Harley Brake Switch Diagnosis

Hi, I'm Bob LaRosa. Welcome to "Fix My Hog." As you can hear, it's raining outside real heavy, so obviously, we're not gonna be doing much riding. It is an ideal time to do a little electric troubleshooting. I get questions all the time pertaining to electrical issues. First note I wanna make, and I do stress this all the time. Resource material is invaluable. When it comes to troubleshooting, whether it's a dead short or an intermittent electrical problem, you need to have a resource. Wiring diagrams, service manuals, owner's manuals. Haynes, Chilton, Clymer are a manual manufacturer conglomerate. They cover a broad range of automobile and motorcycle manuals. They are founded in 1960, and they have a passion for the industry. Anything they set their sights on creating a good, thorough manual for is thoroughly researched and diagnosed before it goes into print. The manuals themselves are almost 500 deep in the US to cover a broad spectrum of automobile. There's almost 200 motorcycle and ATV manuals alone. These manuals come in year-, model-, and make-specific. They do have a full color wire diagram section. And again, when it comes to a good, thorough resource, Haynes manuals are hard to beat. They give the do-it-yourselfer the opportunity to do it yourself. When it comes to electrical troubleshooting, I have the Softail on the lift. Problem is an inherent problem with this motorcycle, the rear brake light stays on constantly. Now obviously, it's not functioning correctly and it is unsafe. I mean, I would prefer a brake light on all the time as opposed to not having a brake light at all, but it doesn't change the fact that it's not functioning correctly. And again, with the heavy rain we're experiencing today, it's the ideal time to take some time, diagnose, and troubleshoot why the brake light stays constantly illuminated. As you can see, I've taken for demonstration purposes, I've taken the harness out of the loom so you can see the individual wires that create the circuit from the main harness to the handlebar switch. There is a brake light switch here located behind the lever. There's also a rear brake light switch located beneath the transmission clutch cover. On a Softail, this brake light switch is actuated by the rear brake pedal. All right? When I know I have a brake light that's constantly illuminated, first place I head to is the rear brake light switch. And I just take a moment and unplug it. By unplugging the rear brake light switch, if the fault lies in the rear brake light circuit or switch, the rear brake light should no longer remain illuminated. Obviously, when I unplugged it, it's still lit, so that leads me to either the main harness, which covers the rear fender, the backbone of the frame, or the short section of the harness to the handlebars. Or the problem may lie in the handlebar switch itself. When it comes to testing electric troubleshooting, electrical issues, whether they are constant or intermittent, my favorite tool of the trade is a standard test light. Yes, once you get deeper into the whole electric troubleshooting, you will need a voltmeter, you will need to monitor constant voltage or voltage drops, but when it comes to let's call it on-the-road troubleshooting, troubleshooting you're able to carry the tool in a tool pouch and figure out a problem on the fly or if someone's broke down that you're riding with, at least you can make a temporary fix, do a quick diagnosis, and get back to a point where you can repair the motorcycle correctly. The test light itself, you always have to verify that it's working. Put it on the negative of the battery, always on the negative, don't trust the chassis, and test it to the positive side of the battery. All right, with the ignition switch off, you can still see the test light's illuminated. Obviously, I'm directly at the power source, the battery. I can do a quick test for input power to the rear brake light switch. I'll take both tabs off. Turn the ignition switch on. Again, always verify your test light's working correctly. After verifying the test light works, I can now probe into the two wires from the rear brake light switch. With the ignition switch on, I can see that they are powered. Again, that's quick troubleshooting, you're just trying to find a power source if it exists. The best way to go about any type of electrical tracing or troubleshooting is to refer to your Haynes manual, get to the correct model, year-specific, and reference their color-coded wiring diagram. You can clearly see they're marked, right hand controls. And if you look deep into the diagram itself, you'll locate the rear brake light switch and the color of wire that you're working with. Another note I wanna make, typically, wiring harnesses, electrical components don't just fail. There is an underlying cause as to why a component doesn't work correctly. Yes, voltage regulators do get old, They overheat, they stop regulating and rectifying correctly. But for the most part, our main harness on a motorcycle, when left untouched, should remain working correctly indefinitely. So when it comes to troubleshooting, the first thing I wanna do is look around the motorcycle and see if anything's been changed. Has there been an upgrade to handlebar controls? Have brake lever, clutch levers been recently replaced? Has there been a custom add-on? First thing I always look at is their scotch locks. Scotch locks, although they function very well for a quick connection, on a motorcycle, when they're subjected to vibration, have a tendency to create intermittent connections. That's why I prefer to strip wires, twist 'em, solder 'em, heat shrink 'em. You've seen those processes before. Again, I like to always do a good, thorough overview. 