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

[DrSpencer]

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

[Coyote]

New abs module. 

[DrSpencer]

New abs module. 

What makes you say that?

Is an ABS module a DIY project, or is a HD Digital Technician Dealer Tool required?

Thanks

[Coyote]

http://harleytechtalk.com/htt/index.php/topic,85858.msg969489.html#msg969489

[Smarty]

Just had a friend in Alabama go thru almost the same thing. His back brakes started getting really hard to push and finally the brakes would start working. It's a 2011 CVO Roadglide. Took it to Harley. My friend works for quality control with Hyundai and as luck with have it, he was at a meeting with the company that makes all the abs systems, for Harley also. Well, Harley had his bike for almost 3 weeks. They wanted the ABS module sent back before they would give him another one. Hmmm?  Anyway, the dealership ended up replacing the whole system including brake lines and rebuilding the calipers. The ABS module problem was the valve on the back brakes. Come to find out, if any part of the ABS fails, it is supposed to shut down, throw codes and show up on the speedo with a check engine light, and all brakes are supposed to work just as normal brakes without ABS. Now, you didn't hear this from me, but rumors thru un-named sources is that sometime in August there will be a huge recall on all ABS systems prior to a certain year. Evidently the program that bypasses the ABS isn't in the system for some reason. This sounds like a big deal to me.

[rbabos]

Just had a friend in Alabama go thru almost the same thing. His back brakes started getting really hard to push and finally the brakes would start working. It's a 2011 CVO Roadglide. Took it to Harley. My friend works for quality control with Hyundai and as luck with have it, he was at a meeting with the company that makes all the abs systems, for Harley also. Well, Harley had his bike for almost 3 weeks. They wanted the ABS module sent back before they would give him another one. Hmmm?  Anyway, the dealership ended up replacing the whole system including brake lines and rebuilding the calipers. The ABS module problem was the valve on the back brakes. Come to find out, if any part of the ABS fails, it is supposed to shut down, throw codes and show up on the speedo with a check engine light, and all brakes are supposed to work just as normal brakes without ABS. Now, you didn't hear this from me, but rumors thru un-named sources is that sometime in August there will be a huge recall on all ABS systems prior to a certain year. Evidently the program that bypasses the ABS isn't in the system for some reason. This sounds like a big deal to me.

Yes but look at the money they saved.
Ron

[markymark]

If there is a recall, look at what they will spend.

[14GuineaPig]

I have a couple of questions for the OP.  Does the brake light come on when you step on the rear rake pedal?  I ask this because the rear brake light switch is a pressure activated switch and if it lights the brake light that would indicate that there is some pressure when the pedal is pressed.  Have you tried bleeding the rear brake at the rear caliper bleeder screw?  If nothing happens there, have you tried bleeding the rear master cylinder at the banjo bolt that connects the brake line to the master cylinder?  I'm just curious if you have pressure at the caliper and at the master cylinder.  If you don't have any pressure at the master cylinder, then I would replace/rebuild the master cylinder.  If the master cylinder is working follow the brake line and check for pressure (bleed) at the ABS module input from the master cylinder and output to the caliper.  From what you stated, "no leaks & fluid is full", I would think the master cylinder is at fault.

[Buffalo]

Is there a chance that somehow the brake fluid used was the wrong type? It is supposed to be Dot 4 only for ABS systems. If Dot 5 was used, it would cause all kinds of problems. Buffalo

[DrSpencer]

I have a couple of questions for the OP.  Does the brake light come on when you step on the rear rake pedal?  I ask this because the rear brake light switch is a pressure activated switch and if it lights the brake light that would indicate that there is some pressure when the pedal is pressed.  Have you tried bleeding the rear brake at the rear caliper bleeder screw?  If nothing happens there, have you tried bleeding the rear master cylinder at the banjo bolt that connects the brake line to the master cylinder?  I'm just curious if you have pressure at the caliper and at the master cylinder.  If you don't have any pressure at the master cylinder, then I would replace/rebuild the master cylinder.  If the master cylinder is working follow the brake line and check for pressure (bleed) at the ABS module input from the master cylinder and output to the caliper.  From what you stated, "no leaks & fluid is full", I would think the master cylinder is at fault.

1) Haven't seen the brake light come on (haven't really looked for it, either). I will check on this.

2) When I changed the brake fluid (15K miles ago), I used a Motive Power bleeder. All my calipers also have Speed Bleeders, so I had a nice firm pedal. Until recently.

