Brake light always on - 1979 GS850

[Steve]

I've also reconnected the front brake light wires to the plate. Still, no luck on the brake light turning on.

What "plate"?

There is no "plate" in relation to brake light wires.

There is a wire that branches and feeds both, the front and rear brake light switches. There is another wire that comes from both switches (and joins together), then feeds the brake light. There is no "plate" anywhere.

I think it has been hinted at here in this thread (I have helped in a couple other wirng threads recently, so am not sure if it was this one), but I am going to come right out and plainly ask you to do some testing, not guessing.

Look in front of the brake light housing. That would be under the "glove box" inside the tail fairing, behind the seat. You should see a flat, three-pin white plastic connector that feeds your tail light assembly. Note that there are three wires there, a black with white stripe (ground wire), brown (tail) and white (brake). Separate the connector. Use a piece of wire about two feet long (you do have some spare wire sitting around, don't you? If not, go get some), strip a bit of insulation off each end. Insert one end into the connector that is attached to the tail light, connect the other to a good ground (chassis, battery, whatever). Take another piece of wire about the same length, strip some insulation from both ends. Connect one end to a power source (fuse box, battery, whatever). Be careful that the other end does not touch any metal, or there WILL be fireworks. Touch the loose end to the brown wire in the tail light connector. You should see both bulbs light up, and be about equally bright. Now remove the wire from the brown wire and touch it to the white one, the brake light should come on brightly, the license light will not be on. If those simple tests do not work as described, you have problems with your tail light housing, the socket or the bulb.

.

[natejelovich]

What "plate"?

There is no "plate" in relation to brake light wires.

There is a wire that branches and feeds both, the front and rear brake light switches. There is another wire that comes from both switches (and joins together), then feeds the brake light. There is no "plate" anywhere.

Hi Steve,

Sorry, should have included pictures as I figured my description would be confusing... Anyway, the "plate" I was referring to was the front brake switch plate.



This is what started this whole issue... I was fixing my front MC and the wires on this broke off. I soldered them back on, but now I have this other issue... no brake light.

I think it has been hinted at here in this thread (I have helped in a couple other wirng threads recently, so am not sure if it was this one), but I am going to come right out and plainly ask you to do some testing, not guessing.

Yes, thank you! I am such an amateur at all of this I don't even know how to do proper tests or where to start. So, I really appreciate all of your help!!

Look in front of the brake light housing. That would be under the "glove box" inside the tail fairing, behind the seat. You should see a flat, three-pin white plastic connector that feeds your tail light assembly. Note that there are three wires there, a black with white stripe (ground wire), brown (tail) and white (brake). Separate the connector. Use a piece of wire about two feet long (you do have some spare wire sitting around, don't you? If not, go get some), strip a bit of insulation off each end. Insert one end into the connector that is attached to the tail light, connect the other to a good ground (chassis, battery, whatever). Take another piece of wire about the same length, strip some insulation from both ends. Connect one end to a power source (fuse box, battery, whatever). Be careful that the other end does not touch any metal, or there WILL be fireworks. Touch the loose end to the brown wire in the tail light connector. You should see both bulbs light up, and be about equally bright. Now remove the wire from the brown wire and touch it to the white one, the brake light should come on brightly, the license light will not be on. If those simple tests do not work as described, you have problems with your tail light housing, the socket or the bulb.

I'll try this out. I think my connector is outside of the hosing box (see picture below) but I'll see if I can get any light that way and see what happens. Again, thanks for your tips!!

[Steve]

..., the "plate" I was referring to was the front brake switch plate.

OK, now it makes sense. Do you have all the other little parts that go to the switch? There should be a little square black plastic piece, a spring and a piece of U-shaped copper. If you don't have ALL of them, the switch will not work properly. The good news is that you can get replacement switches for less than $10.

This is what started this whole issue... I was fixing my front MC and the wires on this broke off. I soldered them back on, but now I have this other issue... no brake light.

No problem. As previously mentioned, make sure you have all the parts or buy a new switch, if needed.

Yes, thank you! I am such an amateur at all of this I don't even know how to do proper tests or where to start. So, I really appreciate all of your help!!

