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FatHead1979

12v permanent live options for head unit

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Hi all,

After the car went smoothly through it's MOT (after it had a front wheel bearing replaced, that I knew needed doing) I though I was good to go.  This morning the car had other ideas, the car drives fine but there is no power to the aftermarket Sony head unit that has been fitted for around 3 years. :wallbash:  I've tested the various sections of wiring from the head unit back to the car side of the quad lock and the wiring is good (I used the front courtesy light wiring to to power my 'tests').  I also put connecting blocks on the wiring before the quadlock and this also worked perfectly so we can rule out the quadlock itself as being the culprit.  The issue seems to be that there's no power being supplied to either the permanent live or the 'switched' supply (at least in terms of the loom that is for the head unit).  I've checked all the fuses in the footwell GEM and all look good.

Does anyone have any bright ideas? (the GEM is dry, no signs of water ingress etc).  If I can't find the culprit and fix it I'll have to look at tapping into a different feed but it'll need to be permanently on rather than switched.

When I carbon wrapped a few bits previously I'm sure I found a spare loom on the passenger side (I assumed it was for electric seats, if so does anyone know if the feed for the electric seats in permanent live or if not what other options I have in terms of tapping into a permanent live?).  Does anyone know if the 'cig lighter' in permanent live?

Thanks in advance for any bright suggestions.

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Have you checked the fuses under the bonnet too?

I'm not entirely sure how accurate the schematics are for the 2005 Focus compared to the mk 2.5, but the permanent battery live for the radio comes directly from the battery, through a fuse in the EJB, into the PJB, through a fuse there and directly to the radio.

The Ignition sense connection comes from the EJB, through the ignition barrel, through the PJB and fuse, and then to the radio.

Does your instrument cluster light up correctly on turning the key?

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Everything works as it should apart from the 2 positive feeds in the loom behind the head unit.  Will check the external box tomorrow.

Cheers

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Used a piggy back fuse to run from the 20 amp cig lighter (always on) up through the centre console to the head unit, now everything works again.  When pushing the unit back the unit kept flicking on and off but was fine once back in place, I suspect that there is at least 1 broken wire in the loom but it is somewhere in the section that is is hidden so I'll live with it!

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