ABS - help needed

[The Gecko_imp]

I know there is quite a bit of insight scattered over many posts, but it is hard to apply this knowledge to my (recent) problem. Any help would be really welcome. Here is what happens on my m/c:

- turn ignition on : ABS light on as expected
- start engine and roll : light goes off, as expected
- riding : no issues
However, when you brake hard enough with the rear brake the wheel blocks and the ABS light comes on and stays on until you turn the ignition off,
- I have not tried with the front brakes.

This seems to indicate that the valve inside the ABS unit (which is supposed to release the pressure and open up the brake momentarily) does not operate when needed BUT the unit cannot tell when the self test is run at start. Would you have any idea what could be wrong ? or what I can do before taking her to the dealer and spend a fortune ?
Thanks !!

 

[Lord Popgun]

I just got back from a trip and am just too tired to delve into this in detail.

However, First check the speed sensor gaps on both wheels for proper spacing and that the rings are not bent or damaged. Make sure there are no bugs, dirt, etc. stuck in the sensor gap or any of the slots.

Also the book says DO NOT remove any ABS connectors with power applied. Make sure the ignition is off.

 

[max]

Gecko we would like some more info;

Did the wheel lock up and stayed locked?

Did the situation clear itself?

And the last time the fluid in the system was replaced?

Reading on the web it occurs to me that abs may pose more problems at the wrong time than the advantages it has if left to "fend for itself" as time passes and parts start to corrode due to lack of use.

Here is one of the better diagrams on the workings of the system;



And a picture of how these units look nowadays;



My only bike with abs is the cb1000r and i test both brakes regularly on a flat grassy surface at slow speed, i also have a special bleed nipple which has an adjustable outflow and i use this to expel enough new fluid to replace the pump body's internal old fluid which mixes downstream with the new fluid when the abs is made to operate.
After the excersize i replace the fluid again to make sure it has exited the system.

All this would have made better and more reliable if there was an abs cycle built into the system from the factory to replace the fluid inside the modulator body.

The abs selfcheck includes a continuity test for all solenoids and the pump to ensure all parts are not open circuit and the sensors are working properly when the vehicle starts to move above a set speed.

But these tests do not include if the parts are stuck and the user is unaware of this until.......!

 

[The Gecko_imp]

@max, to your questions:
1) rear wheel locked up briefly, back turning again when I released the rear brake pedal - but abs definitely didn’t kick in,
2) problem remains (as described before), comes back next day with the same symptoms,
3) I replaced all fluids 2 months ago, but didn’t know how to make sure the fluid in the abs unit gets flushed, chances are some of the fluid got flushed, and some is as old as from 2017.
Thanks for the diagram !

 

[Gone in 60]

Hmmm, one of my BMWs did this. It turned out to be an internal pressure sensor inside the ABS unit, and not something that was serviceable without replacing the ABS unit itself.

Hope your problem is more easily resolved.

 

[The Gecko_imp]

Thanks for the hint anyway, Gi60 !

I just got back from a trip and am just too tired to delve into this in detail.

However, First check the speed sensor gaps on both wheels for proper spacing and that the rings are not bent or damaged. Make sure there are no bugs, dirt, etc. stuck in the sensor gap or any of the slots.

Also the book says DO NOT remove any ABS connectors with power applied. Make sure the ignition is off.

Thanks LP, I don't see any dirt on the sensors and spacing looks good. Also wonder whether such causes wouldn't be detected during the self-test after turning the engine on and rolling. Any thoughts ?

 

[max]

Gecko thanks for the answers and flushing the fluid so recently, this helps to pinpoint the repair;

The thing i would do is find a large enough grassy or similar area and gently operate ( excersize ) both brakes ( to operate and feel the abs pulse ) and see if you can un-seize the valve in question, doing this repeatedly could just restore the functionality and make things work as they should.

The valves have spring loaded solinoids, these are coils which have moveable soft steel cores ( pintles ) which move from their rest position when the coil is switched on and the resulting magnetic force pulls the pintels from the seat , open the valve and allow fluid to flow, much like fuel injectors or the water valve in a washing machine;


And with repetitive activation of the coil the pintle may just free itself and return to normal operation.

Definitely worth a try

 

[Lord Popgun]

Thanks for the hint anyway, Gi60 !

I just got back from a trip and am just too tired to delve into this in detail.

However, First check the speed sensor gaps on both wheels for proper spacing and that the rings are not bent or damaged. Make sure there are no bugs, dirt, etc. stuck in the sensor gap or any of the slots.

Also the book says DO NOT remove any ABS connectors with power applied. Make sure the ignition is off.

Thanks LP, I don't see any dirt on the sensors and spacing looks good. Also wonder whether such causes wouldn't be detected during the self-test after turning the engine on and rolling. Any thoughts ?

Thanks LP, I don't see any dirt on the sensors and spacing looks good. Also wonder whether such causes wouldn't be detected during the self-test after turning the engine on and rolling. Any thoughts ?
I would think it would be detected and set the light or cause it to flash. But we had a user with a weird ABS problem that was caused by a bent rear ring.

I threw those out as they are fast and easy to check before getting into it. A quick glance at the book this morning said to jumper the ABS diag. plug and see the actual code. And I was hoping Max would get into that.

 

[The Gecko_imp]

@max, would you agree with another post/er some time ago, saying that (if anything else fails) flushing the fluid AND exercising (as you suggest) AND do both a few more times is worth a try too ?
@LP thanks a lot for the clarification

@anybody owning a service manual for the 2017EX : could you contact me by PM, please !! Not asking for anything illegal, just need to know if the ABS system is covered in greater detail than in the older manual which I have.

