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Hey guys-

So I have a 2018 Grom w/ ABS (it was the only one left as I rather not have ABS). I just changed sprockets from the factory 15/34 to a 14/36 set up and I love it. The only issue is now after riding for 10 minutes or so the ABS light comes on and continuously flashes at me. I have yet to find any cause or fix online - I called our Honda dealer and they really weren't aware of any known fixes yet either unless I take the bike in so they can run a diagnostic. I'm assuming it may be a speed sensor due to the gearing change which effects RPM's etc.?

Any help is appreciated!

Thanks
 

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Try resetting the ECU
 

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does the ABS grom have a ring sensor on the rear disk like it does in the front? If not, its likely using the speed sensor on the motor and due to gear change it now sees a continual difference in speed between front and rear and is throwing a code. That would kinda suck.

Edit - from what i can tell in pictures there is no sensor ring on the rear of the abs grom... hence it uses speed sensor and why you are having this issue.
 

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I’m running different gearing on an ABS model without issue FWIW
 

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does the ABS grom have a ring sensor on the rear disk like it does in the front? If not, its likely using the speed sensor on the motor and due to gear change it now sees a continual difference in speed between front and rear and is throwing a code. That would kinda suck.

Edit - from what i can tell in pictures there is no sensor ring on the rear of the abs grom... hence it uses speed sensor and why you are having this issue.
The gearing won't make a bit of difference. The wheels still have to turn at the same speed - or someone will be up for a new tyre real quick.
 

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The groms speedometer is in the transmission. Some bikes its on the front wheel, which doesnt need calibration. Get a speedo healer. Easy to install, set up and use.
 

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The gearing won't make a bit of difference. The wheels still have to turn at the same speed - or someone will be up for a new tyre real quick.
correct, but if the abs control unit is looking at rear wheel speed on the motor side (where a stock grom gets a speed reading for the speedo) then yes a gearing change will effect how the abs unit sees rear tire speed.

Can someone confirm or deny if there is an abs ring on the rear disk?
 

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correct, but if the abs control unit is looking at rear wheel speed on the motor side (where a stock grom gets a speed reading for the speedo) then yes a gearing change will effect how the abs unit sees rear tire speed.

Can someone confirm or deny if there is an abs ring on the rear disk?
fiche shows it on the front (12): https://www.partsfish.com/oemparts/a/hon/5989f03487a86612c4ea8043/front-wheel
doesnt show anything on the back: https://www.partsfish.com/oemparts/a/hon/5989f03487a86612c4ea804c/rear-wheel

it would be absurd** to include one on the back when the only difference that should be reported between the output shaft speed and the rear wheel speed would be when someones got their chain really loose, and is going off/on the throttle.

**on a cheap bike like the grom**

Clear the code, and see if it appears again.
If it does, clear it and go back to the stock sprocket. See if the light comes on again.
 

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I'm having this same problem after the same gearing change. Does anyone know if indeed it's the now uncalibrated speed vs front wheel rotations that's causing this? If this is the problem I can throw a speedo healer on it but otherwise I really don't care if the speedo is off.
 

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I'm having this same problem after the same gearing change. Does anyone know if indeed it's the now uncalibrated speed vs front wheel rotations that's causing this? If this is the problem I can throw a speedo healer on it but otherwise I really don't care if the speedo is off.
It is 100% the gearing change that is making the light flash. Depending on gearing, it has to see a pretty large difference to actually set the light off. Mine was 14t/41t. I had the same issue and going back to the stock sprockets fixed it.
 

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It is 100% the gearing change that is making the light flash. Depending on gearing, it has to see a pretty large difference to actually set the light off. Mine was 14t/41t. I had the same issue and going back to the stock sprockets fixed it.
12 o’clock labs speedo healer resolved the problem.
 

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After lots of reading i'm thinking about my first engine mod changing the front sprocket with a 14t sprocket and keeping the rear 34t sprocket to make 4th gear more responsive. I have the 2017 abs model and would like to know if with this gearing change my abs will get into issue like some of you had or will it be ok?

Thank you
 

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After lots of reading i'm thinking about my first engine mod changing the front sprocket with a 14t sprocket and keeping the rear 34t sprocket to make 4th gear more responsive. I have the 2017 abs model and would like to know if with this gearing change my abs will get into issue like some of you had or will it be ok?

Thank you
Yes you will. The ABS "brain" compares the rotation of the front wheel with the rotation of the rear and when you change the gearing you've introduced a different ratio of front vs rear wheel rotations. My Grom would throw the ABS fault on the dash after several minutes of riding and do it every time until I installed the 12 o'clock labs speedo healer. That install was very simple, plug and play with the existing wiring on the bike. No cutting or splicing or any changes to the bike's wiring other than plugging in the device. Programming it for you exact speedo error is also very well explained on their web site and worked exactly as described. Overall this was one of the most straight forward and easy mods I've ever made to a motorcycle so I bought another one to put on my WR250R. It doesn't have ABS but the speedo was way off due to a pretty radical gearing change I made on that bike for crawling around in rock gardens and technical trails in the woods.
 

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Thanks a lot twist for your quick answer, i'll have to order the 12 o'clock labs speedo healer from US because in Spain i can't find a speedo healer for my grom, and europe dealers for the 12 o'clock labs stuff look like the don't work anymore.
 

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Thanks a lot twist for your quick answer, i'll have to order the 12 o'clock labs speedo healer from US because in Spain i can't find a speedo healer for my grom, and europe dealers for the 12 o'clock labs stuff look like the don't work anymore.
HealTech in the UK has a speedo healer for the grom as well.

 

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Thanks mingo, very useful your info, saw your post and searched the web and found a healtech electronics dealer in Spain too www.motorvista.es so i guess i'll go for this one, specifically speedohealer sh-v4+sh.h11.
 

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Hi everyone, changed the rear sprocket to 36t and try without the speedohealer and no issue by the moment, EU speedometer isn't very accurate, marking 100km/h is by GPS 90km/h with stock sprockets, now with the 36t is less accurate, speedometer marking 100km/h and 85km/h by GPS, but no issue with the ABS. I need to test it properly wot and in a log run, i just did for half an hour but no issues by now.
 
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