by Terry Boyd
To be honest there is no art to fitting car radios,
but there are rules and laws to be upheld. Not that you'd
find them stuck on Rumpole of the Bailey's bookshelf;
these laws are unwritten ones - that is until now. The
first rule that I would try to emphasize is to read the
fitting instructions before you attempt anything. I have
been caught out many times, myself, by assuming that,
just because I have been fitting these things for
numerous years, then I am exempt and therefore perfect.
It's as if the manufacturers know this and deliberately
bring out something different each year to try to catch
me out. Modern cars tend to have "line-fit radios". This
means that they are manufactured with the radio wires in
the wiring loom as standard, so that Fred on the end of
the production line can just open up a box and insert it
into the hole. This is all very well and commendable, but
(don't ask me why) when Mr Angry buys this vehicle, all
he can think about is taking out the radio, that was
fitted neatly and designed to work with the speakers that
are also so neatly and expertly hidden, and putting in
something that looks and lights up like a Christmas tree.
Then he proceeds to cut enormous holes into the back
parcel shelf, where he fits speakers, that could have
been used at Glastonbury Festival, and a sub woofer in
the boot so that he can not only damage his own eardrums
but anyone else's within two hundred yards. This is where
we come in because, like him or not, Mr Angry wants to
spend lots of money with us to get the job done right
[I'm sure he doesn't really but, as he can't do the
job himself, he's got to pay somebody else - and why
shouldn't that be us?]
I've already mentioned that line-fit radios tend to be
the ones that most punters want to change and, to make
this job easy for us, there are adaptor looms that have
been manufactured by some clever little entrepreneur
especially so that we can have an easy life. These can be
bought for £10.00 or less from car accessory shops.
Unfortunately, in my experience, Mr Angry has already
tried to fit it himself and decided to cut all the plugs
off first then, by joining any colour that he thinks fit
to any other colour wire that takes his fancy at the
time, he blows his interior lights fuse, accessory fuse
and then decides to bring it to me to be put right and
picked up in thirty minutes, (or so he would like to
think).
As mentioned in the previous article, I use a tool
called a Power Probe and this tells me what electrical
state a wire is in at any one time. The first thing that
you are looking for is a permanent live. If you are lucky
enough to find one then my advice would be to put some
insulation tape over it before you are unlucky enough to
short it out to an earth and blow another fuse. If you
can't find a permanent live then Mr Angry has already
blown the fuse for you. This you can forget about for a
while. The next wire to find is the switched live. Now
some cars need the ignition switch turned to the
auxiliary position and some cars need the switch in the
full ignition position, so that the "twit" lights are all
on. Hopefully you will be able to find one that lights
your probe (as the actress said to the vicar). I digress,
now back to the plot. If it lights up then stick some
insulation tape around it so that you can locate it when
you need it. Next turn on the lights, after putting the
ignition switch back to the off position, and look for
another live. This will be the instrument illumination
supply so that, when the side lights are turned on, the
radio front lights up to be visible in the dark. If you
don't find one, don't be too disappointed as not every
car has one. There will normally be a thick wire, brown
in most cars, but not in all. This is the earth wire, and
it's probably not a bad idea to mark this as well.
Next to the speakers; my most used gadget after my
Power Probe is so simple it's frightening. It's a PP3
battery with a connector on it with wires. This toy is
used to ascertain which of the remaining wires are
speaker wires and which position they occupy in the car
ie. front or rear, left or right. There is no easier way
to do than to choose one speaker wire, place one of the
wires from the PP3 battery on it and, in turn, touch the
other wires until you hear a scratching noise coming from
one of the speakers. When you have ascertained which
direction the noise is coming from, make a note of the
two wires, either by labelling them, or by writing their
colours down on a piece of paper. Eventually you should
end up with four pairs of wires consisting of two front,
and two rear sets of speakers. Should you have any wires
left after doing this you can safely assume that one of
them is the permanent live that you couldn't find before
and one of them will be for the electric aerial. Although
the car that you are working on may not have what you
presume to be an electric aerial, most modern cars have
an amplifier built into the roof or wing , or back or
front window aerial. This amplifier requires a feed from
the radio to activate it and will give very poor
reception if left off. (I have seen this done many times
and, when you put the supply back on for the customer, he
can be very grateful indeed and promise to bring all his
work to you in future).
