Years ago, I installed a JVC head unit into the Coupe, which needed an ISO connector to enable it to work with the Coupe.

After that, I installed an amp in the boot and ran the blue amp power cable to front of the car and spliced into the blue wire on the ISO connecter. It worked fine for years

However, I have now changed the head unit and it connects directly to the Fiat plugs, so don't need the ISO connector anymore.

I've installed it all and everything works, but I have left the blue amp wire off, as I don't know where to put it.

Obviously, the amp isn't working at the moment (I have the blue cable taped up and tucked into the carpet on the drivers side footwell for now lol).

As said, it's years since I messed around like this and from what I remember, the blue amp wire is the power source and needs to be able to switch off with the head unit.

So, in simple terms, where can I now put the blue amp cable to get the amp working again?

Thanks

Check the new head units manual it should tell you which wire is the one which turns on the amp (usually blue!), you then splice into the correct wire.

Sometimes this is printed on the top of the head unit too.

No extra wires have come with the new head unit, it was just a matter of plugging the Coupes standard plugs straight into the back of it.

I didn't see anything in the instructions (although I didn't really read them properly lol ) or on the head unit regarding the remote amp wire

If you've got the manual it'll be the one marked power antenna on the wiring diagram. Equally if you've got the coupé wiring diagram it's the one for antenna also . Use a scotch lock on the wiring to connect.

Looks like I'm going to have to sit and read the instructions then

I haven't got the Coupes' wiring diagram though.

I haven't got any scotch locks, so it'll be a block connector or twist and wrap with insulation tape

This is all that's specified in the instructions:

I've put the antenna/aerial cable into the plug it's supposed to be in.

Does the above mean I'm supposed to splice into that for the amp wire?

I don't know much about this kind of stuff, but i would imagine, from those instructions that 6. Subwoofer (blue), would be the wire you're after?

As above. It's item 6. Sorry for the lack of clarity, they're not always marked subwoofer. And they're usually in the ISO block.

I'll have a look at this when I next have a free day.

I've got the subwoofer plugged in to the back of the head unit and not too happy about splicing into those wires for the amp.

I'll pull out and recheck the back of the head unit, as something isn't or doesn't sound right here at the moment.

You're welcome to pm me if I can help.

It's hard to tell from your pic what the wires in the top right if the headunit look like; are they just cable/have any ends?

There are no wires coming from the head unit at all, it just has plugs/pins and connectors.

Any wires will be the ones coming from the car going into the head unit, that I put in.

For example, it has two pin connectors built into the back of the head unit. The plugs from the car have just plugged straight into the back of it.

Have you a pic of the back? It does look like there are 3 wires coming out of the headunit above the antenna connector in that picture.

I'll try and get a photo tomorrow evening or Thursday, as I won't need the car then and should have time to pull the head unit back out.

if you have hooked up your stereo to turn on and off with the ignition then use that. the blue wire gives a small current to give to give the amp enough power to fire up. you can however comnect it to any switch live that is fused, but it will be on when the ingition is on. but looking at your pic... it is the blue wire.

After having a few beers on my night off work, I couldn't think of anything better to do at 10pm than disconnect my battery negative lead, pull out the head unit and take some photos

The two Fiat plugs and antenna are plugged in as they should be.

I currently have the sub (one red, one white lead) plugged into the Rear Line Out sockets (rear speakers), left and right, which I think is wrong.

The thin blue wire coming out of the head unit is for Tel muting (don't need).
The purple wire coming out of the head unit is for OE remote (don't need).

Which leaves me with the thicker blue Subwoofer wire which isn't plugged into anything or doing anything at the moment.

Those RCA cables look fine. What's confusing is that blue subwoofer cable.

Given the wires colour and position on the unit I'd suggest it is the switched live you're after. However, it does look confusing.

Have you got a multimeter? Check between the plug center and the chassis for 12 volts switching with the headunit. I think that'll be the only way to know for sure.

I'm glad it's not just me being a girl and getting confused by this

I haven't got a multimeter. If I need to use one, then I know the task is becoming beyond my capabilities

I might just push the head unit back in, connect the battery up and pop to Halfords later to see if they can help a distressed female who currently has no quality sounds coming out of the car

Get a bulb, like a side lamp bulb. Twist some cable on to the legs of the bulb. Fasten on end to bare metal on the chassis (maybe the door check strap would be easiest?). Push other cable into the end of the subwoofer lead (from the headunit). Turn headunit on and watch for the bulb lighting up.

The bulb should be nice and bright if that subwoofer lead is correct. Don't use any bulb bigger that a side light.

I popped to Halfords before I read your last post szkom.

You're right, Halfords also said I need a switched live.

They didn't say anything about the blue subwoofer lead from the head unit and just said I need to find the switched live on the car.

I haven't got time to mess around doing this and just want to know where to put the blue amp wire and get it all working

Job for my bro I think, he has and knows his way around a multimeter

Unless anyone knows which Fiat head unit wire is switched live?

I hate simple jobs like this that turn out to be a pita to do

In the ISO block plug if you go to the top plastic spring tab. On the top row, count 3 pins over from the spring tab. That should be a switched 12 volt out which you can connect your wire to.

why dont you connect it to the sub wire and try it, you never know.

It hasn't got an ISO block szkom, it's plugged directly into Fiat's plugs.



I don't really want to be popping fuses or frying anything if I can help it

I've just had a thought

I think I have my widget spliced into a switched live for the window switch and my boost gauge spliced into the dimmer switch for the dash, which is also switched.

Or vice versa, I can't remember, I have stuff plugged in everywhere

I think I see a further splicing of the window switch (if the blue amp remote cable reaches that far) coming up

T, those plugs are ISO. Try and take the feed from the headunit if you can.

Thanks for the help everyone

I've taken the feed from the window switch, it was easier and I just wanted to get the job done.

All up and running now

Just keep an eye on things. I personally don't like taking additional current from a circuit that isn't stereo related. I've seen things go very wrong when a fault develops.

Thanks szkom and I will do.

All seems ok so far and no burning electric smells yet

Only been used for a few miles back and to work tonight though, so will have to wait and see what it's like on a longer journey.

It's going to be fine most likely. The thing is electrics can do funny things. The way you've wired should be fine. The trouble can come when you have an unusual scenario. Maybe you've got the stereo turned right up, you open the windows, and you've developed some corrosion on one of the contacts in the window circuit. What you have potential for there is voltage to flow where it shouldn't.

Most likely you'll be aware of current flow going positive to negative (in convention). What you may not have come across is potential difference. Which in brief explains current flowing from high to low (12 volts to negative in the case of a car). What it essentially means is that a current will flow from a higher voltage (potential) to a lower. So in the scenario I outlined above maybe, there could be a point where the voltage at the amp end of the blue cable is higher than that of the window circuit.

Like I said probably okay. Just watch for unusual things.