Wiring in a horn relay...

[billwill]

Original wiring looms used thicker wire, I think, so the heavier loading worked?

Replacement looms have thinner wire. The thinner wire is used on modern cars as they have many more wires, but also more relays.

[l10tus]

Phil.H,

Sorry, didn't mean to hijack your thread, but Bill's and other replies, were really helpful I thought?

(Thanks, I'll give it a go as recommended.)

Hope you sort your Horn issue out !

Regards,

Phil.T.

[oldchieft]

Right, now add in the Air Horns !

Anybody suggest a wiring diagram for both sets of horns, so as to sound at the same time (as original?)

I can only get either or to work ( both with relays)

Any ideas, because that's got to be the follow-on to this thread!

Regards,

Phil.

I had a set up on a Morgan were the electric horn worked off the original switch and another push button operated both horns.

(The electric ones always sounds first as the is no compressor to run up to speed. So it give a quick response followed by a loud blast.)

I will try to remember/work out how I did it. I think it might be by cascading two relays.

Jon the Chief

Ok, checked it out, and as suspected it was a cascade set up.

Take a feed from the input side of the fuse box brown wire, put in a inline fuse holder.

Mount an extra horn push and feed it from your new fuse holder, take the output from the new push to the coil of a relay, the other side of the coil earthed.

Feed the COM side of the relay from the new line fuse, take the N.O. side of the relay to the air compressor.

That is the normal set up for extra air horns.

To make the original horns work from the new horn push.

Take a daisy chain wire from the COM terminal of the first relay to the COM terminal on the second relay, take a daisy chain wire from the N.O. output of the first relay to the coil of the second relay, the other side of the coil to earth.

Take a the N.O. from the second relay and feed the original horns at any convenient point in the wiring, but best taken all the way to the horns.

This way the two systems are separated by two open switches, the original horn push and the open relay.

Jon the Chief.

[pharriso]

OK Chaps the weekend is here so managed to install the relay:

I bought a nice small 30a relay off eBay, was originally going to use a more date correct 6RA but too big! Here's it installed:

The relay is mounted on the bracket

Here you can see how I interrupted the purple/black wire that goes to the horn push & then rewrapped the loom:

& most important of all it works as designed!

[pharriso]

Finalized wiring diagram:

[gjz30075]

Phil, does this nullify the first diagram you posted?

[pharriso]

Phil, does this nullify the first diagram you posted?

I just added a few labels & added the table with relay terminal designations. No functional changes at all!

[oldchieft]

Right, now add in the Air Horns !

Anybody suggest a wiring diagram for both sets of horns, so as to sound at the same time (as original?)

I can only get either or to work ( both with relays)

Any ideas, because that's got to be the follow-on to this thread!

Regards,

Phil.

I had a set up on a Morgan were the electric horn worked off the original switch and another push button operated both horns.

(The electric ones always sounds first as the is no compressor to run up to speed. So it give a quick response followed by a loud blast.)

I will try to remember/work out how I did it. I think it might be by cascading two relays.

Jon the Chief

Ok, checked it out, and as suspected it was a cascade set up.

Take a feed from the input side of the fuse box brown wire, put in a inline fuse holder.

Mount an extra horn push and feed it from your new fuse holder, take the output from the new push to the coil of a relay, the other side of the coil earthed.

Feed the COM side of the relay from the new line fuse, take the N.O. side of the relay to the air compressor.

That is the normal set up for extra air horns.

To make the original horns work from the new horn push.

Take a daisy chain wire from the COM terminal of the first relay to the COM terminal on the second relay, take a daisy chain wire from the N.O. output of the first relay to the coil of the second relay, the other side of the coil to earth.

Take a the N.O. from the second relay and feed the original horns at any convenient point in the wiring, but best taken all the way to the horns.

This way the two systems are separated by two open switches, the original horn push and the open relay.

Jon the Chief.

I forgot the Lotus runs the horn wiring back to the steering column then earths it.

To make the original horns work from the new horn push.

Take a wire from the purple and black side of the electric horn to the COM terminal on the second relay, take a wire from the N.O. output of the second relay to earth.

Take a daisy chain wire the N.O. of the first relay and feed the coil of the second relay, other side of the coil to earth.

This should work for Column earth systems.

Jon the Chief