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Discussion Starter · #1 · (Edited)
I just bought an 86' VT700C and it runs great. However, the brake light doesn't work. I'm sure the brake light switch is just fine, as the indicator on my dash lights up whenever I depress either the front or the back brake. The only issue is that the brake light in the rear does nothing.

I tried switching the bulb expecting that it could be that one of the filaments that is bum, but both filaments were just fine and the brand new bulb worked the same.

I was wondering if anybody might have a suggestion on how to fix this? The only theory I have come up with, is that there is a blown fuse and for some reason this locks the brake light either always on, or always off (the tail light seems unusually bright to me, but I could be wrong)?

Thanks!
-Nico
 

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Get your wiring diagrams and check for shorted or open wires running from the switches to the light. Also Disconnect the wires for both of the switches and make sure they do open and close as you operate the brake. Check the socket and make sure the contacts aren't bent, broken, or otherwise damaged or dirty...

Are both filaments always on or just one of the two?
 

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The dash light is a warning indicator that your brake light is failed. Check for power to the bulb and a good ground leading away.
 

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My schematic is for an 88 but the colors should be the same. Green wire is ground. Green/Yellow is switched +12 and us common to both switches. There will be a disconnect probably under the seat and it's a safe bet a bullet connector is loose or pulled out there. The only other disconnects are for the switches themselves and they are probably good since you are getting an indicator at the gauge.
 

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First question - is your taillight lit at all without the brake? They use the same ground.

If no lights, you have a bad ground.

If normal taillight / no brake light, you have a bad feed to the brake light.

If always bright, you have constant brake light and either a short between tail & brake or a bad brake switch, etc.

Once we can break it down to one of these three paths, we can narrow our scope pretty quickly.
 

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Yea, three wires and two of them are eliminated since the taillight works. Math cannot get simpler than that.
 

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Check the Brake light 12V feed...
The wire probably has an open curcuit between the switches and brakelight somewhere...

Unfamiliar with yours...

Merry Christmas & Good Luck on this diagnosis
Ann & Dennis
I had to run a wire to get the rear brake to turn on the brakelight on my 98 model :D
 

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I have the same bike...shes in my signature below, Jezebel. You have a blown tail light fuse...this is indicated by the tail light indicator lamp on the instrument cluster being lit.

With your bike on the center stand or kick stand, turn your handlebars all the way to the right as if you were riding. Look directly under the Left Side near the Triple Tree/Neck...you should see a small 1-1/2" x 3" or so plastic cover...it is held in place by 2 Phillip-headed screws. Take the screws out and pull the cover...it can be a slight pain in the rear. Tour tail light fuse should be the 5th down from the top..it is 10 amp blade fuse...replace it.

If you replace the fuse, the dash indicator lamp should go out. If it blows again, look for a shorted wire somewhere...trace from the tail light back...

See attached image below...
 

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Discussion Starter · #10 ·
Thank you for all of your help guys! Keep in mind, I'm brand new to owning and working on bikes, so please bear with me as I try to figure this out.

I was able to change out the fuse for the brake light, and it made no difference. I bought a smart fuse and it does not indicate that it has blown either. So the fuse is good, and I've started looking into the wiring now. Currently I'm trying to figure out how to expose the line for my inspection from the tail light to the brakes. First, what is the easiest way to remove the front seat? Also, which connections should I be focusing on, and where can I find them on the bike? I have a copy of the 86-87 service manual, which includes the wiring diagrams, so I can look at those, but I can't promise I'll understand it all the first time.

Thank you again guys, I really appreciate all of the help!
 

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While checking connections, be sure to tighten up any loose bullets...
The service manual is a very important tool...
Follow the instructions and you`ll get the job done...


Merry Christmas,
Ann & Dennis


Welcome to the forums :D
 

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Thank you for all of your help guys! Keep in mind, I'm brand new to owning and working on bikes, so please bear with me as I try to figure this out.

I was able to change out the fuse for the brake light,
Ok, lets start right here...I cut the rest of your quoted post because this may be where your problem is. So lets clarify for a second.