Believe it or not, that's why we are here.

I'll try this out. I think my connector is outside of the hosing box (see picture below) but I'll see if I can get any light that way and see what happens.

Yep, that's the connector right there, hanging with the other wires.

Just pull that connector apart and do the testing in my post #17.

Testing in a systematic way will eliminate variables as you go. The test I described will tell you whether the lights themselves are working.

Once we see the results of those tests, we will move on to the next one.

.

[natejelovich]

Thanks Steve!!

Yes, got all the parts (including the small plastic piece with copper and spring).

I'll give your test a try and post the results.

Thanks again, really appreciate it!

[natejelovich]

Just pull that connector apart and do the testing in my post #17.

Testing in a systematic way will eliminate variables as you go. The test I described will tell you whether the lights themselves are working.

Once we see the results of those tests, we will move on to the next one.

.

OK, gave the test a shot (thanks for the clear instructions!).

Test #1: Both lights came on a low/dim level when I powered the Brown (tail) wire



Test #2: Only the license plate light came on when I powered the White (brake) light



Hopefully you can see the proof of my method on the ride side (first is touching the brown wire, second is touching the white).

I just replaced the brake/tail light bulb today (to make sure it wasn't just a dead light) so I'm thinking that's not the issue.

Interestingly, you mentioned the license plate light should go off when I touch the white one, but it's staying on... not sure if that means anything or not, but that's where I'm at!

Thanks again Steve! Not sure what this means now though...

[Steve]

Test #2: Only the license plate light came on when I powered the White (brake) light



Interestingly, you mentioned the license plate light should go off when I touch the white one, but it's staying on... not sure if that means anything or not, but that's where I'm at! ...

Not only is it on, it looks like it's BRIGHTER!

You obviously have some problems with the wiring in the tail light. Remove it from the bike so you can see where all the wires go.

.

[natejelovich]

Not only is it on, it looks like it's BRIGHTER!

You obviously have some problems with the wiring in the tail light. Remove it from the bike so you can see where all the wires go.

.

Yes... it is brighter. I should also mention:

1. When I touched the hot wire to the ground (black) wire, the same thing was happening as test #2 (only the tag light came on at the same brightness)

2. You mentioned the light should be an 1157, but what was in there before, and what I have in there now is a 1034. Would that make any difference here?

3. The tail light filament never came on any of the tests

I'll remove the housing. Thanks!!

[Steve]

Yes... it is brighter. I should also mention:

1. When I touched the hot wire to the ground (black) wire, the same thing was happening as test #2 (only the tag light came on at the same brightness)

2. You mentioned the light should be an 1157, but what was in there before, and what I have in there now is a 1034. Would that make any difference here?

3. The tail light filament never came on any of the tests

I'll remove the housing. Thanks!!

OK, more questions:
1. When you touched the hot to the black wire, where was your ground wire?
That black wire is for GROUND ONLY, the hot wire should never touch it.

2. A 1034 is OK, they are sometimes harder to find. Either one will work.

3. And yet, it did in a previous test.


Your license light (the lower one) should have a single-filament bulb, probably a 67 or an 89. It should only be ONE brightness, because it only has a single filament.

In one of your previous posts, you show both filaments ON, apparently while following a request to ground the black wire and power the brown wire. Your next test, powering the white wire, changed the brightness in the wrong bulb. I have a sneaking suspicion that somebody has crossed up some wiring or swapped sockets for the lights. How that might have happened, I don't know, but "previous owners" can be really crafty people.

I will repeat a previous request: remove the whole assembly from the bike so you can track where the wiring goes.

.

[natejelovich]

OK, more questions:
1. When you touched the hot to the black wire, where was your ground wire?
That black wire is for GROUND ONLY, the hot wire should never touch it.

2. A 1034 is OK, they are sometimes harder to find. Either one will work.

3. And yet, it did in a previous test.


Your license light (the lower one) should have a single-filament bulb, probably a 67 or an 89. It should only be ONE brightness, because it only has a single filament.