The next job is to find why your permanent live is
dead; this isn't as difficult as it may sound, as all you
need to do is find the master fuse box. In saying that,
the fuse box isn't always the easiest thing to find but,
working on the premise that all cars have got one,
eventually you'll find it. Once you have found it then
it's just a simple case of looking for the fuse that's
blown, and replacing it for one of the same type. Go now
back to your loom and hopefully you will now have a
permanent live, so for heavens sake cover the end with
your insulation tape again, or else it'll touch what it
did before and blow again!
Now we come to the dilemma of how best to connect the
new radio to the existing loom. If you have a radio with
bullet connectors already fitted to the ends by the
manufacturer, then the easiest way is to put bullet
connectors on the loom. Remember to make sure that they
are crimped on correctly, as per last months article.
There is only one more thing to do and that is to make
sure that the permanent live and switched live are the
right way round. This won't stop the radio from working,
but it will mean that the radio won't be coming back to
you in two days time because it can't remember the
stations, which your customer has just spent hours
putting in. If, however, there are no bullet connectors
on the radio, then the best way to connect is either with
butt end connectors or preferably with solder and
shrink-wrap insulation. Please do not use "chocolate
block" screw terminal strips as they can allow wires to
pull out.
Hopefully that may have whetted your appetite for
doing this type of work, especially when Mr Nasty has
opened his wallet to pay you, because it's normally about
this time that his wayward son, Walter Bodger, comes
along and asks you to fit his 500 watt amplifier into his
Vauxhall Cavalier. Before you attempt this type of job,
you need to take a little time to work out where things
are going to go and to plan it carefully. This is what
will make the difference between a professional job and
one done by Walter.
Firstly, you need to measure the size of the unit that
you will be fitting and look for an appropriate sized
position where it will fit without standing out like a
sore thumb.
Secondly, determine if it will be safe if fitted there
(and I don't mean will somebody steal it, I mean, that
amplifiers can get very hot and they can burn the
upholstery, or carpet, or discolour the paintwork).
Thirdly, think: "How am I going to attach it to the
vehicle. Will it be with screws and, if so, where can I
drill the holes for them?"
Fourthly, is there going to be enough space to get the
extra wiring in safely, remembering that the bigger the
amp, the thicker the cable and, therefore, it will be
harder to bend to make a neat fitting.
Point 5: (I don't like saying fifthly), where is the
12volt feed coming from, allowing for the heavy current
that the amp may need to work?
Point 6: Have I got enough of the correct size of
cable, both for the feed and the speakers? It is
important that you have the right size cable for the
speakers as well because the thinner it is, the worse the
frequency response will be and, also, the speakers will
not work as efficiently as they are designed to do, as it
won't pass enough peak current.
Point 7: Have I allowed for the wire for the remote
connection on the amp coming from the radio?
Point 8: Is there a convenient space for a good earth
connection near to the amp?
Once you have weighed up all these things, then, and
only then, are you ready to start fitting the unit. Do
remember that the larger the amp the hotter it will run
and therefore will need fitting to a good heat sink. The
boot metalwork or underneath the rear metal parcel shelf,
as long as it isn't a removable one. I have a lot of
young lads bringing me their amps for repair. Most of
them are brand new, and the lads can't face taking them
back to the shop where they bought them as they're
embarrassed that the shop won't give them either their
money back, or an exchange unit, because they've blown it
up themselves by incorrect fitting. I very rarely ever
find anything wrong with these amps, other than they are
lacking the remote connection from the car radio electric
aerial wire, to the terminal labelled "remote" on the
amp. Most people don't realise that an amplifier,
although connected permanently to the battery of the
vehicle, is designed to work only when the radio is
switched on, and it does this by recognising another 12v
feed going directly to the "remote" connection on the
amp. This feed is present only when the radio is switched
on. It comes from the electric aerial output on the radio
or from the wire designed for this purpose and marked
accordingly.
Once I had a rather spotty Herbert arrange to bring
his car around because he said he had a fault with his
radio which kept blowing fuses. In addition, the sound
out of his speakers was awful. Before I removed his radio
from the car I asked him to show me what was wrong. He
proceeded to put a tape into the cassette and turn the
volume up; the most awful sound came out of the speakers
and I realised, in seconds, just before the fuse blew,
what the problem was. He had a large amplifier connected
to speakers that were obviously too small for it and both
the radio and the amp, were being fed from the same live,
overloaded, 12 volt feed. After a slight difference of
opinion between ourselves he began to see my point, about
fitting it correctly, and agreed to let me do it for him.
Many pounds later after I had put in a proper feed and
replaced his rear speakers with higher rated ones, he
left - still the same spotty Herbert but a poorer and
wiser one and, probably, a deafer one by now!