Where's my buzzer?

[Rik]

Hi,

I've seen many on here complain about the "buzzer of doom". I want that too!

My van doesn't have a audible clue for the warning lights, and as it hasn't been that reliable lately i'm constantly looking down nervously to see if a light is on. So I would like a buzzer.

So my question is: where is the buzzer normally, and is there anything special to know about testing/replacing this part?

Thanks!

[R0B]

viewtopic.php?p=8347838&hilit=buzzer#p8347838

[Robsey]

It is in the small L shaped circuit board on the back of speedometer heads in vans from approx 85 / 86 onwards.

[Rik]

Thanks guys, that might be a bit more complicated to fix than I thought.

[TwinTurbo]

most likely the foil PCB on the back of the instrument cluster has failed.

if it was faulty it would be easy to recreate one from scratch if it were not for the random IC that I can't identify.

Re-engineering it is on my backlog of things to do though and is simple enough with modern microcontrollers.

[Robsey]

Reverse engineering for the most part should be quite straight forward if you base your design on what the circuit does, not how it is put together.

The main functions are :-
1 -
Buzzer test with ignition on, but alternator light still on.
Buzzer should stop when engine starts and the charge light goes off on the dash.

2 -
Sound the buzzer when there is insufficient oil pressure to operate the pressure switch behind the water pump, AND the engine speed is above 2000 revs per minute.

I have seen crude rev counters with change-up lights on them.
These could be converted to sound a buzzer when the desired rpm is reached or exceeded, and the oil pressure switch is still at rest.