In one of your previous posts, you show both filaments ON, apparently while following a request to ground the black wire and power the brown wire. Your next test, powering the white wire, changed the brightness in the wrong bulb. I have a sneaking suspicion that somebody has crossed up some wiring or swapped sockets for the lights. How that might have happened, I don't know, but "previous owners" can be really crafty people.

I will repeat a previous request: remove the whole assembly from the bike so you can track where the wiring goes.

.

Sorry, meant brake light, not tail light. The brake light never came on in any of the tests. The tail light did...

I grounded the wire to the bike. I did touch the black (ground) with the hot wire, and it only turned on the license plate light (that same brightness)....

Here's the wiring. I think it looks good, but I don't know much!

[cowboyup3371]

Something about the connector at the harness area isn't right. Take a good picture of that please so we can see it better.

[Steve]

OK, more questions:
1. When you touched the hot to the black wire, where was your ground wire?
That black wire is for GROUND ONLY, the hot wire should never touch it.

I grounded the wire to the bike. I did touch the black (ground) with the hot wire, and it only turned on the license plate light (that same brightness)....

Something is getting lost in the transfer of information here, not sure on which end, though.

If I am understanding this correctly, I asked where your ground wire was. You said it was grounded to the bike. Earlier, I asked you to connect one end of a wire to either the chassis or the battery negative terminal, and connect the other end to the black wire that goes to the tail light. Evidently that was not connected in that manner, because if it was, when you touched the hot wire to the black wire, you would have had FIREWORKS.

Please verify for my simple little mind:
- One end of a wire is connected to battery (-) or the chassis, the other end stuck into the white 3-pin connector at the tail light, and touching the black wire ONLY.
(Do not connect it to the side of the connector that is attached to the wire harness on the bike, go to the connector that is attached to the tail light.)

- One end of another wire is connected to the battery (+), the other end is being held in your hand for testing.

- With the free end of the "hot" wire, touch the brown wire in the 3-pin connector. What lights up? How bright is it?

- With the free end of the "hot" wire, touch the white wire in the 3-pin connector. What lights up? How bright is it?

.

[natejelovich]

Hi Steve,

Yes... I think something did get lost in the transfer! From your earlier note, this is what I did:

Insert one end into the connector that is attached to the tail light, connect the other to a good ground (chassis, battery, whatever).

So, now it sounds like there should be mention of the ground wire being grounded... from the quote above, it sounded to me like I was supposed to ground the brown (tail light) wire... Again, amateur here so everything (though it sounds a bit off) sounds right to me!

I did ground the wire to the chassis, but I inserted the grounded wire into the brown connector.

Please verify for my simple little mind:
- One end of a wire is connected to battery (-) or the chassis, the other end stuck into the white 3-pin connector at the tail light, and touching the black wire ONLY.
(Do not connect it to the side of the connector that is attached to the wire harness on the bike, go to the connector that is attached to the tail light.)

I will give the updated version a try.

[natejelovich]

Something about the connector at the harness area isn't right. Take a good picture of that please so we can see it better.

Is this what you need?

[natejelovich]

Hi Steve,

I will give the updated version a try.

Just did... and same result. Grounded the wire to the bike, and plugged it into the black (ground) wire in the white connector. Then, plugged another wire into the battery and the other end into the brown (both bulbs dimly lit, but only one filament on the brake light) and then the white (only the license plate light brightly on).

[cowboyup3371]

Is this what you need?

First, I'm nowhere the electrical expert that Steve is so please continue to listen to him. He has helped many a person through electrical issues here.

However, something is very definitely wrong. The top connector there is your taillight/brake light connector from the harness that should plug into your connector at the bottom. The two black and white bullet connectors in the harness should be the grounds for your turn signals while the green and white bullet connectors in the harness are for power to the signals. So, why do you have an extra white wire coming from the taillight/brakelight wiring section?

I'd remove the tape or harness covering from both sections and really look them over before doing anything else. I think someone else might have jerry-rigged that section to fix another problem instead of just doing it correctly.

Do you have a copy of your bike's wiring diagram? If not, get to Basscliff's site and download it.