Hello all, could someone please draw me a schematic of how to add a brake relay to my 1990 bagger. I have burned out several switches and think its time. One question, if installed will it also protect the rear switch. I have a red and a orange wire going to front switch, will be mounting in fairing.

Thank you, Rick

 

It'd be better to find out why you're burning switches. Sounds like a wiring problem, and it will only get worse. Adding a relay will only delay the inevitable.

 

As stated above, even without the relay, you should not be burning the switches. In this application, the relay is to minimize the voltage drop thru the wiring and ignition switch, not the protect the switches. I installed one on my 90 ultra just to minimize the voltage drop, but I never had a problem with the switches prior to installing the relay.

 

+1 on the above suggestions.

Could be corroded connector... and are you certain they are actually going bad? Reason for asking, they are very tempermental about having the switch housing aligned with the lever/mastercylinder bracket in a way as to not put it in a bind. Just a thought because front brake switches generally don't give that kind of trouble.

There is an anti-dive valve for the front end that is electrically part of that circuit. It's easy for the tabs at the solenioid switch to get bent/mashed around when working near them. Might be a spot worth looking at ...

I can draw up a simple diagram but really, I'd make sure all the connection points are good and no shorts in the wires before adding more wiring.

 

You wouldn't be towing a trailer, would you? Shouldn't be burning out switches, unless you're drawing excess amperage.

 

I've had my 1990 FLHS from new and agree with the others here. You have an electrical problem which needs sorting, otherwise you will burn out the relay!

If you install a relay you will need to use the wiring which currently operates the brake switch to operate the relay. So you will still have a problem.

 

Could there be a short on the brake wiring that runs to rear tail light.
Do not know about that year but on many others the wiring runs under rear fender.
Not too far fetched to have been cut/bent/shorted by tire or frame movement.
and as mentioned above a relay would only delay the problem.
last: have you added a whole load of lights to that circuit?

 

thanks for all the input. I will start at the back and work to the front. It makes sense that somewhere I am shorting to ground. And the p.o. did have a trailer wiring kit, but I took that off. Would I be better off starting in the handlebar control. Reason for asking is if I hold the red and orange wire together, brake lights come on fine. What if I put a 20 fuse inline with the orange wire and than held them together. If it doesent blow the fuse would that indicate its an issue in the handlebar wiring and if it does blow, start checking connections?

thanks for your help, Rick

 

that could be a possible option..or maybe a circuit breaker..several in auto parts for a few $(less than $10 in fuse section) and would save the hassle of continued replacement while diagnosis takes place.
Does that year of bike have a relay under the seat for brake lights??? if you did you would hear a click each time rear lamp lights with engine off.
I would start at the location the trailer wires tapped the system.

 

thanks again for the input. The p.o. also had extra brake lights added and I am wondering if that is too much draw for the switches to handle, thats why I am considering adding the relay. Also the rear switch is affected in the same way. Just wondering, when you apply the brakes and hold your brake light on, what does you voltmeter show. Mine hits 10 volts or so. Is that too low, and does that indicate a short possibly. I have the seat off now and have found a loose red lead that goes into the cruise control unit. The cruise control works when it wants to. It will always give me the red indicator on dash, but will mostly not engage. Number one reason is usually a bad bulb or connection at a bulb. I think I am starting to answer my own questions. Well back to the garage. thanks everyone