Possible abs problem
#1
04-29-2011, 09:46 PM
Possible abs problem
Ive read that everybody is happy with there abs and im not too sure mine's working correctly. My front brake seems fine but my rear just seems to relese when it kicks in and it kicks in pretty easy, kinda scarry feeling. Iv'e seen where other riders rarely ever use it and they can feel it pulsating, I cannot feel mine pulsating and im not riding it that hard.(no trail braking) Is this the way this thing is supposed to be or do I have a problem?
this is a 2010 ultra.
this is a 2010 ultra.
#2
04-29-2011, 09:54 PM
If the rear brake is being applied by itself, it would lock very easily. Since you have ABS it senses the impending lock-up, and activates. Since that activation occurs prior to the point a non-ABS motor would actually have a locked wheel, it will impress the rider as requiring very little pedal pressure. The way ABS works is by momentarily releasing the brake, then reapplying it (6 times a second if you care). Since any release of the brake increases braking distance, the feeling you get is that the brake is losing effectiveness.
Use your front brake more, and your rear brake less.
Harris
Denver, CO
www.youtube.com/conedown
Use your front brake more, and your rear brake less.
Harris
Denver, CO
www.youtube.com/conedown
#3
04-29-2011, 09:56 PM
I have an 09 FLHT with ABS and at first I had the same problems but there was a service bulletin with a computer flash that fixed the ABS "overreacting". I thought that the 10's come with the software update already done, but it couldn't hurt to ask or have the dealer check out your ABS system (could be something wrong). Also, as you likely know the rear brake is far less powerful than the front and if your only using the rear sometimes it can almost feel as though its not working fully because its so underpowered compared to the front brake. Don't know if that helps, I'd contact the dealer as its still under warranty.
#5
04-30-2011, 01:33 AM
http://youtu.be/_VaDHxX3kVM
It's a good basic explanation, and worth watching.
Harris
Denver, CO
www.youtube.com/conedown
Last edited by motorlessons; 04-30-2011 at 01:40 AM.
#6
10-08-2011, 08:16 AM
And then you run into this type of ABS issue;
It started with discovering that the rear master cyclinder was empty. Inspected brake hydraulics and didn't notice anything out of the ordinary and that there were no signs of any fluid leakage, either present or past.
The rear brake pads were worn down to (what I would have considered) the point of replacement (not wore out completely but yet the pads were in need of replacement). The rear brake caliper pistons were not extended to the point of causing the M/C fluid level to drop to zero due to fluid displacement.
The brake line from the M/C to the brake switch was rubbed flat on one side (along the frame rail) due to the clutch cable but no leakage was detected. Installed rubber isolator to prevent further damage to line and notified the customer of the line condition.
Re-filled the M/C and opened rear caliper bleeder. Bled out rear brakes with no problem. Air was present till solid fluid came out. Removed pads from rear caliper and opened bleeder to depress caliper pistons with our caliper piston tool (designed to depress all pistons at the same time). Closed bleeder and installed new pads.
Re-confirmed no air in system and topped off M/C. Road tested and all is good. No malfunction, no ABS light on and brakes operating properly along with brake light, when rear brakes are applied.
A few days later, the bike has a brake pedal that is hard as a rock (like stepping on a concrete block). It will not depress and the rear brakes will not activate or even attempt to slow the bike down.
Removed rear brake caliper and verified proper pad fitment and placement of anti rattle clip. All is in order but the brake pedal still would not depress, even with caliper off of its mounting bracket and my fingers between pads, I could feel no pad movement when attempting to press brake pedal down.
In re-examining the hydraulic system, the M/C is full and there is a slight moisture "leakage" of fluid at the rear brake light switch.
Perhaps this is where the original fluid had leaked, causing the fluid loss from the M/C but there were no signs or traces of leakage at this area, nor at any other area of the hydraulics. The brake lights were not operating from the foot brake pedal, whereas just days before they were.
I tested the wiring by jumping the BLS connectors with a paper clip and the brake lights came on.