 

[peterbaron]

2 PM sent

 

[max]

There are more ways than one to deal with this, the most aggressive being removing the electronic part and moving the pintels with a strong magnet in order to free it up, that is quite advanced but could be done.

Definitely worth trying the excersize way because of the non-invasive nature of the approach and something i would do first.
Assuming the abs has worked until recently so the stickyness should be minor.

Have you tested the front brake abs activity?

Since the pintels are pushed in position with a spring i would not try to tap the housing in an attempt to loosen them up .

This situation is actually the lesser of a faulty system, someone else reported that the brake actually failed to operate if i remember correctly.

It also seems that Honda's advice to basically flush the fluid and not worry about the abs modulator ( they don't provide instructions as far as i know but i could be wrong here ) is sometimes not sufficient to prevent a situation like yours.

Sorry if i overdo it with the instructions, you seem quite adequately familiar with bikes but it may help someone else if i tell the whole story; cheers

 

[The Gecko_imp]

@max, you ARE a genius !!!!
today went on wet grass (with care), again wheels blocked and ABS light comes on as before, rear and front, all the same.
tried a few more times - faster, heavier braking, no effect at all.
Found a different spot in the grass with a little more gravel visible and less dew visible. Tried the rear first, but no improvement.
Back to the front, speed up to 15 may be 20mph, heavy braking. Repeat ... only after 6th or 7th repetition I hear the ABS kick in on the front AND the light stays off. Try again, try the rear. The problem is gone.

If anybody has that problem and reads this thread, be careful ! You want boots on with very good traction and hold that handle bar straight. Otherwise your ABS test will end "where no man has ever wanted to go before".

Will watch if it stays like this over the next few rides. For now all I can say : Kisses to the moon and back to NZ !!!

 

[Nachodaddy]

Awesome! Max is the MAN! Great work Gecko and Max.

 

[max]

That makes me smile Gecko, thanks for your perseverance and a very complete description of what happened, i should have mentioned the straight line aspect of the excersize, thanks for emphasizing that.

Found it interesting that both wheels reverted to normal operation:huh::huh:

So the question is; was the front wheel also affected by this fault??

Suspect some corrosion could be at play here so if it was me i would excersize the system some more and replace the fluid again and watching the fluid that comes out of the line closely to see if there is anything to indicate what happened.

Because of how the system operates the fluid inside the abs modulator does not get replaced but rather moved back and forth in the system and mixes in with the fresh fluid in the lines as the abs pulses so the more it pulses the more the fluid mixes and so replaces the old static modulator fluid.

Very nice outcome, and thanks for your much appreciated feedback

 

[GoldOxide_imp]

@max, you ARE a genius !!!!
today went on wet grass (with care), again wheels blocked and ABS light comes on as before, rear and front, all the same.
tried a few more times - faster, heavier braking, no effect at all.
Found a different spot in the grass with a little more gravel visible and less dew visible. Tried the rear first, but no improvement.
Back to the front, speed up to 15 may be 20mph, heavy braking. Repeat ... only after 6th or 7th repetition I hear the ABS kick in on the front AND the light stays off. Try again, try the rear. The problem is gone.

If anybody has that problem and reads this thread, be careful ! You want boots on with very good traction and hold that handle bar straight. Otherwise your ABS test will end "where no man has ever wanted to go before".

Will watch if it stays like this over the next few rides. For now all I can say : Kisses to the moon and back to NZ !!!

Congratulations Gecko!

 

[Cormanus]

Elegant diagnosis, Max. And bonus marks for perseverance, Gecko.

 

[the Ferret]

Nice work you two

 

[The Gecko_imp]

That makes me smile Gecko, thanks for your perseverance and a very complete description of what happened, i should have mentioned the straight line aspect of the excersize, thanks for emphasizing that.

Found it interesting that both wheels reverted to normal operation:huh::huh:

So the question is; was the front wheel also affected by this fault??

Suspect some corrosion could be at play here so if it was me i would excersize the system some more and replace the fluid again and watching the fluid that comes out of the line closely to see if there is anything to indicate what happened.

Because of how the system operates the fluid inside the abs modulator does not get replaced but rather moved back and forth in the system and mixes in with the fresh fluid in the lines as the abs pulses so the more it pulses the more the fluid mixes and so replaces the old static modulator fluid.

Very nice outcome, and thanks for your much appreciated feedback

Now looking at the diagram again, this means Honda doesn’t use units which comply with that diagram. Since early abs models of the CB1100 had combined brakes ??? didn’t they .... could it be that Honda simply made a little change in 2014 which disabled that mode, but there is still some x-talk between front and rear ?

 

[Lord Popgun]

The 2013 models with C-ABS have different plumbing. It is the only model with C-ABS.

 

[max]

Once again a very clear explanation of what happened, i had an idea from your earlier post that the front was also affected but this cleared it up,.

Don't want to guess or interpret if i can help it and your explanation is excellent.

Ferret can explain this better than i can but i can't remember a combined braking system on our cb1100's.
( edit ) and thanks very much Lord Popgun for the clarification ).

The abs units have become smaller over the years but the working principle has always been the same and for the ones interested here is a 1,5 h long video of ZAM's channel, he completely takes an abs unit apart and explains ( in fluent German ) what happened inside when the unit from a 2006 cbf1000 with over 200.000 km and was removed in a working state but left disconnected for some years.

The electronic unit gets separated at 12 minutes, shows the pintel valves, the pump at 24 minutes and the pintels are operated at 1 h 12 minutes, i watched the entire video several times but i understand german well enough to grasp the very detailed explanation and have a lot of curiosity as well, he is about the best in explaining and repairing mostly Honda's and i have learned a great deal from his channel.

And so i am very grateful for all your precise input because we can all learn from it.

Thank you Gecko!