3) How to I bleed at the master cylinder, or anywhere else, if the rear brake pedal doesn't allow me to pump up any pressure (it just flops to the floor)?

Thanks

[DrSpencer]

Is there a chance that somehow the brake fluid used was the wrong type? It is supposed to be Dot 4 only for ABS systems. If Dot 5 was used, it would cause all kinds of problems. Buffalo

No, I checked this.

Thanks

[14GuineaPig]

If you can't develop any pressure at the master cylinder then replace/rebuild the master cylinder.  That should be your starting point, not the replacing the abs module.  Also from what I have read when the abs module fails it usually causes a hard pedal or lever that does not move.  That's the opposite of what you are describing.

[Just Nick]

If you can't develop any pressure at the master cylinder then replace/rebuild the master cylinder.  That should be your starting point, not the replacing the abs module.  Also from what I have read when the abs module fails it usually causes a hard pedal or lever that does not move.  That's the opposite of what you are describing.

You Nailed it. We just changed out a bad abs module and it was a hard pedal it was rock hard then it would just brake loose then hard again put a new module on and bled the system hooked it up to the computer for a abs bleed all worked great except the abs light so had to have the dealer use digtal tech to fix the light. but it sounds to me like you need a master cylinder rebuild kit because you can not make pressure at the master cylinder so how can the abs do its job if there is no pressure from the master cylinder

[FSG]

That should be your starting point

how can the abs do its job if there is no pressure from the master cylinder

perzacly   

[DrSpencer]

If you can't develop any pressure at the master cylinder then replace/rebuild the master cylinder.  That should be your starting point, not the replacing the abs module.  Also from what I have read when the abs module fails it usually causes a hard pedal or lever that does not move.  That's the opposite of what you are describing.

You Nailed it. We just changed out a bad abs module and it was a hard pedal it was rock hard then it would just brake loose then hard again put a new module on and bled the system hooked it up to the computer for a abs bleed all worked great except the abs light so had to have the dealer use digtal tech to fix the light. but it sounds to me like you need a master cylinder rebuild kit because you can not make pressure at the master cylinder so how can the abs do its job if there is no pressure from the master cylinder

Fair enough, that's where I'll start.

You say to get a mc rebuild kit, but do they even exist? How much more $ would a new rear mc possibly cost?

Any tips/tricks for installing a new mc on an ABS equipped bike?

Thanks, once more.

[14GuineaPig]

Just one more question ... are you sure the clevis pin (#8) and the push rod (#15) are still connected to the pedal?  The way you say the pedal just flops around had me wondering.

[FSG]

42932-08A KIT,    REPAIR,MSTR CYL,TOURING   MRRP 37.05

[attach=0]

[calif phil]

Just plug the port on the end of the master cylinder to see if it will build pressure.   No need to rebuild it if it's the ABS module. 


Harleypartscheap.com

[sfmichael]

Just plug the port on the end of the master cylinder to see if it will build pressure.   No need to rebuild it if it's the ABS module. 


Harleypartscheap.com

Yes 

[FSG]

Just plug the port on the end of the master cylinder to see if it will build pressure.

by all means the easy things first, but where would the fluid under pressure be going if it was the ABS unit ?

[Coyote]

Just plug the port on the end of the master cylinder to see if it will build pressure.

by all means the easy things first, but where would the fluid under pressure be going if it was the ABS unit ?

There is a cavity but I agree, if if the fluid level never drops (and isn't leaking), then it would seem to be the MC.

[DrSpencer]

Just one more question ... are you sure the clevis pin (#8) and the push rod (#15) are still connected to the pedal?  The way you say the pedal just flops around had me wondering.

Perhaps 'flop' was too strong a description. The linkage you illustrated is intact, but the pedal sinks to the very bottom of its travel, with minimal effort.

(nice pic, BTW).

Thanks

[DrSpencer]

Just plug the port on the end of the master cylinder to see if it will build pressure.   No need to rebuild it if it's the ABS module. 


Harleypartscheap.com

I like your thinking.

I know it's a long shot, but does anyone know what size bolt/thread I would use to plug the mc (saves me a trip to the hardware store)?

Thanks

[FSG]

Pretty sure it's 12mm, but don't use a plug to block the MC, use the banjo bolt with the sealing washers either side of a block of plastic/cutting board the same thickness as the brake line.

[14GuineaPig]

The way you describe what's happening there isn't any pressure.  Remove the banjo bolt completely and hold your finger over the hole and pump the pedal.  If you can't feel any pressure, enough to push the brake fluid past your  finger, replace/rebuild the master.