TR3 Horn question:
Horns do freeze up, and, sometimes, they can be fixed. Horns are nothing more
than a buzzer with a diaphram. for
those of you who don't know how a buzzer works, let me explain. A buzzer
consists of a magnetically operated switch
and an electromagnet. The switch is wired in series with the electromagnet
coil. Current flows through the switch into
the coil, creating a magnetic field which opens the switch. This causes the
field to collapse, closing the switch, at
which time the field is again built up, opening the switch, which collapses
the field, closing the switch, etc, etc, etc.
This happens very rapidly, producing a buzzing sound. By placing a diaphram
on the switch, the sound is magnified
and the tone improved.
There are three types of failures with horns: 1) the contacts corrode
together, preventing the switch from opening, 2)
corrosion builds up on the contacts, preventing current flow through the
coil, and 3) the coil wire breaks.
By drilling out the rivets, you can get to the contacts to clean them. It
will be self evident what needs to be done. the
success rate for this repair is fairly good. If the coil wire is broken, it
can be fixed, but finding someone who knows how
to do it is very unlikely, and probably very expensive.
TR6 Horn question:
There are two possibilities with TR6 horns - either you have a horn relay, or
you don't. Triumps came both ways. I'll
cover both possibilities.
With relay: if you have a relay, the purple/black wire from the horn switch
will go to one of the "W" contacts on the
relay (the "W" contacts are W1 and W2). The other "W" contact will have a
purple wire on it. The relay will have two
"C" contacts, C1 and C2. (if the relay has been replaced by the DPO, it may
have a third "C" contact, C4. if so, it
should be empty, so ignore it). One of the "C" contacts will have a purple
wire on it. The other will have a purple/yellow
wire. The purple/yellow wire goes to the positive terminal on the horn. The
negative terminal of the horn will have a
black wire, which goes to ground.
Without relay: if you do not have a relay, the purple/black wire from the
horn switch will go out to the negative terminal
on the horn. The positive terminal of the horn will have a purple wire on it.
By the way, ALL purple wires in all triumphs
are hot at all times, whether the car is running or not and whether or not
the key switch is on.
Testing horns: they are very simple to test - connect the negative terminal
of the horn to the ground terminal of your
battery, and connect the positive terminal of the horn to the positive
terminal of your battery. If the horn is good, it will
sound, if not, it won't.
Hope this helps. Contact me if you need more input.
Dan Masters
|