How To:- Improve the Lights On Reminder Buzzer (MK1b)

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As all you MK1b owners will be aware the "Lights On" Reminder buzzer is a pretty pathetic effort. That's because it's basically a relay oscillating at high speed that makes the sound.
I decided to improve it to something more audible and up to date. After some investigation I reckoned I could fit a Piezo buzzer inside the existing relay.
I bought a 12 volt 3-Tone Piezo Buzzer from Maplin (Order Code: KU60Q) for £3.49.


 

Modifying the relay

The relay is brown and is mounted in the top left side of the front boot, remove it from the bracket and take the plug out.

 

 

Use a small screwdriver to unclip the back, remove the circuit board by pushing the pins on the socket.
The case will need a minor modification, I used a Dremel to remove a small rib from the top of the case, you can see that in this picture.

 

 

All the components can be removed from the circuit board either by de-soldering or a pair of snips. Leave the 4 flat pins.
Position the new buzzer on the board as shown and drill a couple of small holes to feed the wires through. There's no need to secure the buzzer to the board as it's a snug fit in the case once assembled.

 

 

 

Replace the circuit board and buzzer back in the case. Solder the Black and Red wires to the board as shown.

 


If the green and yellow wires are connected together a two-tone siren sound is produced; if the green and orange wires are connected together the unit emits a pulsed tone, and if all wires are left unconnected, the output is a continuous tone.
I liked the sound best with all 3 wires joined together, but it's up to you.
replace the back of the relay, refit the relay to the car, refit the plug and the job is done.

Jimi
07/04/09

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