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Radio messy wiring please help!

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I'd love to meet who done this… The radio gets power but is constant terminal 30 and I would prefer terminal 15 to switch with ignition etc so considering starting from scratch, any advise as to where to start? Maybe trace this back to what I need assuming I start with a 15 live, 30 permanent live and 31 ground? After that I'm abit lost, any help would be massively appreciated 

image.jpeg image.jpeg image.jpeg image.jpeg

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Traced it back as far as I can see, coming from the fusebox I have:

2 red
1 brown
1 white & brown
1 blue, 1 blue & brown
1 green 1 green & black disconnected
1 green & red, 1 brown & black (labelled back right?)
1 brown & red, 1 blue & green
Aerial no power I assume just plugs to headunit

Could I cut back to this and make an iso from what I have? image.jpeg

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Oh the joys of 30+ year old stereo wiring

I'm not good at explaining wiring but a the most important part is the constant and switch 12v a multimeter will help with that one

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jellybelly said

Oh the joys of 30+ year old stereo wiring

I'm not good at explaining wiring but a the most important part is the constant and switch 12v a multimeter will help with that one



Tell me about it! I'm only a 19 year old bmw apprentice so I work with shiny new bus systems this is all new to me, I can get a live, 15 switch and ground easy enough it's going from that to an iso that I need abit of guidance with as I've never wired a radio before

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On the iso plug I'm sure (but don't hold me to it) that red is constant and yellow is switch. But not 100%

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jellybelly said

On the iso plug I'm sure (but don't hold me to it) that red is constant and yellow is switch. But not 100%



From what I've read (seen a post which rubjohnny helped on) yellow on the iso is permanent and red is switch just to confuse things! But once I work these out is that all I have to wire to the iso plug and an earth?

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stereo-wiring-harness-adaptor.jpg


you only technically need the 12v constant and a ground but to turn on with ignition will need the switched.

the diagram should give you the information you need, confusion comes with the red and yellows being the other way round because some cars around the 90s mainly German would have it the other way but the stereos are as the diagram shows. this was why stereos wiring blocks come with the bullet connectors to switch these or run them permanently live.

hope this helps.

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with the switched live a favourite is to tap into the blower cable, its the red/black wire. If you want somethign more factory get a 2.8mm latched spade and put it into ignition switch SU, this is live as soon as you pop in the key. check if your ignition switch has the SU pin though, our mk2f polo didnt have this

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

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oh and if its the ce1 fusebox you have a few ignition live spades on the back, look at the G side, 1, 2, 3 or 5 :)

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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mattgee said

stereo-wiring-harness-adaptor.jpg


you only technically need the 12v constant and a ground but to turn on with ignition will need the switched.

the diagram should give you the information you need, confusion comes with the red and yellows being the other way round because some cars around the 90s mainly German would have it the other way but the stereos are as the diagram shows. this was why stereos wiring blocks come with the bullet connectors to switch these or run them permanently live. hope this helps.




That's very helpful thank you! I found this diagram with a iso block for sale and it matches yours so suits well, for illumination do you know where I would get this? Someone told me from sidelight switch image.png

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rubjonny said

oh and if its the ce1 fusebox you have a few ignition live spades on the back, look at the G side, 1, 2, 3 or 5 :)



It's a 1989 clipper with the later blade style fuses not ceramic, is that a ce1?

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Side lights or you could splice from the cig lighter that has illumination and right next to it.

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mattgee said

Side lights or you could splice from the cig lighter that has illumination and right next to it.

Cig lighter sounds oike a good shout, so just wire from the live on that to the illumination on the iso loom?

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most radios dont use the dash illumination wire any more, generally only VW radios make use of it. but the factory wire comes from the back of the connector to the ciggy lighter, look for a snipped grey/blue wire kicking about back there

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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rubjonny said

most radios dont use the dash illumination wire any more, generally only VW radios make use of it. but the factory wire comes from the back of the connector to the ciggy lighter, look for a snipped grey/blue wire kicking about back there



So most modern radios don't need illumination? I'll be fitting a brand new radio

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its used for turning the lighting on, on most aftermarket stereos the back lighting is always on. stereos ive had in the past normally put the lighting into a night mode so the lighting is less harsh compared to day mode where youll want the brightness higher.

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mattgee said

its used for turning the lighting on, on most aftermarket stereos the back lighting is always on. stereos ive had in the past normally put the lighting into a night mode so the lighting is less harsh compared to day mode where youll want the brightness higher.



Ahh right okay, I've taken the iso off the existing loom and had a proper look at what the current set up is running, As you can see in the picture it only has 4 wires, the permanent and switched were both tapped into the same permanent live sothat would explain why its on constantly. The only extra wire other than ground is the blue which I assume is aeriel power? Am I right in saying the original mk1 aerial just plugs into the radio and doesn't require any power? image.jpeg

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Radio messy wiring please help!

The iso block would have been added after manufacture, the ignition you put in yourself as rubjohnny said you'll have to get from the igniton switch or fuse box. Mk1s didn't come with a stereo from factory they were added at the garage. And the stereos were on or off not given an ignition feed like everything now.

I don't know if your aerial should be powered or not depends if it is motorised.

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mattgee said

The iso block would have been added after manufacture, the ignition you put in yourself as rubjohnny said you'll have to get from the igniton switch or fuse box. Mk1s didn't come with a stereo from factory they were added at the garage. And the stereos were on or off not given an ignition feed like everything now.

I don't know if your aerial should be powered or not depends if it is motorised.



Yeah I assumed none of this was a factory fit, my plan is to run that iso with permanent & ground that it already has and then get a switched live as rubjonny helped point out, cut away all the excess mess, and then wire up speakers which is the easy bit; I believe the aerial isn't motorised so should be alright

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My 1988 Gti cabriolet came with a electric aerial as standard, if you look on the inner wing you should see the aerial lead and a couple of wires for the power of the aerial.
Mine gave up and stopped working a couple of years ago so I have not bothered connected to the switch power (blue wire) to it but that wire now switches on my amp and sub in the boot instead.

1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 300,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.
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