Fiamm horn/relay question.

[RideSolo]

Thank you very much for all the responses. I appreciate all the brain effort that was expended and it's somewhat gratifying that I'm not the only one looking and head scratching. The bike had been sitting since '88 or '89 and of course the battery was nothing more than an paper weight. I hooked 12v up to it and had lights and horn before I started disassembly so I know that whatever was on there did work. There aren't any unidentified wires hanging nearby. I did see that there is a scotch connector in the headlight bucket that I need to go back to and try to identify its purpose. One of the wires out of it runs to the small bulb (parking light?) at the bottom of the headlight. Thanks again.

[srankin]

You know I haven't asked a simple question and the answer might shed some light how to proceed. The relay you have on hand, does it have the internal wiring diagram stamped on the case or printed?

If it does, can you take a good picture and attach it so we can look at it?

I am asking for the reason of determining if the relay needs to be grounded to work? Did the previous owner have it bolted to the frame or was it just wrapped up in a mess of wire and tape hanging freely?

I may be wrong in assuming but I think the overall draw of the two horns was less than 8 amps or a fuse would have blown. Of course, the previous owner could have tied into a non fused power source but your mentioning him using the parking light makes me wonder if he drew total power from that source. This kind of defeats the purpose of a relay as the parking light circuit is not designed for higher current draw than to like the taillight and parking light bulbs. I have to wrap my head around why he would tie into that circuit.

By all means, try to figure out what he had tied into and get back to us. I have an idea as to wire things up using stock wiring without perhaps the use of dreaded scotch locks. LOL, when done, you may well have a neat tidy hook up. Then again, LOL I have been wrong. St.

[RideSolo]

Again, thank you for all the responses.

I'm almost at a point where I can reconnect the battery. When that happens the horn mess is one of the first things I'll tackle. AND I'll post what comes about. I certainly hope the DPO didn't bodge up the wiring in the headlight bucket to give constant power to the + side of the horn circuit.

[srankin]

Despite the inside of the headlight shell sometimes looking like a bundle of jumping snakes, unless the PO, spliced on wire to existing factory wires, everything is pretty well sorted,

All the stock wiring is pretty well color coded, Solid color wire is usually a hot unstitched or uncontrolled, unfused, Positive source, Solid brown is always a ground.

The main circuit board is color coded and is mostly divided into two parts. One side is the input side of the two fuses, the other is output.

In your case, trace the wire harness coming from the horn button side into the shell and look for the brown white striped wire and the solid brown wire. They should be plugged into the pins in the proper color coded section of the board.

One thing you should purchase if you haven't got is a good wiring diagram. The best I have found are available at EME, they are color, and not only have the color wires but the PIN numbers for wire connectors as well. Stock relays and such have PIN numbers stamped or printed on them to designate what color wire plugs into what pin.

I have to admit, I don't have a diagram of this type for your bike, only the Cylmer manual one. LOL, maybe if I did have one for your bike I would see a good place to plug things in and make them work.

I admit, this is most likely a very simple thing to hook up and I really don't know why I am making it so difficult. Well, I do know why, LOL, As I wrote, I don't like adding things to the stock wiring or changing the stock wiring and I like neat tidy wiring. I guess I am too fussy. St.

[srankin]

Any luck? St.

[RideSolo]

Thanx for asking.

I haven't messed w/ it yet. I got pulled in a different direction and it now starts and runs; first time in about 35 years(!). When I put the tank in place the relay interfered w/ it so I had to relocate and haven't gotten back to get that all tied up. I'll get at it in a couple days.

[RideSolo]

Sorry it took me so ling to get back to this. I messed around a bit w/ the relay the way I thought it had been hooked up in the past, couldn't get the horn to work. I tested voltage at the existing horn wires and get ~12v when I press the horn button. A couple of clip leads from the battery to the horns themselves gives a nice, healthy beep. Hooked the horn button wires directly to the horns and a button push results in a blown fuse. (99.9% sure I didn't do something stupid like reversing polarity when I did that, but I only had one extra fuse so I've got to get more before I try again.) I'll try messing around w/ the relay itself to see what I can get from it: 12v in and see if it'll switch as is should. Any more suggestions?

[srankin]

I never asked but in the original bundle of wires you cleaned up, was there wires going direct to the battery from the relay?
Or perhaps a wire from the B post on the relay to a tap into a Red wire in the wiring harness?

At the horn, you should get 12V. Positive power is the Green/black wire, with the Brown/yellow wire as grounded through the horn button where when making contact pressing the button brown wire becomes ground.

As for blowing the fuse, it is likely the current load to fire two horns versus one on the circuit exceeded the amperage rating of the fuse. This is why in the newer bikes with two horns a relay was added. The high current needed to blow the horns is supplied by the black wire coming from the horn relay in the newer bikes.

The issue I am having with hooking up your relay is that IT is set up to use a switch that has positive current flowing whereas your switch is only a ground completer.

In all honesty, I think you are going to have to use the Green/black wire at the single horn and attach it to the S position on your relay. Then you will have to run appropriate wire gauge wire to the battery positive side and attach it to the B point of the relay. Or tap that post by wire into a red wire in the wiring harness. The H point of the relay will of course go to the horns.

St.

[RideSolo]

No power directly from the battery, none from a + wire, that's why I was so confused when I started working w/ the thing to get it hooked back up. Somehow the only wires hooked to the relay were the two from the switch and one from the horns. And, yes, put a volt meter across the wiring harness leads from the switch and there's 12v when the button is pushed.

Yes, I believe you are correct. I had pretty much decided I was going to power up the relay w/ some test leads, make sure it's working and then see if I can't come up w/ a way to make it work. As I said in my first post, the thing WAS working and it's completely my fault for not taking good notice of how it was all hooked up when I pulled it apart. I should have noticed that the whole horn/relay installation was so unBMW, it never occurred to me, but should have, that it would be some kind of voodoo arrangement. (At least I was very careful to note, bag, and label everything else when I disassembled and it's now running and almost ready to ride.) Worse comes to worse I'll either just hook up one of the two horns or I'll finds a nice single horn to throw on there and be done w/ it. (I've always likes those little air horns!)

[srankin]

Voodoo, LoL never underestimate a previous owner for creativity.

Let me just get this straight, you have checked the Brown/white striped wire and the brown wire for the switch and got power?

OKAY I can kind of figure out how that is happening, is the horn in the circuit? See, the power is coming from the Green/black wire (positive) through the horn, out (not the best way to put it but like water flow) the brown/white wire (which is a ground but a switched ground). Pushing the button, completes the flow of current to a brown Frame grounded wire.

If you look at pulling the horn out of the system, there should be no current to supply 12V.

Just for giggles and to prove me right or wrong, try the voltage check with the Green/black wire off the horn and check for voltage at the brown/white terminal on the circuit board and a brown wire. LOL, if you get 12 volts, I think I will have to bow out of this as I clearly am wrong.

In my last answer, I gave you the path to hook up your relay to use two horns. The high amperage feed line will either have to run directly to the positive side of the battery or, you can tap into a red wire, or if there is an extra red wire terminal on the circuit board, you can plug in there.

This has been interesting.

Then again, stock style single horns are on the market for not a lot of money.

Air horns would land you back into the same issue you have with the dual horns. How to hook up a relay. St.