Technical Head unit not powering up

[Howard]

Right I have a '96 Cinquecento SX. The tape/FM radio in it isn't stock, just some Philips/Fiat crap. Works fine.
Luckily it has an ISO connector. It's already got some sort of wiring harness adaptor from when the garage (My dad works there) has fitted this old stereo.

Anyway I took delivery of my new head unit today (Pioneer DEH-P3630MP). It's a birthday present but I checked it out, hooked it up to ensure everything worked, etc. This is where I encountered problems. Quite simply, it didn't work. Lol.
The Pioneer appears not to be getting any power at all. "Oh ********, I've blown a fuse" I thought. But upon plugging in the old stereo, it works fine.

So does anyone have any idea what's up, before I send my dad to work with it to have a look at?

I'm thinking it might possibly be something to do with the fact that the Cinq's stereo wiring doesn't include ignition-power on as standard, and this might have something to do with it. But the wiring harness/ISo connector in the car has a little yellow jumper lead going from the +12v ACC pin to the +12V battery one, so the same power is going to the ACC and BATTERY connections in the head unit, so it's constantly getting power.

Could it be that?

Any suggestions would be dandy. Thanks.

 

[syphon123]

stupid question, but have u actually tried turning it on, cuz you have to do it manually, the stereo won't come on at all when the ignition is switched on, u have to physically turn it on urself.

if you have, then ill have a bit more of a think, cuz it could be a duff headunit. Have you got another car you can try it in?

joe

 

[Howard]

stupid question, but have u actually tried turning it on, cuz you have to do it manually, the stereo won't come on at all when the ignition is switched on, u have to physically turn it on urself.

if you have, then ill have a bit more of a think, cuz it could be a duff headunit. Have you got another car you can try it in?

joe

Yes, I'm not quite that stupid. I tried it with the ignition on, pressing and holding practically every button on the front of the unit, etc.

I don't hvae any other cars I can try it in. I hope it's not duff

 

[arc]

check the wiring matches up, check the cable colours.

check that the pioneer is getting power on the cables its meant to. it might look std ISO but its not always wired exactly the same

im assuming you've checked the head units fuse

 

[Liam]

Many of the high end head unit's today i.e. 4x50w and above need a direct power feed from the battery which holds an in-line fuse.

This part will sound silly bu if there is a yellow bullet connector and also a red one, plug the yellow into the red and vice versa and try that.

Liam

 

[chaos]

How many wires are in the car?
According to the owner's manual, there should be 6 wires, but when I went to install my JVC, there were 7!
Anyway, the 7th wire seemed to be an ignition wire or something, as it was bodged into the same connector as the power wire defined in the handbook.
Basically, I connected the power wires (the ignition wire off the headunit to this 7th wire, and the 2 main power wires together).
Tried to turn it on - nothing. Swapped the two leads over, which is what I think Liam was suggesting; still nothing :bang:.
I then realised that the 2 wires were connected together when I first took the old tape player out. So I removed the insulation caps off the bullet connectors, wrapped electrical tape around the 2 connectors so that the metal bits were touching, powered it up and it worked!

If anyone doesn't understand what I'm on about, I can stick up some pictures that I took of the whole process (I was practising with my digital camera) and I'll try to explain it better.

 

[Howard]

Yeah I've tried reversing the red and yellow bullet connectors

I've also tested the unit's fuse. It's fine

Chaos, if you could post pics that'd be cool. I don't quite understand

 

[Liam]

Looking at the manual for that model it says the black wire which came with the HU must be earthed to the vehicle body, I take it you have done this?

It does also say that the yellow cable must be connected to a constant source of 12v dc. The Cinq has now ignition switch relating to the HU meaning you can use it without keys, some people have wired the power to the cig lighter or electric windows as these need the keys.

Did you have a green display Philips HU with removable code panel previous? When removed did you have one black connector and one white? and an ariel?

I've heard of many Cinq's being wired for other radios with ISO connectors and the wiring ends up a mess.

Liam

 

[Howard]

Liam, thanks for all the suggestions.

It was a Philips unit with a green display and the keypad was removable, but the two ISO connectors are black and brown, and they were connected to what looks like the car's original plugs.
And yes it had the old-style aerial socket, but my dad reckons he'll be able to find and adaptor no-problem. That's not urgent to me anyway because I rarely listen to the radio


I'm not actually sure if the black earth wire is connected to the chassis

My dad is gonna check out the wiring with me tomorrow morning, and he reckons he'll be able to tell me whether or not the head unit is knackered


Thanks

 

[paul_treg]

Hi,
Most head units won't power up if there isn't a good earth/negative, best thing to do is connect the earth/negative to the chassis of the radio as well as the negative wire(possibly black wire), there should be an M6 threaded stud on the rear of the radio case use this to provide a good contact.

Also on the cinq there is an adapter from the main loom to the iso connector, make sure there are no bad connections at this point.

Fiats standard wiring has no ignition switched power, just a constant supply from the battery, so the yellow and red wire from the head unit will need to be connected to this single wire(can't remember what colour it is).

Hope this helps

Paul T

 

[chaos]

Right, I'll stick some pics up later (I'm on my friend's PC at the moment).
What I did was follow the wiring of the old radio to the letter. This extra wire that was installed in my Cinq enabled the headunit to be powered without the key in the ignition.
Is there a wiring diagram on your old radio? If there is, you could use that with your pioneer's wiring diagram and piece it all together.

 

[Howard]

I believe I might have figured it out

I went out with a multimeter today to check the voltages on all the wires, etc. Connected to the 12V and ground leads on the stereo harness... No voltage. "Whisky Tango Foxtrot" I thought.

This would co-incide with my dad's theory that there isn't a ground.

I plugged in the old radio without the aerial to ensure it all still worked (!) and it didn't turn on. Nada.
Plugged in the aerial and it worked!

Turns out it's getting the ground from the aerial lead to the car's chassis and no the cables!
Sigh!

I'm glad now. Just gotta try out my new head unit once we've fixed that and hopefully everything should be dandy. Fingers crossed. Lol

 

[Liam]

So the earth is completed by plugging in the aerial then, wonder how this will affect the new HU as it has a seperate earth wire according to the instructions.

Finally getting somewhere Howard its crap having no tunes.

Liam

 

[Howard]

Well once my dad and I get our hands on it tomorrow, with any luck the earth won't be going through the aerial lead anymore

Thanks for all your help folks

 

[arc]

i had something like this when i fitted a new HU into my step mums metro (eww)

confused the hell out of me! the wiring was a total mess tho. i ended up stripping the whole lot out and re-running wires to the fuse box, the OEM wiring was in that much of a state