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1984 R65 Turn signal switch and horn not working

jbcoyle

New member
Hi,
I'm new to the MOA, and new to BMW. I just bought an '84 R65, and on my first long ride, the turn signals and horn stopped working about midway into a 4 hour ride (luckily I remembered my hand signals). So, my research is pretty limited on the possible causes. Since both the horn and the switch is not working, I thought there might be a ground problem. I'd be interested in anyone's opinion on the matter. Everything else works, high beams, headlight, starter, etc.

Thanks, I tried searching, but maybe I'm not looking in the right place.
 
Welcome to the forum! Other than the lights/horn, how's the bike?? I'd check the fuse...it seems that the horn and turn signals get power from the same fuse. The ground points will likely be different for these, so I'm not thinking ground is the issue. Not sure where the fuses are...on some of the earlier bikes, it's in the headlight shell. Could be on the '84, the fuses are relocated somewhere, maybe under the seat or battery side panels? Hopefully someone will have a better location for the fuses.
 
The bike is really fun... Just one more note, it appears that the brake light is also not working. Maybe it is all the same fuse.
 
I think so...the brake light power seems to be closely connected to power for the horn. I would be looking at fuses.
 
Fuses

On your R65 the fuses (two of them) are in a little black box at the rear of the frame back bone, on the bottom. There is a thumb screw on the cover that holds it on. Occasionally there will be a bit of corrosion build up on the fuse and fuse mount so if the fuse looks good, you might want to scuff of any corosion that might be present.
 
So, I replaced the fuse, and 10 minutes into my ride, it blew again. Conditions were; stopped at a light, turn signal flashing and hand brake engaged. I had used the brakes and the turn signals before that point in time... Any ideas?
 
Well, it's clear you have some kind of short. What you need to do is come up with a setup which allows you to clip to each side of the fuse block and have these two wires/clips connect to a small light bulb, like something in a flashlight. That way, the bulb won't go out but will burn brightly when the short situation is encountered. You'll need to move wires around and/or operate the turn signals and hand brake successively until the bulb indicates you've found a short. It will have to be a process of elimination until you find the exact wire that is causing the problem.
 
And I'm guessing that is done with the engine running? So I guess the light bulb acts as the fuse? I don't put a fuse in there, right? And it should be a filament bulb, I guess.
 
Check with your owner's manual but I think both fuses should be 8A. The blown one looks like a smaller type fuse.

/Guenther
 
When I bought the bike it did not come with a manual. I found one online, but I don't know if it is for a 1984 R65. The manual I found online says that the fuses must not be greater than 8A. The fuse I bought at the auto parts store was an 8A fuse (at least that was what they told me). I agree that the other one looks much heavier. I guess that may be a bigger problem, unless there are different types of 8A fuses. Looking in various places for 8A fuses online, this is what they all seem to look like:
8AMP.jpg
 
The type of metal that the fuse is made of will determine the thickness of the metal where it is supposed to burn out. I have a supply of fuses enough to last through the next millenium, but the last time I bought fuses they were color codes with white corresponding to 8 amp.
 
Right, and the one I put in was white, and looked like the one in the image. However, I can't help but think that there may be characteristics (like slow-blow) that may be relevant, and that might be the difference between the different metals. I still can't believe that that circuit could possibly draw 8 amps without a short. There is the flasher, the turn signals, the horn, and the brake light and brake light relay. I'm going to pursue the light bulb testing...
 
Right! 8 amps is plenty for the designed load. So consider an intermittent short. Concentrate on what is causing the fuse to burn out and not the aspect of slow burn fuses. Basic electrical troubleshooting procedure will narrow down the area.
 
So, I have jerry-rigged the light bulb and inserted it in place of the fuse. I've tried to operate the electrics both with the engine on and the engine off. With the engine off, I have a battery charger that I put on the battery. I've observed some interesting things:
- the brake light comes on when I depress the rear brake. It does not come on when I press the front brake. Should the brake light turn on when using the front brake?
- the horn does not work at all, although to be fair, I never tested the horn when I bought the bike.
- the turn signal doesn't work at all. When I had the engine off, I could hear a buzzing from the turn signal flasher when I turned the switch on. If there was a short in the turn signal switch or wiring, would the buzzing be expected? Or is the buzzing an indicator of a bad flasher? I believe the flasher is under the gas tank,. Is it easy to take the tank off?

Thanks in advance for any tips to resolve this.
 
Yes, the front brake switch is supposed to operate the brake light. Also, there is a power connection between the front brake switch and the horn. So, as long as the horn ground is good, you must not be getting any power to the horn. You can certainly check that with a voltmeter. With ignition on and engine not started, I believe there should be 12v on one side of the horn terminals. Touch your negative lead on the voltmeter to ground and then probe the terminals on the horn. One of the terminals should be 12v. The horn works when you push the horn button...you complete the path to ground.

I'd see if you can clear up those two things and then see where you are.
 
Verfiied that 12-ish volts is on one side of the horn. I did not chesk the other side of the horn. When I press the horn button, the fuse light shines very bright.

Also I need to figure out where the wire is for the front brake... Found it, and the wires were not connected. So I connected them, and now the brake light works when the lever is pressed, however, still no trun signals and no horn...
 
Remove the horn and apply 12v across the terminals from a standalone battery. Ensure that the horn even works.
 
Back to basics.

Ok. So let's start with where the power is coming from and where it goes.
You say that you don't know if the horn really works or not. Here is how to test it. There should be two wires going to the horn. Use the test light to see if you have power to the horn by turning on the ignition and testing each wire with your test light. I don't have a wiring diagram in front of me but if it is like a /5 then you have a green/black wire and a black wire. It doesn't matter because we're just testing to see if you have power to the horn. If neither wire lights up the test light then you do not have power to the horn! If one wire lights up then connect it to the horn and ground the other connector on the horn. There may be a slight buzz holding the horn or the horn may sound off. This will tell you if the horn works or would work if adjusted correctly. You're closing a circuit. If you use the test light instead of the horn in the circuit and press the horn button then if the light comes on you have a bad horn. Same thing with the front brake light switch. If you have power to the switch then wire in the test light on the other terminal and go to ground with it. Apply the front brake. No light means a bad switch. If you don't have power to the switch then trace back to see where the open circuit is.
If you have a relay that just buzzes then it could be weak/bad or there isn't enough voltage static, to make the relay work. Sometimes with a low battery and a weak relay, there isn't enough voltage to make the relay perform.
 
Unfortunately, I'm away from home this weekend, so I can't work on the bike. I put my voltmeter on the horn, and verified that there was 12.2V on the one side. I was going to try to make the horn work by powering it separately, I think the horn will work. I thought it was odd that there was a very large current draw when I pressed the horn switch. The light that I have jumping the fuse was really bright. So I'm beginning to think there is a short somewhere in the left handlebar. I'll get back to it on Sunday night.

I'm also curious about the buzzing of the flasher relay. There seems to be plenty of life in the battery, so maybe I have a bad flasher...

Thanks for your advice.
 
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