Soft rear brake pedal woes…

[AndyCBR]

Hey all I posted this in the sticky thread and it doesn’t appear to be showing up as a new post.

TIA for any advice!


Hello all,

2012 S10 with 34k here and I bled my brakes all around last year before a big trip (it was due). I didn't do anything different than I usually do but I did run the rear reservoir dry but I thought I caught it before any air got in the system. On that trip I ended up getting a soft rear pedal and eventually no rear brakes. I tried bleeding a few times while on the trip only to end up with soft pedal and no rear brakes after a days ride several times. I ended up finishing the trip with no rear brakes.

I didn't know better on the trip to cycle the ABS pump. I do now and I've bled rears and cycled it 6 times and I haven't noticed any air in the lines when bleeding after that first (and subsequent) pump cycles.

Is the only real test to go out and ride and see what happens? Is the ABS activation what introduces air or just the linked brakes and the use of the front brake? How does one rule out the rear master cylinder?

BTW I have had the ABS reservoir compartment fill up with crap about 8 years ago and I had to tear apart the whole back half of the bike then to clean it out (I enlarged the drain holes then) while I was changing a bent subframe (don't ask). Ever since then the box has gotten dusty but not filled up.

A peculiar thing happens when I pump the rear brakes, it's like I can hear a whistling sound from the ABS pump area like something is stroking and moving air. I assume that is the internal pistons and the way dirt gets in the ABS pump?

The bikes been good to me and I have beaten it to death off road so throwing a $1,600 pump in it would be worth it to me but I'm not ready to fire the parts cannon just yet.

Is it true the 2014+ pump is backwards compatible with 2012?

Thanks for any advice!

 

[OldRider]

Unless you just have to have ABS, I would remove the pump, run two separate brakes lines and just have old fashioned front and rear brakes. The S10 has very good brakes with the pump bypassed.

 

[AndyCBR]

Thanks, I really love having ABS and find it works outstanding offroad also. It has saved my bacon a couple of times.

I think I'll use the bypass line trick for the upcoming trip I have next month and then try the outfit in France that does repair. I'm keeping the bike forever so the time and effort would be worth it.

Hope to hear more folks chime in!

Best,
Andy

 

[patrickg450]

you cant remove the pump, the electronics dont like it when it is missing

 

[AndyCBR]

you cant remove the pump, the electronics dont like it when it is missing

I understand. If I were to bypass the rear only I would leave the pump in place.

I'm still curious if the 2014+ pump is backwards compatible with the 2010-2013.

 

[RCinNC]

It looks like the 2013 and up models share the same ABS pump. The part number is 23P-85930-19-00.

The 2012 has a different part number: 23P-85930-09-00. That doesn't mean that it won't fit, only that there was some change made to the pump between 2012 and 2013.

They all retail for $1687.15 at Rocky Mountain ATV. Not a bad price compared to other US parts suppliers, but....Jeez. Web Bike Japan may have a better price, unless shipping costs make it prohibitive. Ebay occasionally lists a used pump for sale.

Check into that place in France that rebuilds pumps before you get your hopes up. Another member here made an inquiry into a place in the UK that does it, and found that they wouldn't work on a pump sent from the US.

 

[AndyCBR]

Yeah I submitted a quote to Web bike Japan but haven’t heard back yet.

Im curious S to what is different between the two parts. Could just be a supplier change since just the suffix is different.

The folks in France let you input a USA address as part of the order form so it looks promising.

I’ve got a trip at the end of the month so if my testing shows the fault is still there I will probably use the bypass line for the rear and just take the pump out and ship it off when I get home in mid September.

 

[Mr. BR]

Just FYI: Here’s the label from a 2013 ABS unit I bought on ebay a few months ago to solve the problem I had with my 2012 bike (ultimately not needed).
The PN is close to what is mentioned above but I can confirm that it did work just fine on my 2012. I ultimately re-installed my original pump unit after I discovered the REAL issue giving me error codes (loose fitting 30A fuse, no voltage to pump).
AndyCBR: you can reach me via PM if you want to consider this unit as a possible replacement if you’re not able to fix your problem.
Mr. BR

 

[AndyCBR]

Thanks Mr. BR, PM sent.

I did see your thread and any reason you believe the fuse holder failed?

My pump runs just fine and cycles well. It’s been exercised a lot when ridden. But I tend to let the bike sit in between big trips.

I’m still not clear on the failure mode with my unit but it seems to be a common theme amongst other users.

 

[Mr. BR]

I spent HOURS going through my shop manual and checking everything I could for my ABS error.... but when I swapped in another pump unit (ebay, 2013 model), I got the same error. What are the chances? I eventually found the 30A fuse was rather loose in its socket and after bending the little fuse blades for a tighter fit, suddenly everything started working... pump cycled, errors cleared. So I re-installed the OEM pump and same thing... everything worked... which is why I no longer need the Ebay pump unit (but I've kept it around as a spare for the past few months).
Regards, Mr. BR

 

[AndyCBR]

So just an out of spec bend/crimp on the fuse holder ears that was making the fit loose?

 

[SHH]

Thanks, I really love having ABS and find it works outstanding offroad also. It has saved my bacon a couple of times.

I think I'll use the bypass line trick for the upcoming trip I have next month and then try the outfit in France that does repair. I'm keeping the bike forever so the time and effort would be worth it.

Hope to hear more folks chime in!

Best,
Andy

Same happened to me last season 2023, i have by passed rear abs and removed fuse for abs pump as the front brake also was spongy. i now have god brakes without abs.
I also would like to repair abs and think i will ship this winter to

ABS Pump Yamaha XT 1200Z Super Ténéré - Repair 24/48H - Lifetime Warranty

Exchange and repair services for your ABS Pump for Réparation bloc abs Yamaha. Delivery under 24/48h ➤ Money back guarantee ✚ Lifetime warranty

diag-engine.com

Does anybody have any experience who is best doing this repair??