Lights Left On Buzzer 83/84

 Headlights Left on Buzzer Modification

This modification has been tested in Mr Squirrel's 1984 Westfalia, Mellow Yellow. Wiring differences between camper versions and standard version of Vanagons as well as changes made to the wiring over the years by Volkswagen and Previous Owners makes it essential that you don't trust any of the information here, and verify your own van's wiring before plunging in. 

Mr Squirrel is not as smart as he wishes he was and has found on more than one occasion that he forgot to turn off the lights. So he put together this warning buzzer. Here's how it goes:

Identifying My Signals

I wanted to find an easy way to wire a buzzer into the van without cutting wires, which means I was limited to working on the fuse panel. So I hoped to find a pair of fuses that could power a small 12VDC buzzer when the ignition is off but the headlight switch is not.

With my trusty voltmeter, I built a "truth table" of fuse voltages, as shown here:

CONDITION						FUSE #
KEY		HEADLIGHT SWITCH
OFF	ON	0	1	2-LO	2-HI	1	2	3	4	5	6	7	8	9	10	11	12
X		X				0	0	0	0	0	0	1	1	1	0	0	0
X			X			1	1	0	0	0	0	1	1	1	0	0	0
X				X		1	1	0	0	0	0	1	1	1	0	0	0
X					X	1	1	0	0	0	0	1	1	1	0	0	0
	X	X				0	0	0	0	0	0	1	1	1	1	1	1
	X		X			1	1	0	0	0	0	1	1	1	1	1	1
	X			X		1	1	1	1	0	0	1	1	1	1	1	1
	X				X	1	1	0	0	1	1	1	1	1	1	1	1

Truth Table for my 1984 Westfalia ONLY. Ignition Key is shown in OFF and ON positions, Headlight Switching is shown in four conditions: Main switch OFF (0), Main Switch set to middle, parking light position (1), Main switch set to ON (2) position and beams set to low, and with beams set to hi. Voltages on the fuses measured under all eight combinations, a "0" indicating no volts, a "1" indicating 12 volts. Build your own truth table for your vehicle before proceeding. 

The condition for when I wanted the buzzer to sound was when the ignition was off, but the light switch NOT off. This is shown in the green section of the table. Next, I needed to find two fuses: one with power under these conditions, and second with no power under these conditions. If I could find such a pair then I could connect the buzzer between them. As can be seen, Fuses #1 and #2 are powered while Fuses #10, #11, #12 have no power in the green section. 

So I have my candidate fuses. 

Testing

Always disconnect the battery ground terminal before fussing around with the electrical bits. 

Using clip leads, I connected my buzzer's red "+" wire to Fuse #2, and the buzzer's black "-" wire to Fuse #12, reconnected the battery and played with the ignition and headlight switches and the buzzer indeed sounded only when the ignition was off but the lights were on. Perfect.

Installation

These instructions assume that you know how to drop the fuse panel and know how to work around the electrical bits. 

Parts I used:

• One buzzer. Radio Shack P/N 273-055A. David Beierl suggested this device. It's designed for 12V, and emits an annoying whine, kind of like Paul Simon.
• Two insulated push-on female quick-disconnect in .250 size, for 18-22 gauge wire. 
• Two .250 quick-disconnect adapters: single-female, dual-male, like Pico Wiring p/n 1595 as shown here: http://picowiring.com/pdf/PICO-11.pdf
• Bit of double-sided sticky tape. 
• Crimping tool.

Crimp insulated female quick disconnects to each of the buzzer's wires. 

Disconnect the battery and pull the fuse panel; work it around so  the backside is accessible. I had to remove Relay #19 to get to the rear of Fuse #12. 

On the rear of Fuse #12, I disconnect the black/yellow wire and install one of the adapters onto the now-unused tab. Push the black/yellow wire back on to one of the two male tabs on the adapter, and push the buzzer's black wire onto the other other tab on the adapter. 

On the rear of Fuse #2, disconnect the gray/red wire, install the other adapter, push the gray/red wire onto one of the two tabs, and push the buzzer's red wire onto the other. 

Reconnect the battery and check for sounding action, in case a crimp has been fumbled.

Use the double-sided tape to affix the buzzer atop one of the relays.

Photos

(Click on images for larger view)

Note: Mr Squirrel is aware that it is not clear how exactly the buzzer finds a path to ground when Fuse #12 is unpowered. But the buzzer only requires 15mA to operate so something is working. 

--Rocky Squirrel 20:20, 24 June 2010 (UTC)

1986 and newer models

For another way, on 1986 and newer models, see this procedure.

--Albell 04:45, 25 June 2010 (UTC)