2011 FLHX w/ABS: Rear Brake Pedal Goes to Floor, Doesnt Stop. Where Do I Begin?

[Jaycee1964]

One question.  If the bike is turned off and battery disconnected does the brake pedal still go all the way down?  I too think it's a bad brake master....  But....

[Karl H.]

...When coasting, if I stab the pedal all the way to the floor, I can hear the ABS chattering, like it normally would...

I bet it's a faulty ABS unit! Otherwise why would the ABS valves chatter while the rear wheel rotates freely? What you describe seems to be the typical behavior of the brake pedal when the ABS unit is switched into service/bleeding mode by my Twin Scan III (or likely any other service computer). The complete volume of the master cylinder is taken by the accumulator 2 while valve V4 is open. Whenever the pedal is released (in order to press it again) the accumulator gets drawn empty by the rotating pump and the pedal can be stabbed to the floor again.



Karl

[14GuineaPig]

...When coasting, if I stab the pedal all the way to the floor, I can hear the ABS chattering, like it normally would...

I bet it's a faulty ABS unit! Otherwise why would the ABS valves chatter while the rear wheel rotates freely? What you describe seems to be the typical behavior of the brake pedal when the ABS unit is switched into service/bleeding mode by the Twin Scan III (or DigiTec). The complete volume of the master cylinder is taken by the accumulator 2 while valve V4 is open. Whenever the pedal is released (in order to press it again) the accumulator gets drawn empty by the rotating pump and the pedal can be stabbed to the floor again.



Karl

First, thanks for posting the diagram and an explanation of how the abs module works.  Do you think V4 could be stuck in an open position?  If the bike was OFF and the main fuse removed do you think that would allow the rear brake to work?  I'm asking because I'm trying to understand how the abs works.
If it is a failure of the abs module it would be the first failure that I have read about where the pedal/lever was not "frozen" or "rock hard".  If the abs failed it also did not revert to standard braking as it should and it did not light the abs indicator light according to the OP.  If the abs was serviced as recommended and it failed in this manner it should be reported to the NHTSA.  I'm waiting to hear what the OP finds.

[wholehog]

   I don't understand how Harley can get away with an ABS failure affecting the proper operation of the foundation braking system......that is like dangling a bloody body in front of a plaintiff's lawyer

somebody explain that.....

[Karl H.]

...If the bike was OFF and the main fuse removed do you think that would allow the rear brake to work?...

That's a good idea! It seems to be an electronical fault for me (not a stuck valve) because the pulsation can be heard. The hydraulic unit itself is basically fale safe. If the ABS-ECU ist off 12V power, the hydraulic valves - if not stuck - should allow a normal brake operation. So drawing the fuse should be a good test here! When the pedal is firm after drawing the fuse it's definitely a fault in the ABS-ECU.

Karl

[DrSpencer]

Finally got a chance to get back to the bike today.

Before turning on the ignition, I verified that the rear brake pedal linkage was properly connected (it was).

I then gave the rear brake pedal a few quick pumps with my hand, and I felt some slight pressure building. The pedal didn't go straight to the floor, as previously.

I then decided to check for any codes, and found the following:

C1094 [H] ABS: 'Front brake switch always on'
C1095 [H] ABS: 'Front brake switch open'
C1314 [H] ABS: 'Rear brake switch always on'
C1216 [H] ABS: 'Rear brake switch open'
B1155 [H] TSSM: 'Neutral switch input shorted to ground'

I cleared the codes and let the bike warm up.

The rear brake pedal responded positively to being 'pumped up'. It didn't seem to be as firm as it once might have been, but maybe I'm now being critical.

Went for a ride, and the rear brake operated as it should. ABS engaged when it was supposed to, brake light did not come on when brakes (front or rear) were applied, and it seemed to stop fine.

Rear brake pedal still seems a little softer than I remember..........