In scanning the ABS ECU system, the codes that were present were C1095 (Front Brake Swith Interrupt) and C1216 (Rear Brake Light Switch Interrupt). Cleared the system but C1216 returned as an active code.
The ECU as well as the Brake ABS Controller was not recognizing the voltage output (their input) from the rear brake light switch being activated (The ABS controller had no idea that the rear brakes were being applied, even though the Rear Wheel Speed Sensor was greatly differing from the Front Wheel Speed Sensor, when abruptly slowing down yet there were no additional codes other than C1216 - Rear Brake Light Switch)???
Re-installed rear brake caliper and loosened brake line at M/C. Pedal pushed down with little effort and fluid came out of the fitting under pressure as it would normally. Tightened that connection and loosened the fitting, feeding the rear brake hydraulic circuit leading into the ABS HCU and fluid came out under normal brake pressure as the brake pedal was pressed down normally.
The brake hydraulics were operating properly (pressurized fluid) all the way to the ABS HCU. Loosening the hydraulic fitting from HCU which feeds the rear brake caliper and NOTHING - NO Fluid, No Pressure (Brake pedal will not push down and fluid will not exit loose fitting), not even with extreme foot pressure!
Brake fluid hydraulic pressure is not going through the ABS HCU to the rear brakes and the bike has no rear braking action, as well as the brake pedal being hard and unable to be pressed down (at all)?
They way I read it, the valves in the ABS HCU function in 3 ways:
1. Pressure Hold; The apply valve keeps the release valve
closed in order to isolate the slipping wheel when wheel slip
occurs. This holds the pressure steady on the brake so the
hydraulic pressure does not increase or decrease.
2. Pressure Decrease; If the above "pressure hold" does not correct the wheel slip condition, pressure decrease occurs. The apply valve is closed and the release valve is opened and the affected hydraulic circuit is isolated from brake pressure. The excess fluid is stored in the
accumulator until the pump can return the fluid to the master
cylinder or fluid reservoir.
3. Pressure Increase; After the wheel slip is corrected in the above pressure decrease mode, a pressure increase occurs. The ECU increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The apply valve is opened and the release valve is closed. The increased pressure is delivered from the master cylinder and will not exceed the pressure from the master cylinder.
I believe that one of two problems exists. Either there is a serious fault in the ABS controller (no codes indicating difference in speed sensors) and the HCU and that the "Pressure Decrease" valving is stuck closed, thereby isolating (the rear brakes) and not allowing hydraulic pressure from M/C through ABS HCU to allow the rear brake operation, or that the rear brake light circuit hydraulic switch failed and an internal component of this switch travelled through the line and into the HCU and blocking the fluid pressure.
In either event, this is a situation that could have caused serious and disasterous results. Especially since it occured without warning. There should be a fail safe designed in the system to prevent this from ever happening. If the ABS HCU fails or becomes inoperative, the braking system should revert to non ABS braking.
When the ABS Code "C1216" was present, there was no ABS malfuntion indicator light showing as a warning that there was a problem with the ABS. It worked in bulb check and flashed until the bike was ridden a few feet but it did not re-illuminate as a warning.
The rear brake pads were worn down to (what I would have considered) the point of replacement (not wore out completely but yet the pads were in need of replacement). The rear brake caliper pistons were not extended to the point of causing the M/C fluid level to drop to zero due to fluid displacement.
The brake line from the M/C to the brake switch was rubbed flat on one side (along the frame rail) due to the clutch cable but no leakage was detected. Installed rubber isolator to prevent further damage to line and notified the customer of the line condition.
Re-filled the M/C and opened rear caliper bleeder. Bled out rear brakes with no problem. Air was present till solid fluid came out. Removed pads from rear caliper and opened bleeder to depress caliper pistons with our caliper piston tool (designed to depress all pistons at the same time). Closed bleeder and installed new pads.
Re-confirmed no air in system and topped off M/C. Road tested and all is good. No malfunction, no ABS light on and brakes operating properly along with brake light, when rear brakes are applied.
A few days later, the bike has a brake pedal that is hard as a rock (like stepping on a concrete block). It will not depress and the rear brakes will not activate or even attempt to slow the bike down.
