Hands free car kit not powering up

[Dr Zoidberg]

A couple of weeks ago I bought a Sony Ericssson car kit from someone I
know.
First time I connected it up it worked for 10 minutes then when I turned the
car off and restarted it - nothing.

Thinking I might have pulled a wire loose somehow I removed the whole thing
and retested it and it's been refusing to play nicely ever since.

To power it , there are three wires - Black for earth - Red for permanent
12v and Blue for ignition sense that needs to be connected to a switched 12v
supply.

I reconnected the power wires to the fuse box (once fuse for switched 12v
and another for permanent 12v plus a handy earth) and checked that I was
getting the correct voltages at the connector where it goes into the car
kit.

Plugged it together , switched on the ignition and nothing happened - no
signs of life. Rechecked everything - definitely getting 12v at the
connector where it goes into the car kit but it won't work.

I removed it all as I'd run out of time and then tried again a couple of
days later with the same results. Thinking this was very odd I got my
multimeter out again and measured the volatage that I was getting at the
fuse with it connected to the car kit , and with the ignition off I was
getting 12v. If I turned the ignition on so that the ingition sense has a
12v feed but didn't start the engine , the voltage on both switched and
permanent 12v lines dropped to just 5v. When I started the engine the
voltage went back up to 12v and everything started working. I've fitted a
fair few stereos in the past and never seen anything like this before - I
can't understand why the voltage should drop that much.

I didn't have time to finish off so once again I disconnected everything and
I've just come back to look at it today. I've reconnected to the fusebox and
checked that I have the correct voltages where the cable plugs into the car
kit - all good.
This is wired exactly as it was last time , but now it won't power up at all
with the engine running or not. Thinking I may be going mad I've connected
the permanent and switched 12v wires directly to the 12v feed going into the
back of the fusebox - nothing. I definitely have the power going into it but
there's no life.

That would suggest that the car kit is faulty , but just wanting to confirm
things I popped the bonnet and connected it directly to the battery and it
works just fine.
Back to the fusebox - no life , back to the battery direct - working.

Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

[SteveH]

Post by Dr Zoidberg
Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

It's that dodgy Czech build quality.

Should have bought a proper VW rather than a cheap Commie copy ;-)

[Ged]

Has it got a decent earth?

[Dr Zoidberg]

Post by Ged
Has it got a decent earth?

Yes.

[Ged]

On Aug 11, 4:30 pm, "Dr Zoidberg"

Post by Dr Zoidberg

Post by Ged
Has it got a decent earth?

Yes.
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

What year is the vehicle? If its a newer model it might have CAN/VAN/
Multiplex wiring. Some ignition feeds will drop out and do funny
things under very little current draw.

[Dr Zoidberg]

Post by Ged
On Aug 11, 4:30 pm, "Dr Zoidberg"

Post by Dr Zoidberg

Post by Ged
Has it got a decent earth?

Yes.
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

What year is the vehicle? If its a newer model it might have CAN/VAN/
Multiplex wiring. Some ignition feeds will drop out and do funny
things under very little current draw.

It's an 06 octavia and it does have CAN-Bus wiring

[Ged]

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit? If you are I would
probably try running a feed from the barrel or lighter socket (if its
12v ign), pick a nice think wire. The ones at the head unit and other
locations are probably linked into the CAN bus stuff. I don't really
understand CAN bus but I know it does some funky stuff when you try
tapping anything onto it, any current draw can cause problems.

[Ged]

Post by Ged
12v ign), pick a nice think wire. The ones at the head unit and other

....not sure what a think wire is...probably best to try a thick
wire:)

[Dr Zoidberg]

Post by Ged

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals

[Ged]

Post by Dr Zoidberg
Nope , into the fuse box onto a couple of spare terminals
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Hmmm, I would try going onto the back of the barrel or lighter.....it
would rule out any problems on the ignition at least.

[moray]

Post by Dr Zoidberg

Post by Ged

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals

With it being CAN Bus, the fuse box most likely isn't just a fuse box. It'll
have a CAN controller built in, and chances are you've probably picked up
two fuses that are controlled by the CAN controller for optional extras.
Hence the strange goings on with voltages.

Professional installers will always take a feed direct from the battery, and
unless they can find a suitable ignition controlled wire, they'll wire the
kit up so it's permanently on. It just means you don't get the option of the
phone turning off with the ignition (most handsfree kits will work with the
igntion off anyway).

[Dr Zoidberg]

Post by moray

Post by Dr Zoidberg

Post by Ged

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals

With it being CAN Bus, the fuse box most likely isn't just a fuse
box. It'll have a CAN controller built in, and chances are you've
probably picked up two fuses that are controlled by the CAN
controller for optional extras.

The fuse that I've used for the switched live is labelled with a phone
symbol , suggesting it's designed for a car kit.
The other one I can't remember off the top of my head.

Post by moray
Hence the strange goings on with voltages.

Indeed.

Post by moray
Professional installers will always take a feed direct from the
battery, and unless they can find a suitable ignition controlled
wire, they'll wire the kit up so it's permanently on. It just means
you don't get the option of the phone turning off with the ignition
(most handsfree kits will work with the igntion off anyway).

