Seat Belt Light Disassembly and Restoration Attempt

[Beetlebaum]

Hey all--

I have a '73 Super Beetle, and I wanted to get the seat belt light working again, so I popped it open and quickly realized that I have no idea how to work with diodes.

The light receives 12v at the connector in the dash, and even when I ground the seat belt wires, the light doesn't work. The bulb is good. There's no continuity between the power and any of the ground places on the light assembly.

Does anyone have any experience or knowledge to help with getting the light working again? (I'm trying to be cheap and avoid buying one in the classifieds; there aren't any of this style there, and it would be neat to have the original light working.)

The underside of the soldered connections:

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Disassembly was easy but a bit nerve-wracking; you need to be careful so that you don't break the old plastic.

Pop off the "FASTEN SEAT BELTS" plastic lens.

The bulb is inside the housing; I used a rubber hose to remove it. Behind the bulb was a papery background, presumably to make the light project out of the lens.

Using small screwdrivers, carefully pry the tabs located on the side of the light housing.

The bulb housing slides apart from the circuitry.

Then the circuitry slides out of the housing.

...and that's as far as I got before I realized that I don't understand it.
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1973 Super Beetle
2003 New Beetle
Post your Super here: http://www.thesamba.com/vw/forum/viewtopic.php?t=331999
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[David_nc_72std]

Is there a number on the transistor (the black circular part on the end)?

The brown cylindrical parts are resistors, if you have a digital meter you can check their resistance, the two with the brown/black/red/silver band should measure 1000 ohms, the green/blue/brown/silver 560 ohms. Those values are approximate, as parts age the value changes, and those type resistors commonly change substantially over time.

Not certain what the cylindrical yellow parts are, my guess would be smaller resistors, could be diodes, but don't recall ever seeing any that color. You can try measuring the resistance across them, if it stays the same when you swap the meter leads around then they are most likely resistors.

Look closely at the solder connections, those can crack and cause bad connections, this often appears as a circular crack around the part leads. From the picture, one of the pins for the bulb holder doesn't appear to be soldered very well. If you resolder any of the connections, the transistor can be damaged by excess heat, so be caution with it.

My guess would be either a resistor has opened up (will show near infinite resistance when measured), or the transistor has gone bad - it works as a switch to turn the light on and off.