I should mention, the only thing that was done to this bike before the rear brake failed was I put on a new Fuel Moto 2-1-2 Jackpot head pipe (which replaced an identical FM head pipe that was cracked). I can't see how this would have any bearing on the rear brake failure, but I thought I should mention it.

Can anyone comment on today's discovery?

Thanks

[Karl H.]

Four inconsistent/conflicting ABS ECU related electrical failure codes! The ABS ECU monitors the brake switch inputs and sets the codes if required. It also uses the brake signals "to enhance the ABS performance and operation" (according to the manual). I still think it was a the ABS ECU not working correctly. 

Karl

[moose]

just happened to my buds bike a few weeks ago no rear pedal right down

wound up an abs unit replaced by the dealer.   we cut the old one apart and sure enough one of the pistons was jammed.  and it did not by pass the abs and work manually

[wholehog]

just happened to my buds bike a few weeks ago no rear pedal right down

wound up an abs unit replaced by the dealer.   we cut the old one apart and sure enough one of the pistons was jammed.  and it did not by pass the abs and work manually

gee....I thought the ABS was supposed to save your life, not kill you 

[DrSpencer]

I need some advice.

Should I install a new ABS ECU myself, then bring it to the Dealer and have hem bleed it with the Digital tech?

or

Should I just drop it off at the Dealer and have them do everything?

What would you do?

Thanks

[Coyote]

You can change the module easy enough. Then bleed it the best you can and take it to someone with the ability to do a digital bleed on it. There are several tools now to do this beside the dig tech.

[DrSpencer]

You can change the module easy enough. Then bleed it the best you can and take it to someone with the ability to do a digital bleed on it. There are several tools now to do this beside the dig tech.

Besides the ABS ECU module, are there any other parts I should order for this project?

Thanks

[Coyote]

You can change the module easy enough. Then bleed it the best you can and take it to someone with the ability to do a digital bleed on it. There are several tools now to do this beside the dig tech.

Besides the ABS ECU module, are there any other parts I should order for this project?

Thanks

No it's straight forward. you need to unbolt all 4 banjos. Then remove the rubber isolated mounting bolts. Remove the entire assemble and swap out the electronics on the bench. Assembly is just the reverse.  I made sure to have my vacuum hose next to each banjo as I removed them to clean up any fluid left from emptying the lines. Kept things neater that way.

[Smarty]

2011 Street Glide w/ABS, ~30K miles.

The rear brake abruptly stopped working. Pedal goes all the way down, but nothing, no stopping power at all.

The pedal cannot be 'pumped back up' to any level of firmness, whatsoever. Nothing but mush throughout the whole range of travel.

When coasting, if I stab the pedal all the way to the floor, I can hear the ABS chattering, like it normally would.

Master cylinder is full (brake fluid was changed at 15K miles), and no signs of fluid loss at the caliper, or anywhere else along the chain.

I should mention, this bike was issued a recall for some type of rear brake switch (located near the trans cover) to be replaced. I have not yet had the recall performed by the Dealer.

Where should I start?

Thanks

Just had a buddy in Alabama have close to the same thing happen to him. After an indy looked at it, he took it to Harley. Harley ended up covering everything since it was the abs. My understanding is the abs is supposed to be built where if it fails, you still have regular brakes. This was not the case with his bike. It's worth a shot. If need be, I can give you his number and name in an pm and get you two together on what happened exactly.

[rbabos]

Only a matter of time before MoCo get's sued over this. Not having a bypass for braking is clear negligence, any lawyer can have a field day with the design short cut. Plenty of internet reference material to prove the point also.  Like, who in their right mind designs a braking system like that, where if the ABS fails, so could braking. Sadly in some cases the flaw will show up when stopping is a matter of life and death.
Ron

[Ohio HD]

I know there are mixed players on the ABS / non ABS subject. The fact that HD's system is less than optimum, and in a few cases seen to be unsafe, I decided that one of the changes for my '09 will be removing the ABS. As they function today, I'm not sure there is much benefit to them being on there at all.


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