Author Topic: V7 III - rear brake not activating brake light  (Read 478 times)

Offline agdrache

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V7 III - rear brake not activating brake light
« on: June 05, 2023, 10:34:48 AM »
I noticed recently that my brake light doesn't come on when I use the rear brake alone, only when I also use the front. Obviously this is not ideal in all conditions. I checked the connector from the brake pedal next to the battery, and the connections appeared to be fine (although I haven't hit it with any kind of electrical contact cleaner yet). Where else should I be looking?

I also recently noticed that my rear right turn signal has stopped working a couple times, but is otherwise fine, and doesn't seem to be predictable in any way. Usually it works fine, but on two rides, I suddenly started getting the double-time flash on the dashboard indicator, with confirmation from the friend I was riding with one of those times that the light wasn't working.
2018 MG V7 III Stone
2011 Suzuki TU250X

Offline twowheeladdict

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Re: V7 III - rear brake not activating brake light
« Reply #1 on: June 05, 2023, 11:45:07 AM »
Based on both issues, I would look at the wiring all the way to the tail end of the bikes for any signs of a chaffed wire.  Also check the connectors along the way by disconnecting and reconnecting.  Also, using the wiring diagram, check all the grounds in the area. 

You can check the rear brake switch with an ohmmeter with power to the bike off. 
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2018 V7 III Carbon Dark #0009 of 1921
2018 Road Glide Special
2021 Kawasaki KLX300SM
2017 Suzuki Van Van 200
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Offline agdrache

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Re: V7 III - rear brake not activating brake light
« Reply #2 on: June 06, 2023, 01:22:53 PM »
Based on both issues, I would look at the wiring all the way to the tail end of the bikes for any signs of a chaffed wire.  Also check the connectors along the way by disconnecting and reconnecting.  Also, using the wiring diagram, check all the grounds in the area. 

You can check the rear brake switch with an ohmmeter with power to the bike off.

Awesome, thanks. Hopefully I'll have a nice-weather day soon where I can look at that in detail (since I don't have a garage)
2018 MG V7 III Stone
2011 Suzuki TU250X

Offline agdrache

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Re: V7 III - rear brake not activating brake light
« Reply #3 on: June 07, 2023, 06:56:22 PM »
Based on both issues, I would look at the wiring all the way to the tail end of the bikes for any signs of a chaffed wire.  Also check the connectors along the way by disconnecting and reconnecting.  Also, using the wiring diagram, check all the grounds in the area. 

You can check the rear brake switch with an ohmmeter with power to the bike off.

Checked the rear brake switch with the continuity tester on my multimeter, that seems to be the cause of the brake light issue. I tracked down a replacement and ordered that. I haven't had a chance to look closer at the turn signal thing yet, though
2018 MG V7 III Stone
2011 Suzuki TU250X

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Re: V7 III - rear brake not activating brake light
« Reply #3 on: June 07, 2023, 06:56:22 PM »

Offline agdrache

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Re: V7 III - rear brake not activating brake light
« Reply #4 on: June 10, 2023, 06:45:27 PM »
Based on both issues, I would look at the wiring all the way to the tail end of the bikes for any signs of a chaffed wire.  Also check the connectors along the way by disconnecting and reconnecting.  Also, using the wiring diagram, check all the grounds in the area. 

You can check the rear brake switch with an ohmmeter with power to the bike off.

The switch appears to have been the issue for the brake light. I checked it with a multimeter after work the other night and ordered a replacement. I got the replacement partly installed this evening, just need to replace the zipties that keep it in place. I only stopped where I did because it started raining.....but the rear brake is once again turning the brake light on!

The turn signal issue looks to be just a sketchy connection inside the fixture. I pulled the bulb out and sanded off some rust that had developed, and it's been working fine the last couple days, but I'll give it some more attention tomorrow when the weather should be better suited to doing that. I also might just see about replacing them all with the OEM LED ones if I decide that I feel like spending that money
2018 MG V7 III Stone
2011 Suzuki TU250X

Offline twowheeladdict

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Re: V7 III - rear brake not activating brake light
« Reply #5 on: June 11, 2023, 06:47:31 AM »
The switch appears to have been the issue for the brake light. I checked it with a multimeter after work the other night and ordered a replacement. I got the replacement partly installed this evening, just need to replace the zipties that keep it in place. I only stopped where I did because it started raining.....but the rear brake is once again turning the brake light on!

The turn signal issue looks to be just a sketchy connection inside the fixture. I pulled the bulb out and sanded off some rust that had developed, and it's been working fine the last couple days, but I'll give it some more attention tomorrow when the weather should be better suited to doing that. I also might just see about replacing them all with the OEM LED ones if I decide that I feel like spending that money

Glad it worked out for you. Ride safe.
2022 Moto Guzzi V85TT Guardia D'onore
2018 V7 III Carbon Dark #0009 of 1921
2018 Road Glide Special
2021 Kawasaki KLX300SM
2017 Suzuki Van Van 200
2009 Harley Davidson Softail Custom

Offline mechanicsavant

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Re: V7 III - rear brake not activating brake light
« Reply #6 on: June 12, 2023, 06:50:44 AM »
Another good reason to at some convenient time remove all bulbs, not in the instrument cluster & put a dab of Vaseline or dielectric goo on the contacts

 

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