8 out of 10 times, you'll find your problem because it's the last area on the motorcycle that might've been touched, whether it be for a custom application, somebody added on a new light and just scotch-locked it in, or they put a hand levers on and happened to disturb the front brake light switch in the handlebar control housing. Again, refer to wiring diagrams. Always make yourself familiar with the particular circuit that the problem lies within. Because the brake light is stuck on all the time, doesn't necessarily mean you have a problem with the starter circuit or the charging circuit. At this point, you have a problem with the lighting circuit. And bear in mind, the lighting circuit can be split into different configurations, headlamp, turn signals, tail lamp. Don't take for granted because the headlight's on, the brake lights should be working. It may be fed from a different power source, depending on your make and model. As you can see, there's a number of wires that lead up to the right-side handlebar control housing. You need to refer to the manual, chase down the two wires that are gonna feed the brake light switch. In this case, it is the red with the yellow tracer and the orange with the white tracer. So you can always probe around. See if you have constant power with the ignition switch on. Always make sure, the motorcycle has to be in the operating state that the light is functioning in or illuminated in. And it's as simple as probing around. Do you have power going to the switch? Do you have power exiting the switch? And for the most part, due to the fact that the brake light is constantly on, I see I have power entering and exiting the control on the right side of the handlebar. It shouldn't be that way. It's telling you that it's constantly illuminated. Even with the rear brake light unplugged entirely, you'll see power in and out to the brake light switch on the right side is still constant, it's as if the switch doesn't exist. Now again, common sense plays a big role, whether it's regular maintenance, whether it's service, whether it's electrical troubleshooting, common sense plays a big, big role. Know what you're troubleshooting, don't just start probing around. Chances are you can cause more damage than good if you're not probing on the right side of the connector or even in the right circuit path. This is telling me that this switch is either not even existent or that it's not working correctly. So what I'll typically do is look up in the switch housing, locate the end of the switch, and just carefully actuate the switch manually. You can see by relieving the pressure on the switch, the brake light is no longer illuminated. What's that's telling me is I'm manually functioning the switches if you're pulling in and out on the brake light switch. And again, if you happen to find out the owner just installed a brake lever kit, chances are either the housing isn't sandwiched together or the lever itself wasn't correctly installed and broke the switch. A lot of times, it's as simple as loosening up the housing. I'm just getting everything to sandwich back together correctly. Re-tighten the housing just by loosening the switch housing and correctly aligning the brake lever to the brake light switch. You can see I have correct brake light function. Again, electrical troubleshooting, always start with the basics and let the troubleshooting get you more and more involved in the wiring itself. Always start with the basics. Don't go to level C or level D when all you really need to do is a quick adjustment at level A. I just wanna take a minute and show you with the test light. This is the brake circuit, the orange and white, the orange wire with the white tracer and the red wire with the yellow tracer. With the ignition switch on, the orange wire is constant feed, but yet now the red wire with the yellow tracer is no longer illuminated, where before, when the tail lamp was illuminated all the time with the ignition switch on, the orange wire was hot, as it's known, or powered, and so was the red wire with the yellow tracer. Now the red wire, which tells me it's a return wire from the switch out into the harness to the brake lamp is no longer illuminated through the test light constant, but if I actuate the brake lever, I can see my power flow through the harness, through the switch, through the harness, through the test light, and correctly illuminating the brake light. So for the most part, when it comes to electrical troubleshooting, if you have a bulb that's out, don't start by tearing the motorcycle apart, chasing down wires. Again, start with the simple and let the troubleshooting get you to the more difficult. The rear brake lamp, if it wasn't illuminated at all, I certainly wouldn't start by troubleshooting a switch. I would pull the tail lamp lens and check the bulb. Bulbs are serviceable wear items. A heavy impact can break a filament in a bulb. If you happen to have tail lamp working but not brake lamp, chances are it may just be the bulb. If you lose both tail lamp and brake lamp, it may be a fuse, but don't take for granted because a fuse popped or blew that all you need to do is put a new fuse in. An underlying issue caused the fuse to overload and pop or blow. Fuse is a different story. You need to find the end result that caused the fuse to blow. This circuit obviously was working correctly. It was just illuminated constantly. By adjusting the handlebar switch so the switch is back in the picture, you did electrical troubleshooting with the Haynes manual, the color wiring diagram, track down where the issue lied, addressed it, and corrected the problem. I've been doing electrical troubleshooting for years. I find that a colored wiring diagram is invaluable. Not only does it give you isolated circuits in color, but the Haynes manual itself is so thorough that the wire colors are correctly matched to the make and model you're working on. You can see they're clearly marked, right hand control, stoplight switch. The orange and white is the feed in. The red and yellow comes out. And as you follow the red and yellow wire, the number 12, you flip the page, you pick up your number 12, same red and yellow wire. You can see it leads to the tail lamp and it also splits and goes to the rear stoplight switch. Again, wiring diagrams are invaluable. 90% of my troubleshooting comes from the wiring diagram before I even get to the motorcycle. I try to solve the problem before I take anything apart. And again, I can't reiterate enough, when it comes to electrical issues, look for the underlying cause. Is a bulb bad? Was a custom modification done incorrectly? Was a wiring harness rerouted incorrectly and worn through or chafed or heated by a hot component? Take your time, make sure there's adequate time to troubleshoot. Electricity can be funny, but it also can be fun.