[Papichungo]

2012 800R. Both brake lights work properly, starts while in gear with foot on brake As well as like normal in park and neutral. I start out with that because I have read other searches talking about a faulty brake light sensor. Brakes worked fine before and after the 2 incidents described below. No grinding, squealing pads, peddle felt solid not soft of spongy. bike not overheating.

Today after only about 5 minutes of riding in very dry sugar sand, the bike acted like it was dying (I played with the throttle a little and it kept going). About 30 seconds later, I could tell I had a serious drag issue. I let off gas and it quickly came to a stop. I gave it gas and it was obvious that the brakes were locked, As I was pretty excellerated and really bogged down like brakes we being applied. No dash warning messages or check engine lights came on. My actions:
1. Turned off bike, let dash reset, started bike= brakes locked
2. Disconnected brake sensor switch (master cylinder area) = brakes locked
3. With sensor disconnected, shut off bike, let dash reset = brakes locked
4. Disconnected Battery for 30 sec= Brakes UNLOCKED
Rode for 3 more minutes until brakes locked up again. I tried #1 above without success then did #3 which worked again and drove it back to camp for about 8 minutes. Bike drove back fine without issue through same terrain.
Without a jack I was not able to lift Bike and try to spin wheels, to confirm brakes locked, but it didn’t feel like it was just one. Also by disconnecting the battery to RESET something, it sure seems electrical/sensor type thing. Anyone have this happen to them or idea how to fix.

 

[acefire]

Other than the brake light switch there is nothing in the braking system that connects to the ecm. So disconnecting the battery had nothing to do with releasing all or even one of the brakes. As for why the brake is locking up sound like it's heat related brake is dragging and building heat . Then locking up.

 

[GolfCart]

Water in the brake fluid may cause this. If the brakes get hot enough to boil the water the expansion of the water boiling will push on calipers.
Also if the master cylinder plunger is not returning to released position when brake pedal is released the brake fluid in the brake lines will not return into the master cylinder. After a few times of pressing the brake pedal the fluid will build up enough pressure to lock the brakes.
Neither of these conditions would have anything to do with the battery. Maybe the time you waited with the battery disconnected allowed the brake fluid to cool or slowly drain back into the master cylinder.