I'd rather not have the continual drain , even if it is low.
Looks like I'll have to try and find a route through from the engine bay for
a permanent 12v though

[Ged]

I would personally take the feeds from the back of the barrel. Good
luck with it whichever route you go.

[Chris Bartram]

Post by Dr Zoidberg

Post by moray

Post by Dr Zoidberg

Post by Ged

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals

With it being CAN Bus, the fuse box most likely isn't just a fuse
box. It'll have a CAN controller built in, and chances are you've
probably picked up two fuses that are controlled by the CAN
controller for optional extras.

The fuse that I've used for the switched live is labelled with a phone
symbol , suggesting it's designed for a car kit.
The other one I can't remember off the top of my head.

Post by moray
Hence the strange goings on with voltages.

Indeed.

Post by moray
Professional installers will always take a feed direct from the
battery, and unless they can find a suitable ignition controlled
wire, they'll wire the kit up so it's permanently on. It just means
you don't get the option of the phone turning off with the ignition
(most handsfree kits will work with the igntion off anyway).

I'd rather not have the continual drain , even if it is low.
Looks like I'll have to try and find a route through from the engine bay for
a permanent 12v though

I didn't bother with the 12v switched when I last fitted a car kit- just
pggybacked it all off the fag lighter- and never had any problems.

[SteveH]

Post by Chris Bartram

Post by Dr Zoidberg
I'd rather not have the continual drain , even if it is low.
Looks like I'll have to try and find a route through from the engine bay for
a permanent 12v though

I didn't bother with the 12v switched when I last fitted a car kit- just
pggybacked it all off the fag lighter- and never had any problems.

Be careful - I had to call out the AA a couple of weeks ago - I have a
4-way adaptor in the centre cubby with sat-nav, phone and PDA chargers
plugged into it.

I parked the car up for 5 days or so, left everything plugged in, and
came back to a battery so flat, I couldn't start the car.

[moray]

Post by SteveH

Post by Chris Bartram

Post by Dr Zoidberg
I'd rather not have the continual drain , even if it is low.
Looks like I'll have to try and find a route through from the engine bay for
a permanent 12v though

I didn't bother with the 12v switched when I last fitted a car kit- just
pggybacked it all off the fag lighter- and never had any problems.

Be careful - I had to call out the AA a couple of weeks ago - I have a
4-way adaptor in the centre cubby with sat-nav, phone and PDA chargers
plugged into it.
I parked the car up for 5 days or so, left everything plugged in, and
came back to a battery so flat, I couldn't start the car.

Chargers that plug into a accessory socket generally remain active all the
time (ie. LEDs usually stay on) when plugged in, whereas proper phone kits
are designed to power down to minimum power if not being used.

[moray]

Post by Dr Zoidberg

Post by moray

Post by Dr Zoidberg

Post by Ged

Post by Dr Zoidberg
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex
"I laugh in the face of danger. Then I hide until it goes away"
www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals

With it being CAN Bus, the fuse box most likely isn't just a fuse
box. It'll have a CAN controller built in, and chances are you've
probably picked up two fuses that are controlled by the CAN
controller for optional extras.

The fuse that I've used for the switched live is labelled with a phone
symbol , suggesting it's designed for a car kit.
The other one I can't remember off the top of my head.

Post by moray
Hence the strange goings on with voltages.

Indeed.

Post by moray
Professional installers will always take a feed direct from the
battery, and unless they can find a suitable ignition controlled
wire, they'll wire the kit up so it's permanently on. It just means
you don't get the option of the phone turning off with the ignition
(most handsfree kits will work with the igntion off anyway).

I'd rather not have the continual drain , even if it is low.
Looks like I'll have to try and find a route through from the engine bay
for a permanent 12v though

The carkit will power itself down if there's no phone connected, so I
wouldn't worry about it.

[Chris Bartram]

Post by SteveH

Post by Dr Zoidberg
Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

It's that dodgy Czech build quality.
Should have bought a proper VW rather than a cheap Commie copy ;-)

Trying to wind us up again Steve ;-)

[SteveH]

Post by Chris Bartram

Post by SteveH

Post by Dr Zoidberg
Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

It's that dodgy Czech build quality.
Should have bought a proper VW rather than a cheap Commie copy ;-)

Trying to wind us up again Steve ;-)

I need new bait, Zoidberg appears to be immune to the stuff I'm using
;-)

[Dr Zoidberg]

Post by SteveH

Post by Chris Bartram

Post by SteveH

Post by Dr Zoidberg
Now this is a total mystery to me. It seems to vary from week to
week the situations in which it will and won't power up and I'm
checking all the connections with a multimeter and it *is* getting
power. Why should it be happy with 12v in one place and not in
another?

It's that dodgy Czech build quality.
Should have bought a proper VW rather than a cheap Commie copy ;-)

Trying to wind us up again Steve ;-)

I need new bait, Zoidberg appears to be immune to the stuff I'm using
;-)

It's fairly old and stinky , and normally Zoidy will eat anything!