Rear Brake Switch

[Guest]

The brake light doesn't come on when the rear brake is pressed, but it does when the front brake lever is.
I made some nicks into the wires leading to the taillight, and touched a circuit tester to the copper wires. The white wire is the front brake lever, and the brown one is the taillight. The solid black, black with white tracer, and green wire don't show a light on the tester (but I assume at least two of those are the blinkers).

Where is the rear brake switch proper?

 

[Guest]

Above and slightly behind the brake pedal. It's activated by a long (maybe 2 inch) spring.

 

[cowboyup3371]

That white wire is for BOTH brake levers to activate the light. there will be a junction near the air box for them to meet with one leg dropping down to the switch near the rear wheel.

Do you have the wiring diagram from Basscliff’s site?

 

[Guest]

That white wire is for BOTH brake levers to activate the light. there will be a junction near the air box for them to meet with one leg dropping down to the switch near the rear wheel.

Do you have the wiring diagram from Basscliff’s site?

There is no diagram for a 550. And if memory serves, many of the links lead to errors or missing content.

 

[Rich82GS750TZ]

there's a 550E service manual on BikeCliffs site. there's a wiring diagram near the back. Why go nicking wires? All the resources are here.

Cowboy's right. White wire.

Switch looks something like this. It clips into a bracket with a hole in it that is welded to the frame, directly above the Brake Pedal Pivot. The spring attaches to a hole in the part of the pivot that lives inside of the frame close to the swingarm. When the spring is pulled by pressing the brake pedal, it activates the brake light. Adjust the sensitivity of the switch by turning the black plastic nut, moving the switch further or closer to the pedal, putting more or less tension on the spring. You want the brake light to come on as soon as you apply any pressure to the pedal.

 

[Gorminrider]

If you can't find a diagram for your exact bike, look at another one. Almost all these bikes of the 80s have the same brake light set-up and wire colours...

test the above for good continuity of course...it's merely OFF/On Spinning the metal end a few times can improve contact but a new one is best.

 

[Guest]

there's a 550E service manual on BikeCliffs site. there's a wiring diagram near the back. Why go nicking wires? All the resources are here.

Cowboy's right. White wire.

Switch looks something like this. It clips into a bracket with a hole in it that is welded to the frame, directly above the Brake Pedal Pivot. The spring attaches to a hole in the part of the pivot that lives inside of the frame close to the swingarm. When the spring is pulled by pressing the brake pedal, it activates the brake light. Adjust the sensitivity of the switch by turning the black plastic nut, moving the switch further or closer to the pedal, putting more or less tension on the spring. You want the brake light to come on as soon as you apply any pressure to the pedal.

Thanks for that, that's more specific. I was looking for anything with a spring, but didn't see, but I was sweeping the general area, not looking closely.
As for nicking wires, they're easily repaired, and how else am I supposed to test for power flow through them if they're all bound in a wiring harness? I wanted to make sure power was flowing downstream properly, so relatively close to the taillight is where I cut (under the passenger seat). I also hadn't found the switch at that point.

 

[cowboyup3371]

There is no diagram for a 550. And if memory serves, many of the links lead to errors or missing content.

It's in the service manual you should have downloaded when you were doing the previous work - http://zeus.mtsac.edu/~cliff/storage/gs/GS550_77-82_all.pdf

 

[Guest]

It's in the service manual you should have downloaded when you were doing the previous work - http://zeus.mtsac.edu/~cliff/storage/gs/GS550_77-82_all.pdf

I have the service manual. However, the low-quality black and white picture doesn't do my eyes any favors, and doesn't show my exactly where the switch is. I found it tucked behind the frame, hidden in a cowling. I found it by looking for the spring, then following that.

 

[Rich82GS750TZ]

ZPS,
If by cowling, you mean the plastic side covers, I don't know why they'd be on the bike if you're working on / inspecting the wiring around the battery. As to poking holes in the wiring: There are no connections inside the wiring harness. Every wire terminates at either a bullet connector, terminal inside of a plastic block, or is soldered or screwed into a switch, circuit board, or light bulb fixture. At any of these points you can check continuity at each end of every wire without poking holes. You may have to remove some electrical tape or push back a rubber boot here and there. You should be cleaning any connector you come across, just as a matter of course. If all you have is a test light, get a voltmeter. They're dirt cheap at Harbor Freight.

IMHO, If you find the manuals and wiring diagrams on BikeCliff's site inadequate, I suggest you look for a factory service manual on ebay, or at least a Clymer or Haynes Manual for your model. A good service manual is the most important part you can buy right now. I understand money is tight. But I've found the Clymer Manual to be an indispensable tool in diagnosing problems and setting things right.

 

[Guest]

ZPS,
If by cowling, you mean the plastic side covers, I don't know why they'd be on the bike if you're working on / inspecting the wiring around the battery. As to poking holes in the wiring: There are no connections inside the wiring harness. Every wire terminates at either a bullet connector, terminal inside of a plastic block, or is soldered or screwed into a switch, circuit board, or light bulb fixture. At any of these points you can check continuity at each end of every wire without poking holes. You may have to remove some electrical tape or push back a rubber boot here and there. You should be cleaning any connector you come across, just as a matter of course. If all you have is a test light, get a voltmeter. They're dirt cheap at Harbor Freight.

IMHO, If you find the manuals and wiring diagrams on BikeCliff's site inadequate, I suggest you look for a factory service manual on ebay, or at least a Clymer or Haynes Manual for your model. A good service manual is the most important part you can buy right now. I understand money is tight. But I've found the Clymer Manual to be an indispensable tool in diagnosing problems and setting things right.

More like a rubber sleeve.
And I have both a test light and a voltmeter, but that may be on the fritz.

 

[Guest]

Just for information, you don't Need to have both brake switches working by law, as long as one works it's fine

 

[Rich82GS750TZ]

Just for information, you don't Need to have both brake switches working by law, as long as one works it's fine

Maybe that depends on the state. In PA, this line is form the motorcycle inspection page of PennDOT:

The stop lamps shall be operated through a switching arrangement so that any motion of brake towards applied position immediately illuminates the stop lamp

To me that means, whenever you apply brakes, whether front or rear, your brake light must light up.

Legality aside, there's the safety issue. Case-in-point: - When you're stopped on the road because you're making a left hand turn but have to wait for on-coming traffic to clear, left foot down, right foot on the brake, You want the cars coming up behind you to see your brake light. Happens every day on a 55 mph road in front of my house. Or if I'm sitting at redlight. I don't want to grab the front brake lever. I'd rather rest my right foot on the brake pedal. May need my right hand to flip up my visor, or whatever. I need the people coming up behind me to see if i'm slowing or stopped.