From: Mrcheerful on
Ben Short wrote:
> "Duncan Wood" <nntpnews(a)> wrote in message
> news:op.vapm6um6haghkf(a)
>> On Tue, 06 Apr 2010 00:03:53 +0200, Ben Short <bshort(a)>
>> wrote:
>>> No 13 fuse specifically, which is a 20amp fuse for the 12 lighter
>>> sockets.
>>> Well the problem is it keeps going. I used the lighter socket to
>>> power a TomTom and it went. So the garage put another one in and I
>>> came to use the TT again and it wouldn't charge it, then upon
>>> inspection I see its blown the fuse again.
>>> I am going to take it to the Corner Garage but wonder if anyone here
>>> could shed any light on what may be wrong. We don't use the
>>> cigarette lighter at all, we don't smoke. It gets used for the Tom
>>> Tom VERY occasionally, perhaps twice a year.
>>> There is no rust on the end of the socket although there is a tiny
>>> little bit on the side wall of the socket, none on the lighter plug
>>> itself.
>>> Thanks
>> Are you sure the charging lead for the tomtom's the correct polarity?
> Hi Duncan
> It is the plug that came with it. I had no idea there were different
> types to be honest. How do I find out

There is a convention that the centre pin is positive, unless the lead has
been changed or the socket rewired it is very unlikely that either are the
wrong way round. Try your accessory in another car, if it works ok in that
then you know the lead is the right way round. Get a new fuse in the car
and test the socket with a multimeter, the sides of the socket should be
neutral and the centre contact positive. If the fuse blows while plugging
in the accessory then it is very likely that the plug is a poor fit in the
socket and is shorting out somehow as you push the plug in.