Removed rear brake caliper and verified proper pad fitment and placement of anti rattle clip. All is in order but the brake pedal still would not depress, even with caliper off of its mounting bracket and my fingers between pads, I could feel no pad movement when attempting to press brake pedal down.
In re-examining the hydraulic system, the M/C is full and there is a slight moisture "leakage" of fluid at the rear brake light switch.
Perhaps this is where the original fluid had leaked, causing the fluid loss from the M/C but there were no signs or traces of leakage at this area, nor at any other area of the hydraulics. The brake lights were not operating from the foot brake pedal, whereas just days before they were.
I tested the wiring by jumping the BLS connectors with a paper clip and the brake lights came on.
In scanning the ABS ECU system, the codes that were present were C1095 (Front Brake Swith Interrupt) and C1216 (Rear Brake Light Switch Interrupt). Cleared the system but C1216 returned as an active code.
The ECU as well as the Brake ABS Controller was not recognizing the voltage output (their input) from the rear brake light switch being activated (The ABS controller had no idea that the rear brakes were being applied, even though the Rear Wheel Speed Sensor was greatly differing from the Front Wheel Speed Sensor, when abruptly slowing down yet there were no additional codes other than C1216 - Rear Brake Light Switch)???
Re-installed rear brake caliper and loosened brake line at M/C. Pedal pushed down with little effort and fluid came out of the fitting under pressure as it would normally. Tightened that connection and loosened the fitting, feeding the rear brake hydraulic circuit leading into the ABS HCU and fluid came out under normal brake pressure as the brake pedal was pressed down normally.
The brake hydraulics were operating properly (pressurized fluid) all the way to the ABS HCU. Loosening the hydraulic fitting from HCU which feeds the rear brake caliper and NOTHING - NO Fluid, No Pressure (Brake pedal will not push down and fluid will not exit loose fitting), not even with extreme foot pressure!
Brake fluid hydraulic pressure is not going through the ABS HCU to the rear brakes and the bike has no rear braking action, as well as the brake pedal being hard and unable to be pressed down (at all)?
They way I read it, the valves in the ABS HCU function in 3 ways:
1. Pressure Hold; The apply valve keeps the release valve
closed in order to isolate the slipping wheel when wheel slip
occurs. This holds the pressure steady on the brake so the
hydraulic pressure does not increase or decrease.
2. Pressure Decrease; If the above "pressure hold" does not correct the wheel slip condition, pressure decrease occurs. The apply valve is closed and the release valve is opened and the affected hydraulic circuit is isolated from brake pressure. The excess fluid is stored in the
accumulator until the pump can return the fluid to the master
cylinder or fluid reservoir.
3. Pressure Increase; After the wheel slip is corrected in the above pressure decrease mode, a pressure increase occurs. The ECU increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The apply valve is opened and the release valve is closed. The increased pressure is delivered from the master cylinder and will not exceed the pressure from the master cylinder.
I believe that one of two problems exists. Either there is a serious fault in the ABS controller (no codes indicating difference in speed sensors) and the HCU and that the "Pressure Decrease" valving is stuck closed, thereby isolating (the rear brakes) and not allowing hydraulic pressure from M/C through ABS HCU to allow the rear brake operation, or that the rear brake light circuit hydraulic switch failed and an internal component of this switch travelled through the line and into the HCU and blocking the fluid pressure.
In either event, this is a situation that could have caused serious and disasterous results. Especially since it occured without warning. There should be a fail safe designed in the system to prevent this from ever happening. If the ABS HCU fails or becomes inoperative, the braking system should revert to non ABS braking.
When the ABS Code "C1216" was present, there was no ABS malfuntion indicator light showing as a warning that there was a problem with the ABS. It worked in bulb check and flashed until the bike was ridden a few feet but it did not re-illuminate as a warning.
#7
10-09-2011, 12:34 AM
Road Warrior
Trending Topics
#8
10-09-2011, 06:18 PM
Unfortunately I don't have access to a DT. Only have the Motoscan 5650 M/C scanner, which will not perform the ABS HCU valve cycling. Perhaps cycling the valves will free them up and will then allow fluid pressure to the rear wheel.
