam 56A terminal. When the 56B turns off, the 56A turns on and back and fourth. Now we know our headlight relay works, so it too can be installed in our car along with the rest of the components we have tested.