# Replacing JVC Head Unit



## bazzy (Sep 22, 2010)

Good afternoon.

I am hoping one of the electrical geniuses on here can help me.

I have replaced the JVC head unit in my motorhome with another JVC unit, being a later bluetooth model with mp3 facilities etc.

It was almost a direct swap but black and white plugs went into a supplied wiring harness and the harness plugged into back of head unit.

It works perfectly but the ignition now needs to be switched on first, whereas before I could switch the radio without ignition being on.

In the instructions, there is an option to swap the red and yellow wires around.

Although Fiat isn't mentioned, should I swap them over as shown in diagram? I could of course try it, but I would rather be safe than sorry. :wink2:

Your assistance will be greatly appreciated.

Barry


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## Morphology (Jul 23, 2010)

No harm in swapping the red and yellow to see what happens.

Morph


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## bazzy (Sep 22, 2010)

Morphology said:


> No harm in swapping the red and yellow to see what happens.
> 
> Morph


Thanks Morph.

Just done that and it behaves just the same: needs ignition to be switched on for radio to work.

The yellow lead is a permanent feed from the battery and it's live, but needs a permanent feed also to the red lead (ignition wire).

I'm wondering what the original radio fitter did to the supply to enable radio to work but now new radio doesn't.

Perhaps I'd better visit an auto-technician.


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## javea (Jun 8, 2007)

To enable me to listen to the radio when parked I ran a positive lead from the Leisure battery, via a switch to the lead on the radio originally connected to the ignition. Works perfectly and no danger of running the starter battery down.


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## Robell (Mar 13, 2013)

javea said:


> To enable me to listen to the radio when parked I ran a positive lead from the Leisure battery, via a switch to the lead on the radio originally connected to the ignition. Works perfectly and no danger of running the starter battery down.


Looking at the schematic, that's how I would do it. The yellow lead would be supplying something like a display of a digital clock or similar when the unit is not in use - possibly also to maintain the security code, hence a lot need it to be re-entered after the battery is disconnected. Also, if the yellow lead is connected to the engine battery, you will no doubt have a small constant drain on it, so if you leave the van for any length of time it will drain the battery eventually - but with today's technology I would guess the drain would be miniscule.

.


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## bazzy (Sep 22, 2010)

*A Result at Last*

As all the diagrams said the yellow wire was permanently live, I first disconnected the red wire. Then I connected both yellow and red wires together before they went into receiver. I then taped up the disconnected red wire.

Pics are taken at this stage.

The set didn't switch on.

The loom which was connected to the old JVC receiver only had one permanent live lead and that was red. The yellow lead was only live when ignition was switched on. Perhaps this is why the old JVC set installed by Brownhills when new, worked when ignition was off and the installer switched yellow and red before going into the loom.

Anyway, I re-connected up the red lead to the yellow lead, and left the other yellow disconnected and taped it up.

It now works perfectly.

Thanks to everyone for their help.

Barry:smile2:

By the way, after having the radio disconnected for over 24 hours, the programmed stations were still there!


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## Mikewill (Nov 2, 2018)

*Another new head unit question*



bazzy said:


> As all the diagrams said the yellow wire was permanently live, I first disconnected the red wire. Then I connected both yellow and red wires together before they went into receiver. I then taped up the disconnected red wire.
> 
> Pics are taken at this stage.
> 
> ...


Hello. Have the same issue trying to fit a new Pioneer AVH-Z7100DAB unit to our 2002 B584. It's replacing a Pioneer DEH2430R, which had to be manually switched on and off even if the ignition was on. The loom has incoming red wire connected to both the red and yellow wires going to the unit. The remaining incoming yellow wire is not attached to anything.

The new unit specifically says it cannot be attached to a vehicle without an accessory position on the ignition switch (like the Fiat base vehicle). Has anyone tried to get round this by wiring as described by Barry and as my old unit was wired?

Alternatively, anyone know if it's possible to fit a different ignition switch that does have an accessory position? Otherwise I may have to go down the switched leisure battery route.

Thanks
Mike


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