Is the Tail Light Indicator on the instrument cluster on, and do you have brake lights when you either squeeze the front brake lever or press the rear brake pedal? If you have brake lights, then by all means the brake light fuse you checked is good. Did you check the Tail Light fuse as well? Was it good?

If you go back and look at the fuse panel and cover picture I posted, you will see that the Brake is also joined by Turn & Horn. If all 3 of these items are working, your fuse there is indeed good. If you have no Tail Light, it is usually 1 of 2 items, either the 10amp fuse is blown, or the filament on the tail light/brake light bulb is burned out. Please recheck the fuse panel...pull that 10amp fuse marked METER TAIL...I would almost bet a hole in a donut that that fuse is blown....
 

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I do not trust my eye sight when checking fuses. I always use a multi-meter to check the fuses to see if they have a open circuit. I also put the positive lead in the fuse block and ground the negative lead too check for voltage and amps in the block. Make sure you have power.
 

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I do not trust my eye sight when checking fuses. I always use a multi-meter to check the fuses to see if they have a open circuit. I also put the positive lead in the fuse block and ground the negative lead too check for voltage and amps in the block. Make sure you have power.
Years ago I spent hours troubleshooting a very odd automotive problem in which a spade-type fuse had an ever so tiny 'fault line' in the filament. It was not quite open, not quite a full connection. It was a resistor of sorts. Forehead slapper. I've used an ohm meter from then on.
 

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Discussion Starter · #15 ·
Is the Tail Light Indicator on the instrument cluster on, and do you have brake lights when you either squeeze the front brake lever or press the rear brake pedal? If you have brake lights, then by all means the brake light fuse you checked is good. Did you check the Tail Light fuse as well? Was it good?

If you go back and look at the fuse panel and cover picture I posted, you will see that the Brake is also joined by Turn & Horn. If all 3 of these items are working, your fuse there is indeed good. If you have no Tail Light, it is usually 1 of 2 items, either the 10amp fuse is blown, or the filament on the tail light/brake light bulb is burned out. Please recheck the fuse panel...pull that 10amp fuse marked METER TAIL...I would almost bet a hole in a donut that that fuse is blown....
If by the instrument cluster, you mean the lights just below the speedometer that indicate (from top left) left turn, oil, brake light, right turn, (2nd row) neutral, high beam, and OD, then my brake light indicator comes on every time I depress the front or rear brakes (but only when I do this). However, the brake light on the tail does nothing. I have been able to determine that both filaments on the tail light are in fact burning constantly without either of the brakes being depressed.

As for fuses, I'm not sure what the difference between the tail light and brake light fuses are. The box I opened had 7 slots as follows from top to bottom: STOP TURN HORN, IGNITION, OIL NEUTRAL, HEAD, METER TAIL, FAN MOTOR, and PARKING. I replaced the METER TAIL fuse this morning and there was no change. Also, my turn signals and horn work just fine, so I don't believe there is anything wrong with the STOP TURN HORN fuse.
 

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Discussion Starter · #16 ·
Also, some pointers on removing the front seat would be really helpful in getting a look at the connections.

Thanks!
 

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I have been able to determine that both filaments on the tail light are in fact burning constantly without either of the brakes being depressed.
There's your problem. You have a short between the taillight feed & the brake light feed. It's very likely a Previous Owner has *TRIED TO FIX IT* and you're cleaning up someone else's mess - OR - the short is in the lamp housing. Probably in that order.

Your next step, get the seat off and start measuring resistance between the light channels.
 

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I have been able to determine that both filaments on the tail light are in fact burning constantly without either of the brakes being depressed.

Or a maladjusted switch, stuck switch, or like was said, pinched wire.
 

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Or a maladjusted switch, stuck switch....
Ruled out since the dummy light *only* lights when either lever is activated. If a switch were always on, the dummy light would also be always on.
 

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Ruled out since the dummy light *only* lights when either lever is activated. If a switch were always on, the dummy light would also be always on.
Forgot about that. Yep. Gotta be a pinch or touching bullets.
Sometimes those wires inside the socket get mishandled and their insulation becomes receded, exposing the conductors. Then they can twist a little, cross and touch.
 
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