> 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 (if the relay has been replaced by the DPO, it may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
Thanks for the very clear explanation!
While assessing the Wiring Diagram for my '70 TR6 in the
Repair Operation Manual, it became very clear as I fliped
back and forth between the USA Up to End of "71 model (no
horn switch) and the USA From Introduction of "72 model
(has horn switch) that my '70 has a switch! I am assuming
DPO installed the switch, possibly when put in a later year
harness or the replacement horns????
The relay I have has the 5 switches, with C1 (switch at
front left of box towards the front of the car) being wired
with original wiring, as well as W2 (furthest back switch on
box toward rear of engine bay). The "juiced" switch W2 is
connected directly to the replacement horns, with the horns
grounded to a bolt. What is interesting in relation to your
description is that the remaining two switches, C2 and C3 are
connected together by a wire (not part of original wiring, just
a jump wire). There is one Purple wire (not totally sure sine
I need to remove the paint to get a clear read on the wire colour)
not attached, which I assume was left free to accomodate the new
The horns, which are Lucas, have double switches on each side
(positive and negative connections), something like this
= = (sorry for the graphics, the O represents the center screw).
The wiring was still on although the horns were not operational
due to the replacement horns. Obviously, only one switch on both
has the female connector attached with the other bare. On the low
tone (right)horn it is the back switches connected and on the High
tone (left) horn it is the front switches.
Haven't tested the horns yet to see if they work, but would be
interested in your thoughts on this set up.