No rear brakes

[Supertanker]

Hi All,

I finally got a chance to start trouble shooting my ABS light on/no rear brakes issue (I’m a retail store manager so free time ain’t much) but before I start taking things apart I thought I’d ask a couple of questions on the forum in the hope that people smarter than myself can save me from myself LOL.

Ok so the issue is that my ABS light comes on the minute I press the rear brake lever plus I have zero rear brakes. There’s no pressure there at all. My front brakes are working perfectly.

I tried bleeding my brake system (old school way with a bottle and pipe). Front right, front left and then the rear. No issues with the front but zero brake fluid comes out the rear bleed nipple. I can’t get the level of the brake fluid in the rear brake reservoir to drop at all when I pump the rear brake lever during bleeding.

I then tried to bleed the rear using a vacuum bleeder. Still can’t get any brake fluid out the rear nipple.

I don’t have a diagram of the inside workings of the ABS unit but I’m assuming that the brake pressure sensors electronically speak to the ABS ECU and then there’s a bunch of solenoids and valves and a pump in there that manages the hydraulics and hydraulically obviously front is joined to the rear.

I tried to cycle the ABS unit by using the jumping with the wire trick (also from this forum) and it cycles once only (one click) and then stops (not sure if that’s normal?)

So first questions is (before I go straight to doing the ABS bypass trick that I read about here) – why can’t I bleed the rear? Is my rear master cylinder shot or can the ABS unit be preventing the bleed? (Huge air lock maybe?) Its not as though the bike was standing in a puddle of brake fluid (I don’t see any fluid leaks anywhere).

Are my symptoms indicative of master cylinder or ABS unit failure? (I'm not sure whether the ABS unit can create the zero rear brake symptom) or something else maybe?

It just occurred to me now - do I need to switch the ignition on if I'm trying to bleed the rear (to activate the ABS unit and get the air out of there if that's the issue)?

Any advice/pointers/tips appreciated - before I start ripping things apart.

Regards

Wayne

 

[Jlq1969]

It does not matter that it is in ignition to bleed….with respect to the “interior” of the ABS module, yes…there are valves, sensors and selonoids….
Respect to the failure of the module, there are two types…1) without b rear brake and the pedal goes to the floor without braking...2) without rear brake because the pedal is hard as a rock...either of the two failures leaves you without rear brake...master cylinder failure is less common…
I understand from what you say, that you press the rear lever, and it moves down, but it does not push fluid to the rear caliper... that would indicate that "inside the ABS module", the valve that interrupts the pressure between the master cylinder and The caliper is closed, and the fluid makes a buckle backwards, to an internal reservoir, which then that liquid is pumped towards the line, when the electric motor is turned on. (that's why you feel the lever going back)……. You would have to keep cycling the abs, and purging and coming back. cycle…….and see what happens, before ignoring the module with a by pass…….

PD; But I never read that those who return from the dead would tell what it was like (if there were women, if there were motorcycles, if you had to work, if you could do everything you wanted... or if it was very hot)... whenever they came back, …they said they saw only a “small white light at the end of the tunnel”…

 

[Supertanker]

OK thanks for your response. I'm going to try open both front and back brake fluid reservoirs and vacuum bleed from the rear nipple and cycle the ABS simultaneously to see whether I can get the ABS valves to open for the rear brake end.

 

[Highwayman]

I'd definitely be focused on the ABS portion.... The light and the fact even with a bad MC you will still be able to pull fluid through the bleeder with a vacuum.... Spending more time on bleeding seems like wasting more time and wont accomplish anything. Look for codes and start diagnostics off the flowchart. Id bet its a bad ABS unit.

 

[MattR]

Uk company Hel Perfomance produce brake line kits for most bikes. They also sell ABS delete kits. Can’t see one listed for S10 but they are very good at making up lines to your requirements


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[Supertanker]

Thanks everyone. Yup - ABS is knackered. I will bypass it as soon as I've collected all the bobs and bits for the job.

 

[MattR]

I spoke to Shaun Norcott at Hel Performance. He told me they would produce the lines for S10 ABS delete if there is a demand for it but pointed out that it will bring up a fault light on the dash


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[Bmwdumptruck]

Why not just get a second hand replacement abs? Surely that would be a much simpler solution that leaves the bike working as designed.
How old is the bike? The only time I‘ve had a similar issue was an old GS that refused to let me bleed the front brakes, turned out to be old knackered hoses. Odly they still worked, but wouldn’t allow me to bleed fresh fluid through. Any bike over 10 years old with original rubber hoses could be in need of new ones. Pretty sure service shedule mentions it even sooner.

 

[MattR]

Personally that’s what I would do but I think they are hard to find and expensive so I guess some folk rather ditch the abs instead.


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[bimota]

trouble is tho ebay is really the only place to get a second hand abs pump and there stupid money most of the time would you camble your getting a working one off there

rob

 

[bimota]

if mine goes, i,ll send it here for repair

may be handy company UK advertising ABS module repair

https://www.carmoelectronics.co.uk/index.php?main_page=index&cPath=493_6257_6267&fbclid=IwAR1rkPjlhIWHgKJIt4HXenlFDzai5_TJfcuYVgYqZv42qLwyzg0jjEQhx3A rob

yamahasupertenere.com

rob

 

[Supertanker]

Hi guys - basically its all about turnaround time and cost. For me to send the ABS module to the other side of the planet (I'm on the tip of Africa) and then get raped with the rand/USD/British pound exchange rate just isn't worth it. Bypassing is my quickest most cost effective solution (if I was American or British I'd consider repairing/replacing)

 

[cyclemike4]

I have always had some sort of issue with the linked brakes since my bike was new. Not sure if they are all like that or not but I really don't like it. If I use the rear brake first it has a longer travel before activating the brake than it does if I hit the front brake first. the brake always works but if you are going off memory and feel it will through you off a bit during hard braking. I have never liked that and can't get it out. With that being said I do like the ABS on this bike. This is the only machine I have ever owned two wheeled or four wheeled that I actually like the ABS. If it were not for that I would have bypassed it years ago. If something happens to it and I have any more issues it will be by passed. I would probably look into buying a new unit if it was available and I could afford it at the time.