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MG MGF Technical - live 12v feed

Hi

I'm trying to locate a 12volt feed from my F only when the ignition is switched off, spent a few hours yesterday with my trusty volt meter but to no avail, I can only think that there may be one on the alarm but to test the connections I had to unplug it which I think may have meant that they were not showing the correct readings.

Any help appreaciated.

Thanks
Arron
Arron

Arron,

There is a feed to the radio unit (yello wire) which is always on the retain the head unit memory.

If you're not looking at drawing a lot of current, this might suffice.

You can either pull out the head unit or get access to wiring by removing the centre vent.

Cheers!

Sam
Sam Murray

Thanks Sam but I'm actually looking for 12volts when ignition off, zero volts when it is on, I think the yellow radio wire is live all the time for the radio memory.

Thanks anyway
Arron
Arron

I am not sure that there is any signal in the MGF wiring loom that possesses that logic Arron. But it would be easy enough to achieve with two feeds, one constant from the battery, the other switched from the ignition. Then all you'd need is a suitable relay...
Rob Bell

what are you trying to achieve?
Will Munns

Thanks Rob, thats a good idea, I'll investigate.

Will, was thinking about putting in another LED that comes on autommatically when the ignition is turned off, the standard alarm LED on tha dash is not too visable when the roof is down and the sun is shining, was going to install a super bright LED where the blank is for the rear demister.

Thanks
Arron
Arron

At work ,so no data available at the moment BUT isnīt it so that the cig-lighter is feed via a relay? Then there is probably another un-used contact free at that relay . This would give the action you want.
It is really a pain in the .... with modern cars that turns off the lighter outlet when engine stops ! No way to charge a phone or use any other gadget without installing a separate 12Volt ! / Carl.
Carl

Easy one!

you may want to get a pen out

you are expecting the circuit to look like this:

+ve --- +Led- --- resistor --- -ve

add a diode:


+ve --- +LED- ----- resistor --- -ve
ign --- +diode- -^

so the -ve of the diode joins the -ve of the LED.

Now when the ignition is off the LED sees voltage and when the ignition is on the voltage at both sides of the LED is 12v.

this requires a standard (not 12v) led.
Will Munns

This thread was discussed on 20/02/2006

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