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Cap'n · 04-02-2008, 01:01 PM

A good searching nets me a lot of threads about the phsyical installation of Givi racks, and I put them to great use. Got the topcase rack mounted last night in about 45 minutes with no issues whatsoever. Well, no phsyical issues.

I got the 52 liter topcase with integrated brake lights (and E21's for the sides). The instructions say, basically, "find the bike's tail light hot wire, use this little clip, and attach it to the case's hot wire. Then do the same with the ground wire." Thank you, Copernicus, how enlightening. I was once a residential / commerical electrician, so making connections and sorting out wiring diagrams in my head isn't a big deal, but I didn't work on DC.

The tail light has 3 wires: Black, Blue, and Yellow. The black goes to the outside of the lamp socket, which tells me it's the ground, no? That leaves the blue and the yellow, one for the running light fillament, the other for the braking filament. And on the flipside, the topcase has 2 wires, one black and one blue. So the final result should be "running = stock tail light, braking = stock brake light + case lights come on." Yes? So I'd need to figure out which of the blue and the yellow are which. But then there's the other wrinkle: Which wire is which on the topcase? They disappear into the lights, and aren't marked on the outside anyway. But they're single filament bulbs, so if they're like AC, it really won't matter - current goes through a filament and then grounds.

So I made the assumption first that they should be paired up, black to black, and blue to blue. I popped on the connectors, clicked on the topcase, fired the bike up, and got this:

Running: Tail light normal, topcase lights on.
Front brake: NO DIFFERENCE.
Rear brake: Tail light brighter, top case lights still on.

...

So I disconnected the topcase wires entirely and re-tried the bike, disturbed about the front brakes not tripping anything. SAME Result - no response from the tail light to the front brake, but normal response to the pedal. I took it around the street in front of the house, thinking (wishing) it had something to do with movement or speed, and it doesn't. My grizzled old Harley riding buddy tells me this used to be the norm, where the front brake didn't trip the light, but the back brake did.

Thoughts? You guys have always been very helpful - appreciation in advance.

04-02-2008, 01:01 PM	#1 (permalink)
Cap'n Superbike Racer Join Date: Apr 2007 Location: Cambridge, MA Age: 33 Posts: 239 Casino Cash: $2528 Sportbike: 2007 Yamaha FZ6	Givi Topcase Electrical Question A good searching nets me a lot of threads about the phsyical installation of Givi racks, and I put them to great use. Got the topcase rack mounted last night in about 45 minutes with no issues whatsoever. Well, no phsyical issues. I got the 52 liter topcase with integrated brake lights (and E21's for the sides). The instructions say, basically, "find the bike's tail light hot wire, use this little clip, and attach it to the case's hot wire. Then do the same with the ground wire." Thank you, Copernicus, how enlightening. I was once a residential / commerical electrician, so making connections and sorting out wiring diagrams in my head isn't a big deal, but I didn't work on DC. The tail light has 3 wires: Black, Blue, and Yellow. The black goes to the outside of the lamp socket, which tells me it's the ground, no? That leaves the blue and the yellow, one for the running light fillament, the other for the braking filament. And on the flipside, the topcase has 2 wires, one black and one blue. So the final result should be "running = stock tail light, braking = stock brake light + case lights come on." Yes? So I'd need to figure out which of the blue and the yellow are which. But then there's the other wrinkle: Which wire is which on the topcase? They disappear into the lights, and aren't marked on the outside anyway. But they're single filament bulbs, so if they're like AC, it really won't matter - current goes through a filament and then grounds. So I made the assumption first that they should be paired up, black to black, and blue to blue. I popped on the connectors, clicked on the topcase, fired the bike up, and got this: Running: Tail light normal, topcase lights on. Front brake: NO DIFFERENCE. Rear brake: Tail light brighter, top case lights still on. ... So I disconnected the topcase wires entirely and re-tried the bike, disturbed about the front brakes not tripping anything. SAME Result - no response from the tail light to the front brake, but normal response to the pedal. I took it around the street in front of the house, thinking (wishing) it had something to do with movement or speed, and it doesn't. My grizzled old Harley riding buddy tells me this used to be the norm, where the front brake didn't trip the light, but the back brake did. Thoughts? You guys have always been very helpful - appreciation in advance. Last edited by Cap'n : 04-02-2008 at 01:04 PM.