12v relay buzzing at 3v

I've tried the two diodes but it didn't really make it much better so I think ill try a reversed zenor diode can you advise which I need it a 12v system which should max at 21w your help is much appreciated

Just figure out the voltage you want to drop times the current thru it. Presumably the current is just the relay coil current - maybe 200mA - hence 0.2A x 5V = 1W for a 5V drop. Or 4V if 250mA for 1W etc. Zeners commonly come in 400mW, 1W & 5W sizes (but avoid running them at 100% - the lower the better, but ROT no more than (say?) 70-80% of power rating). Zener voltages follow the E24 series from ~3.3V up to ~75V (eg 3.3, 3.6, 3.9, 4.3, 4.7. 5.1...) Are you able to draw the circuit that you have? I assume the fog is still an incandescent bulb - not a LED?

If the wire is at 3 volts, and it is chattering at that voltage, diodes in series should rectify your problem.  I think it will require more than 2 diodes to solve it.  I know theoretically you should lose .7 volts per diode, but in real world applications it is more like .4 volts per diode.  Try 5 or 6 and it should drop the voltage low enough to eliminate the chatter.

Thanks for the reply guys update. I've tried a couple of different types of zenor diodes from my local electronic shop but non of them worked, in forward direction they all passed 3v and 12v and in reverse they all passed no voltage at all, so I think im going to try the diode idea but not keen on having to put 5 in series to lower the voltage. do they have to be wired in daisy chain or can i put them all in a bunch?? Is there not other way to stop anything under 3.5v passing through the circuit what about resistors.

Did you try reversing the zener? Multiple diodes are just like a zener. Resistors won't work (reliably). But I suspect it is a circuit problem - that's why I want you to draw or better describe what you have. Where are the LEDs? Where are incandescent or other bulbs? How is the signal/power being switched? Where is the relay (coil)?

There doesn't have to be a relay in the circuit if there is another of doing it Im just using at the moment to keep them work. The leds are standard lights from the manufacture and have a working voltage of 5v to 1.5 volts I hope this help as i need to sort this prob out pretty soon thanks for your help

The relay wiring doesn't look right, give us the terminal connection numbers.

The wiring to the relay is right because it works All I've none is pick the feed to the relay from the fog light switch wire which has 3.5v on it when the side lights are on and then jumps to 12v when press the fog switch

Phew - it works! My apologies, I thought you were still having problems. Otherwise I'd question the commoning of 12.5V & 3.5V, and especially 30 & 86 (NO-in & coil). You did put the diode(s) between 30 & 86? Sorry - that is now irrelevant.

Yes i put them in series with the feed