I would hate to be the owner (or rider) of it though, not ever knowing when or if it would stick again (if indeed that is what is causing the issue) and cause a no stopping condition.
I would hate to be the owner (or rider) of it though, not ever knowing when or if it would stick again (if indeed that is what is causing the issue) and cause a no stopping condition.
#9
03-16-2014, 02:06 PM
It started with discovering that the rear master cyclinder was empty. Inspected brake hydraulics and didn't notice anything out of the ordinary and that there were no signs of any fluid leakage, either present or past.
The rear brake pads were worn down to (what I would have considered) the point of replacement (not wore out completely but yet the pads were in need of replacement). The rear brake caliper pistons were not extended to the point of causing the M/C fluid level to drop to zero due to fluid displacement.
The brake line from the M/C to the brake switch was rubbed flat on one side (along the frame rail) due to the clutch cable but no leakage was detected. Installed rubber isolator to prevent further damage to line and notified the customer of the line condition.
Re-filled the M/C and opened rear caliper bleeder. Bled out rear brakes with no problem. Air was present till solid fluid came out. Removed pads from rear caliper and opened bleeder to depress caliper pistons with our caliper piston tool (designed to depress all pistons at the same time). Closed bleeder and installed new pads.
Re-confirmed no air in system and topped off M/C. Road tested and all is good. No malfunction, no ABS light on and brakes operating properly along with brake light, when rear brakes are applied.
A few days later, the bike has a brake pedal that is hard as a rock (like stepping on a concrete block). It will not depress and the rear brakes will not activate or even attempt to slow the bike down.
Removed rear brake caliper and verified proper pad fitment and placement of anti rattle clip. All is in order but the brake pedal still would not depress, even with caliper off of its mounting bracket and my fingers between pads, I could feel no pad movement when attempting to press brake pedal down.
In re-examining the hydraulic system, the M/C is full and there is a slight moisture "leakage" of fluid at the rear brake light switch.
Perhaps this is where the original fluid had leaked, causing the fluid loss from the M/C but there were no signs or traces of leakage at this area, nor at any other area of the hydraulics. The brake lights were not operating from the foot brake pedal, whereas just days before they were.
I tested the wiring by jumping the BLS connectors with a paper clip and the brake lights came on.
In scanning the ABS ECU system, the codes that were present were C1095 (Front Brake Swith Interrupt) and C1216 (Rear Brake Light Switch Interrupt). Cleared the system but C1216 returned as an active code.
The ECU as well as the Brake ABS Controller was not recognizing the voltage output (their input) from the rear brake light switch being activated (The ABS controller had no idea that the rear brakes were being applied, even though the Rear Wheel Speed Sensor was greatly differing from the Front Wheel Speed Sensor, when abruptly slowing down yet there were no additional codes other than C1216 - Rear Brake Light Switch)???
Re-installed rear brake caliper and loosened brake line at M/C. Pedal pushed down with little effort and fluid came out of the fitting under pressure as it would normally. Tightened that connection and loosened the fitting, feeding the rear brake hydraulic circuit leading into the ABS HCU and fluid came out under normal brake pressure as the brake pedal was pressed down normally.
The brake hydraulics were operating properly (pressurized fluid) all the way to the ABS HCU. Loosening the hydraulic fitting from HCU which feeds the rear brake caliper and NOTHING - NO Fluid, No Pressure (Brake pedal will not push down and fluid will not exit loose fitting), not even with extreme foot pressure!
Brake fluid hydraulic pressure is not going through the ABS HCU to the rear brakes and the bike has no rear braking action, as well as the brake pedal being hard and unable to be pressed down (at all)?
They way I read it, the valves in the ABS HCU function in 3 ways:
1. Pressure Hold; The apply valve keeps the release valve
closed in order to isolate the slipping wheel when wheel slip
occurs. This holds the pressure steady on the brake so the
hydraulic pressure does not increase or decrease.
