2021 trek rail 9.9 keeps shutting off

[jhcohan211]

I have called Trek, spoken with the service techs, I’ve spent multiple hours trying to fix this issue. If you hit any bump the whole system will shut off or the motor will cut out for 5-10 seconds and then turn back on. I’ve done the RIB alignment. Anyone else having this issue or have had this issue?

 

[Philly G]

Others have had a similar problem, but that was caused by the bottom battery mount moving, which can't be your issue since you've already done the battery alignment. Maybe the wiring is being pinched between the motor and the frame? Or possibly a loose connection at the motor?

 

[Jumbleross]

Yep I have this issue with my carbon 9.7, my LBS ended up replacing all Bosch parts and I still have the issue. Trek are now sending out a new frame as we think the frame is faulty and over flexing. Take the battery out and check the layups of carbon to see if any of it is peeling away. I suspect Trek will want to rule out lower cost problems before you get to this stage though.

 

[Jumbleross]

FYI mine is an XL and I’m 16 stone so probably max torsional stress. I used to crack ali frames at the welds for fun ?

I’m hoping there is a faulty batch of frames and not a design flaw.

 

[dochabanero]

Yes, I had this on my Rail when ot was new. Adjusting the battery holder made it go away. After that it has been fine despite serious enduro riding, park visits and messy trails.

 

[JacobC1983]

Has anybody had their Kiox lose connection? My Rail 9.9 Will show the speed... then show (--) and stop power assist, then kick back on again? Anybody have any insight into that?

 

[dochabanero]

Has anybody had their Kiox lose connection? My Rail 9.9 Will show the speed... then show (--) and stop power assist, then kick back on again? Anybody have any insight into that?

Some sort of issue with your speed sensor. Look if the connector is properly seated (remove bash guard) and check if it’s properly mounted in the rear triangle/chainstay. Magnet is ok?

 

[JacobC1983]

Some sort of issue with your speed sensor. Look if the connector is properly seated (remove bash guard) and check if it’s properly mounted in the rear triangle/chainstay. Magnet is ok?

didnt know there was a magnet on a Rail? Where is that?

 

[dochabanero]

didnt know there was a magnet on a Rail? Where is that?

It should be held in place with two of the six screws holding the rear disc rotor in place.
Is’s like a small lump if you get my point?

 

[JacobC1983]

It should be held in place with two of the six screws holding the rear disc rotor in place.
Is’s like a small lump if you get my point?

Yep that seems to be secure. Maybe it is on the motor side where the problem is

 

[Martonthego]

Yep that seems to be secure. Maybe it is on the motor side where the problem is

Hi Jacob, did you find the solution? Mine is doing exactly them same thing. They replace the speed sensor, now the motor, and the problem is still there. Please let me know what you’ve done to fix the problem. Thanks

 

[JacobC1983]

Hi Jacob, did you find the solution? Mine is doing exactly them same thing. They replace the speed sensor, now the motor, and the problem is still there. Please let me know what you’ve done to fix the problem. Thanks

I took it in to the bike shop and after some time and trial and error, they basically said they cleaned all the wiring connections and it fixed the issue. They think some dirt/mud was causing a short somewhere.

 

[Martonthego]

Ok thanks, I’ll try it!

 

[JacobC1983]

Ok thanks, I’ll try it!

Best of luck to you.

 

[BuzzinHornets]

I just went through something similar. In my case the battery moving around bent the contact points in the battery in a way that made the connection fragile. RIB alignment, foam pads from the Trek service bulletin and a new battery under warranty and it’s better than ever.

 

[Border T]

I have called Trek, spoken with the service techs, I’ve spent multiple hours trying to fix this issue. If you hit any bump the whole system will shut off or the motor will cut out for 5-10 seconds and then turn back on. I’ve done the RIB alignment. Anyone else having this issue or have had this issue?

I had exactly the same problem on my 2021 Rail 9.8, it's very annoying and can be dangerous. I realigned the battery contacts and the wiring etc but nothing worked. Took it to my LBS who fitted an alloy plate to keep the battery under tension. I was sceptical but several rides later over rough terrain (where previously it would cut out) it seems completely cured. I believe it was ordered from Europe and cost £40 including fitting. Very happy with it so far. You could argue it's a warranty issue...