Okay, So i bought a new head unit for my MK3 Polo

Plugs directly into the existing ISO connectors as it should.

Only problem is the stereo will not turn on, but i know it has power as you can load and eject cd's into the unit, and when you press the reset on the unit, it makes eject sounds etc...

Can anyone help me out here?

After a bit of googleing people say it is likely to be:

1) A weak power feed?

2) Faulty Ignition Live?

3) A bad earth?

Anyone had similar issue? How would i go about solving this problem?

Any help much appreciated.

Edited 5 June, 201412 yr by Pionion

where is the head units ign on wire attached to

alot of players will accept the disc with just the 12v attached ...i suspect you have no ign on wire

where is the head units ign on wire attached to

alot of players will accept the disc with just the 12v attached ...i suspect you have no ign on wire

well i have compared the Iso connector on the head unit- To the car Iso connector (Digram against diagram) and all the correct wires match up.

But i haven't tried tracing the wire back behind the dash as yet, Can i ask where it should be connected up?

(I can't check until this evening until i am home from work - But would like to know where to start looking when i get home)

Again, assistance is much appreciated.

Edited 5 June, 201412 yr by Pionion

well not 100% sure for a mk2f ....BUT mk2 and most other vw that age dont have the ign on wire on the car side

So i have perhaps two options?

1) Run both the Stereo side Ign live & Constant live straight to the car Constant live?

2) Wire in a seperate power feed from the back of the ignition?

yes thats right ...assuming what i say is correct for the mk2f

I will try connecting both sides on the stereo directly to the constant live on the car, and see if that works...

Am i correct in assuming as long as the head unit is switched off/Faceplate removed it should not drain the battery?

There is a version of an Ignition supply, it's called the "S" contact, that supplies 12v as soon as the key is put in the ignition, this is the thin Brown/Red wire going to pin 4 of the original radio, the 12v live battery supply is the thick Red/Grey wire via fuse # 11 8amp, the "S" supply is not fused it comes direct from the ignition switch

also some head units need the ign and live swapping at the plug

There is a version of an Ignition supply, it's called the "S" contact, that supplies 12v as soon as the key is put in the ignition, this is the thin Brown/Red wire going to pin 4 of the original radio, the 12v live battery supply is the thick Red/Grey wire via fuse # 11 8amp, the "S" supply is not fused it comes direct from the ignition switch

Yeah, I currently have the stereo "ignition live" wired to the "S" supply as mentioned but it isn't working, After speaking to the supplier of the head unit's technical team, they say that often because this "s" supply isn't fused it can be blown and thus rendered dead.

also some head units need the ign and live swapping at the plug

The stereo has two switchable leads on it which allow you to cater for this, and in one position there is no power at all, and the other is the current situation, thus evident power but no illumination.

My plan is to try and wire both the stereo's power feeds to the car's constant live, as the technical support team agreed with steveo3002 that it is more than likely the ign live is not working from the car correctly.

I Will update you of my findings tonight!

Cheers again for your help :)

The "S" contact is fed directly from the battery supply to the ignition switch, so if it's not supplying 12v it will either be the contacts in the switch have failed or the wire from it to the radio is broken

The "S" contact is fed directly from the battery supply to the ignition switch, so if it's not supplying 12v it will either be the contacts in the switch have failed or the wire from it to the radio is broken

So just to clarify in my own mind, the "S" supply goes as follows

Battery > Ignition switch > Stereo...

That's correct, a feed from the battery goes direct to the ignition switch (unfused) and that's fed out via the "S" contacts as soon as the key is in the ignition and at all other positions except start

Just a little update, I know my stereo works as when putting Stereo Ign Live + Constant live to the car Constant live everything works

So it means the car ign live is not working for whatever reason, so my intention is to wire in a new one.

Cheers for the help guys!