horn relay

[twist]

Hello every one! I'm in the midst of installing an S fairing to my 77 R100 and using a RT bracket modified to mount the fairing to the frame. While I'm at it I wanted to address several other issues; install several relays, one of which is for the horn. While I consider myself competent to handle most tasks I am stumped by the simple relay. I seem to be hooking it up wrong because the damn horn won't work hooked up the way I have it. I must have something wrong but I think I have everything connected the way it is in the diagram. I understand electrics a bit and apparently enough to do it wrong.

[Kurt in S.A.]

I can't get to the Airheads side which explains the relays. But my Haynes shows a different connection for the horn relay on a '77 R100RS.

- 30 -- power
- 87 -- to horns and then to ground
- 85 -- frame ground (not through the horn switch, though)

That's all the same. But there's no connection between 30 and 86 plus:

- 86 -- connects to handlebar horn button

The way I understand it is that 85 and 86 are the lower power side and when that circuit is closed, it closes the internal relay contacts to let power flow from 30 to 87.

Not sure that helps...

Kurt in S.A.

[twist]

thanks, I'll give that a try. Simple thing like this making me grumpy.

[ME 109]

thanks, I'll give that a try. Simple thing like this making me grumpy.

It's only going to get worse Twist.
A horn delay will really piss you off.
Apparently.

[Rob Frankham]

There are four ways for a horn to be connected via a relay...which you use will depend on the way your button is wired (this differs from model to model) and the horn you have. Not sure which applies to the '77 R100. If the horn has two terminals, it can be used in any of the setups below… if it has only one, it will ground through the fixing bolt and you will have to use either setup 1 or setup 2. If the horn button is connected to positive, then setup 2 or setup 3 can be used. The connections are as follows

Setup 1) ... 1) Relay terminal 30 to battery + (via a fuse)
2) Relay terminal 87 to Horn +
3) Relay terminal 86 to switched battery positive (Green/Black on a boxer)
4) Relay terminal 85 to Horn button
5) Horn Button to ground
6) Horn - terminal to ground

Setup 2) ... 1) Relay terminal 30 to battery + (via a fuse)
2) Relay terminal 87 to Horn +
3) Relay terminal 85 to ground
4) Relay terminal 86 to Horn button
5) Horn Button to switched battery positive (Green/Black on boxer)
6) Horn - terminal to ground

Setup 3) ... 1) Relay terminal 30 to Horn -
2) Relay terminal 87 to ground
3) Relay terminal 85 to ground
4) Relay terminal 86 to Horn button
5) Horn Button to switched battery positive (Green/Black on boxer)
6) Horn + terminal to battery + (via a fuse)

Setup 4) ... 1) Relay terminal 30 to Horn -
2) Relay terminal 87 to ground
3) Relay terminal 86 to switched battery positive (Green/Black on a boxer)
4) Relay terminal 85 to Horn button
5) Horn Button to ground
6) Horn + terminal to battery + (via a fuse)

Incidentally, the setup shown on the card will work for a horn with one terminal grounded but the problem is it will work all of the time… whether the ignition is on or off. Not a good way of doing it!

Hope that helps

Rob

[twist]

thank you, Rob! Very much appreciated since this will speed things up some and a delay of installing the relay could get ugly! I'm also installing LED turn signals and know I need resisters to make them work properly. I mentioned this to my brother in law who is an engineer for CAT and his opinion on using resisters for the turn signals is good but a better way is to use a voltage regulator. This rewiring has taken on a life of it's own.

[She'llbe]

Hello every one! I'm in the midst of installing an S fairing to my 77 R100 and using a RT bracket modified to mount the fairing to the frame. While I'm at it I wanted to address several other issues; install several relays, one of which is for the horn. While I consider myself competent to handle most tasks I am stumped by the simple relay. I seem to be hooking it up wrong because the damn horn won't work hooked up the way I have it. I must have something wrong but I think I have everything connected the way it is in the diagram. I understand electrics a bit and apparently enough to do it wrong.

Have you got any photos/drawings/measurements for that bracket mod?