Tail light not working

[sinkankan]

I've got a 1981 GS850, with a brand new harness, brand new ignition switch, brand new handlebar switch, and my problem is the tail light works but not the brake light. Earths have been installed back to the frame (scratched the paint off) from the black and white wire. Bike cliffs wiring diagrahm doesn't show an actual light switch, until you go to a black & white schematic. Also the number plate light isn't working at all, the switch has been pulled apart and all looks good. I've run a direct wire to the White wire coming off the headlight, and the tail light lights up, but no brake light. Take the wire off and I get a brake light, is there a 'jump wire somewhere I'm missing. Headlight works fine, also the high beam as well.
I reckon there might be a break in the harness somewhere, (dodgy electrical connection maybe), as it's got me stumped to where the break may be.
any help would be appreciated.

 

[Guest]

I had a similar problem a few years ago. In my case it was the wiring that runs through the grommet and under the rear fender. It had come off one of the clips and was chafing at the top of the rear wheel.

 

[sinkankan]

I had a similar problem a few years ago. In my case it was the wiring that runs through the grommet and under the rear fender. It had come off one of the clips and was chafing at the top of the rear wheel.

Thought I solved it, the cheap new ignition switch brown wire actually wasn't live, (no power) by installing a jumper wire across from the red (power) to the brown wire it solved the problem. Brake lights works, number plate light works, tail light works. But the tail light now stays on, so now I have to find the switch wire from the handle bars to break into that one. If that proves too hard I'll rig up a switch somewhere on the bike to isolate the power to the back light. None of the schematics actually show a switch to turn the lights on/off.
Funny how the auto sparkie that did this new harness never picked it up!, he definetly won't be getting any business or recommendations from me.

 

[Brendan W]

Solved it, the cheap new ignition switch brown wire actually wasn't live, (no power) by installing a jumper wire across from the red (power) to the brown wire it solved the problem. Brake lights works, number plate light works, tail light works.
Funny how the auto sparkie that did this new harness never picked it up!, he definetly won't be getting any business or recommendations from me.

Won't that mean the tail and licence plate light are permanently live ?
Was the replacement switch oem or some other ?
If it was oem used I would be tempted to open it up and check all the contact plates.

 

[sinkankan]

Yeah, didn't work. The switch has been opened up and checked and everything looks ok. I'll take it to an auto electrican after the holidays, just cheesed off that the original guy let the bike out of his workshop with no working brake lights.

 

[Steve]

Look carefully at the ignition switch, you will see four wires: red, orange, gray, brown. The red wire is "hot" all the time (assuming the MAIN fuse is intact), and fed by the battery and R/R output. When the key is turned to the ON position, the red wire is connected to the orange wire, which feeds the fusebox and then the rest of the bike. With the fusebox powered, current can flow through the LIGHTS fuse and out via the orange/red wire. One of the places that wire goes is a four-pin connector (under the gas tank) that also holds the infamous "stator loop". On the other side of the connector, the wire color changes to yellow/white and goes to the headlight beam selector switch. At the connector, it also loops back to the fourth pin, where it comes out as a gray wire. That gray wire feeds the lights in the instrument cluster and also go to the ignition switch. The key is still ON, so that gray wire is connected to the brown wire, which goes directly to the tail light.

Why is the tail light fed by this convoluted system? Simple. Look at the pin connection for the ignition switch, you will see that when it is in the PARK position, the red wire will be connected directly to the brown wire. That will turn on the tail light, and nothing else on the bike. It is intended as a safety device if you ever have to leave the bike on the side of the road at night, but all it seems to do is to drain the battery in less than an hour.

Don't blame your sparky for not understanding this system. Unless he is very familiar with motorcyle wiring, he may not know that such a system exists. Now, if he was following a wiring diagram, there shouldn't be any excuse, so go ahead and blame him.

Back to your problem. You say the brake light does not work. How about the horns, oil warning light or turn signal? If neither one of them works, check the SIGNALS fuse. If the horns and turn signals work, check your brake switches. They are fed by the orange/green wire that comes from the fuse, then connect to the white wire that goes to the brake light. It's easy enough to use a test light to check continuity at the various connectors to see if you have power there.

By the way, the best COLOR diagram for your bike is also on BassCliff's site, but is labeled as an '80 diagram. It doesn't matter, '80 and '81 are identical. Click HERE for that diagram. I have found that diagram to be the best one for most of the GS line. Yeah, there are differences in some models where there are features that did not exist on the '80 850, but the wire colors were remarkably consistent throughout the series.

.

 

[GSXR7ED]

Good info...thx fellas. I'm having blinker probs (last I checked which was ages ago)...but will use this for reference.


Ed