Re: Switchable live...

May 23, 2006 7 Replies
W


'92 Audi 80 (B4 Chassis) trying to wire in the cars first radio, there


>is ISO plugs behind the blanking plate but no switchable live to them.

Might sound silly, but are you absolutely sure?


I mean VW's have the permanent and switched live exchanged in the ISO plug, that's an old porblem with them (so much for ISO). But each one I saw had them.


Maybe a previous owner had not known that situation and, to get rid of the unwanted switched one, has cut it off and sealed the blank end?



>Dropped the dash cover, checked power at the ignition, you've got a
>switchable live on the ignition on the smallish red wire when you put
>the key in [1], is that going to be substantial enough to power a modern
>stereo or should I be taking a more substantial feed from somewhere >else?

AFAIK the radios anyway take the power from the permanent live. The switched live is just that: A sign that you want the radio to operate :-)


regards


Wolfgang

Vote
Twitter Facebook LinkedIn
J

Positive, there is only one power wire, the second isn't there at all. The previous (and only owner) has never fitted a radio before.

Vote
Twitter Facebook LinkedIn
W

Then I may make a suggestion as you have aleady the car in pieces :-)

You've found a switched wire, so you might as well slap a relay (radio shack?) behind the radio, route a cable from the permanent live to the relay IN, route a cable from the switched live from the ignition to the relay SWITCH and route a cable from the relay OUT to the proper ISO connector position. Place a fuse in the feed from the permanent live and you're done.

Crude, but it should work just fine. The relay will seperate the circuits, and using the permanent live as the power source and using the switched life from ignition just to switch the relay will make sure you'r not overloading the switched live.

JM2C (make sure the fuse is dimensioned adequately)

Wolfgang

Vote
Twitter Facebook LinkedIn
W

I forgot, somewhere there there must be 'ground' :-)

Wolfgang

Vote
Twitter Facebook LinkedIn
J

Cheers, quick update, your comments about the ISO switch did spur something in my mind. I had perm live at the usual switched live position, and nothing where the perm live should be (factory).

I've cut the wires on the Kenwood side (I'm not cutting the factory wires) so that the perm lives goes to the required perm live, found a suitable switched wire I'm happy with, thought I've got to have full ignition on, put that to the correct place. All is good.

Ta for the input, I'm normally happy with wiring but, normally I'm also used to at least dealing with one thats been screwed with a bit, so you don't mind screwing it up a bit along the way, but this car hasn't, and I'm trying my damndest to at least keeping it looking that way [1], sometimes you just need a bit of secondary input.

[1] So any other changes are reversable too
Vote
Twitter Facebook LinkedIn
W

Glad you could solve that one :-)

Regards

Wolfgang

Vote
Twitter Facebook LinkedIn
C

[snip]

Some didn't have a switched live at all. My MK2 Golf didn't. Wolfgang is right about the switched and permanent being swapped in the connector though, if the switched is present. Some newer radios have swappable wires in the harness to cater for this.

Vote
Twitter Facebook LinkedIn
J

That will explain why I couldn't find switchable in my mk2 golf then ;)

The permanent live was in the wrong place but switched was still missing, no wire to the ISO connector at all. But as covered in the rest of thread, found something I was happy with (though not key in ignition stage) and connected up to it.

There were no funny smells or smoke this morning on the way to work so so far, so good. Tomorrow the cam belts... [1]

[1] Parts 'should' be at the dealers now, booked into garage for that one.
Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required