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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: WoahGold on August 07, 2012, 10:26:54 PM

Title: Rear Light Problems
Post by: WoahGold on August 07, 2012, 10:26:54 PM: I've had a bit of an ongoing problem that's getting progressively worse. Every now and then I lose all lights in the rear (brake, license plate, etc) and the BMU light would come on. Then I'd ride a bit more and they'd come back.

I've checked bulbs, contacts, fuses and I'm not really sure where to got from here.
Before I ever have a chance to go in with a multimeter and really dig they come back on.
Has anybody else had this happen and/or know where a good place to start would be? I'd really appreciate it.

Here it is not working, notice the headlight and lights on the cluster are on.
(http://i1059.photobucket.com/albums/t433/WoahGold/0168e05a.jpg)

Then I moved it 40 ft. to the guest parking because I have family coming to visit tomorrow and they come back on.
(http://i1059.photobucket.com/albums/t433/WoahGold/6cda6e3e.jpg)

I have a sneaking suspicion that it has something to do with whatever this black box is.
(http://i1059.photobucket.com/albums/t433/WoahGold/cf77f885.jpg)
Title: Re: Rear Light Problems
Post by: Motorandy123 on August 09, 2012, 01:18:06 PM: That box is not stock. Was someone trying to make running lights out of the blinkers possibly?
I'd trace down those wires an remove the box if possible. There should be like 4 wires going to
the back of the bike...
Title: Re: Rear Light Problems
Post by: frankenduck on August 09, 2012, 01:19:56 PM: If both the tail and brake lights quit working at the same time then the first thing I'd suspect is a bad ground.
Title: Re: Rear Light Problems
Post by: Motorandy123 on August 09, 2012, 02:52:17 PM: All the grounds are up on the neck of the bike under the tank. I suppose the
brown wire running to the back could somehow be bad. You can see a brown
wire on the box. Maybe check that wire to ground on the bike?
Title: Re: Rear Light Problems
Post by: argent brick on August 09, 2012, 03:34:28 PM: Look at all that room in the rear cowling! Man, sometimes I wish I did not have ABS.
Title: Re: Rear Light Problems
Post by: Opus on August 09, 2012, 04:16:54 PM: I'm with The Duck on this one. Check the ground wires 1st.
If that box has a part # you can google it to see what it is.
Title: Re: Rear Light Problems
Post by: mystic red on August 09, 2012, 09:04:13 PM: Quote from: frankenduck on August 09, 2012, 01:19:56 PM
If both the tail and brake lights quit working at the same time then the first thing I'd suspect is a bad ground.

Or a dirty starter Duck? :dunno
Title: Re: Rear Light Problems
Post by: WoahGold on August 09, 2012, 09:45:57 PM: Randy - Someone DID make running lights out of the blinkers, I figured it was stock.

Thanks everyone, I'll start tracing the ground wire and do some diggin on that box and report back.
Title: Re: Rear Light Problems
Post by: WoahGold on August 10, 2012, 08:48:57 AM: It's been raining off and on all day so I didn't want to trace the ground, but I found out some info about my mystery box.

(http://i1059.photobucket.com/albums/t433/WoahGold/ba2a407c.jpg)

It is a running light unit, I found the company's website too.
http://www.soundoffrec.com/products/lights.aspx (http://www.soundoffrec.com/products/lights.aspx)

I'd take it out, but I like the extra light in the back and am afraid of how chopped up the wires may be.
If I can't find a problem elsewhere then it'll have to go.

PS Would anyone be able to take a picture of what the stock wiring is supposed to look like? Thanks
Title: Re: Rear Light Problems
Post by: frankenduck on August 10, 2012, 08:59:28 AM: Brown grounds via a daisy chain to both tail and brake bulbs

Gray/black to tail light +

Gray/yellow to brake light +
Title: Re: Rear Light Problems
Post by: 552255 on August 10, 2012, 11:15:27 AM: All of my electrical gremlins (not too many) fuel guage, signals, etc. were due to a faulty ground wire/connector...its also pretty easy to make rear running lights with a dual filament bulb. Can purchase bulb sockets from any auto parts store, and rewire/modify for dual bulb. Good write ups here to show how and on the net.

Rear running lights are a good idea, there isnt much visibility back there...brake lights same thing.
Title: Re: Rear Light Problems
Post by: frankenduck on August 10, 2012, 11:25:01 AM: If just the brake and tail lights are doing this then it's most likely that ground wire. Dirty starter issues usually manifest themselves in freaky turn signal behavior.

One caveat on rear Run-N-Lites: Filament bulbs left on constantly generate heat. K bike lenses are not designed for that and rear Run-N-Lites will, over a long span of time, gradually warp the lenses a bit. I've seen it on several bikes that I've parted out that had them.

Lite-Buddies are better IMO.

And a 56011 Lite-Blazer license plate frame is even better than that.

(http://smithduck.home.comcast.net/~smithduck/bmw/k1100rs/pics/licframe.jpg)
Title: Re: Rear Light Problems
Post by: Motorandy123 on August 10, 2012, 11:34:24 AM: My thought is they use diodes to steer the running lights into the blinkers so
a problem with the brake would knock out all lights back there.
Title: Re: Rear Light Problems
Post by: frankenduck on August 10, 2012, 11:42:23 AM: Quote from: Motorandy123 on August 10, 2012, 11:34:24 AM
My thought is they use diodes to steer the running lights into the blinkers so
a problem with the brake would knock out all lights back there.

Most flasher dealy-bobs I've seen tap into the running light wire for constant power so the flasher dealy-bob shouldn't cause the tail light to go out. That's why I suspect a bad ground. (Unless it's a Scotchlok tap cutting the tail light wire. I hate those things!)
Title: Re: Rear Light Problems
Post by: WoahGold on August 16, 2012, 06:45:11 PM: EPIC CONCLUSION

I finally had a chance to tear into the bike today. Though to be fair i was spurred on by a fuel leak from a cracked feed line. But I ran through the wiring and cleaned contacts and checked for any shorts or bad insulation. There were none...

So after finishing the fuel line job I pulled the rear light to check the wiring back there. Turns out that the ground wire into the plug was loose, as was the plug itself (It looks like the catch may have been broken off). So I cleaned it and secured it with electrical tape and now it seems to be working. Thanks for the help everyone.