2. Pressure Decrease; If the above "pressure hold" does not correct the wheel slip condition, pressure decrease occurs. The apply valve is closed and the release valve is opened and the affected hydraulic circuit is isolated from brake pressure. The excess fluid is stored in the
accumulator until the pump can return the fluid to the master
cylinder or fluid reservoir.
3. Pressure Increase; After the wheel slip is corrected in the above pressure decrease mode, a pressure increase occurs. The ECU increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The apply valve is opened and the release valve is closed. The increased pressure is delivered from the master cylinder and will not exceed the pressure from the master cylinder.
I believe that one of two problems exists. Either there is a serious fault in the ABS controller (no codes indicating difference in speed sensors) and the HCU and that the "Pressure Decrease" valving is stuck closed, thereby isolating (the rear brakes) and not allowing hydraulic pressure from M/C through ABS HCU to allow the rear brake operation, or that the rear brake light circuit hydraulic switch failed and an internal component of this switch travelled through the line and into the HCU and blocking the fluid pressure.
In either event, this is a situation that could have caused serious and disasterous results. Especially since it occured without warning. There should be a fail safe designed in the system to prevent this from ever happening. If the ABS HCU fails or becomes inoperative, the braking system should revert to non ABS braking.
When the ABS Code "C1216" was present, there was no ABS malfuntion indicator light showing as a warning that there was a problem with the ABS. It worked in bulb check and flashed until the bike was ridden a few feet but it did not re-illuminate as a warning.
The rear brake pads were worn down to (what I would have considered) the point of replacement (not wore out completely but yet the pads were in need of replacement). The rear brake caliper pistons were not extended to the point of causing the M/C fluid level to drop to zero due to fluid displacement.
The brake line from the M/C to the brake switch was rubbed flat on one side (along the frame rail) due to the clutch cable but no leakage was detected. Installed rubber isolator to prevent further damage to line and notified the customer of the line condition.
Re-filled the M/C and opened rear caliper bleeder. Bled out rear brakes with no problem. Air was present till solid fluid came out. Removed pads from rear caliper and opened bleeder to depress caliper pistons with our caliper piston tool (designed to depress all pistons at the same time). Closed bleeder and installed new pads.
Re-confirmed no air in system and topped off M/C. Road tested and all is good. No malfunction, no ABS light on and brakes operating properly along with brake light, when rear brakes are applied.
A few days later, the bike has a brake pedal that is hard as a rock (like stepping on a concrete block). It will not depress and the rear brakes will not activate or even attempt to slow the bike down.
Removed rear brake caliper and verified proper pad fitment and placement of anti rattle clip. All is in order but the brake pedal still would not depress, even with caliper off of its mounting bracket and my fingers between pads, I could feel no pad movement when attempting to press brake pedal down.
In re-examining the hydraulic system, the M/C is full and there is a slight moisture "leakage" of fluid at the rear brake light switch.
Perhaps this is where the original fluid had leaked, causing the fluid loss from the M/C but there were no signs or traces of leakage at this area, nor at any other area of the hydraulics. The brake lights were not operating from the foot brake pedal, whereas just days before they were.
I tested the wiring by jumping the BLS connectors with a paper clip and the brake lights came on.
In scanning the ABS ECU system, the codes that were present were C1095 (Front Brake Swith Interrupt) and C1216 (Rear Brake Light Switch Interrupt). Cleared the system but C1216 returned as an active code.
The ECU as well as the Brake ABS Controller was not recognizing the voltage output (their input) from the rear brake light switch being activated (The ABS controller had no idea that the rear brakes were being applied, even though the Rear Wheel Speed Sensor was greatly differing from the Front Wheel Speed Sensor, when abruptly slowing down yet there were no additional codes other than C1216 - Rear Brake Light Switch)???
Re-installed rear brake caliper and loosened brake line at M/C. Pedal pushed down with little effort and fluid came out of the fitting under pressure as it would normally. Tightened that connection and loosened the fitting, feeding the rear brake hydraulic circuit leading into the ABS HCU and fluid came out under normal brake pressure as the brake pedal was pressed down normally.
The brake hydraulics were operating properly (pressurized fluid) all the way to the ABS HCU. Loosening the hydraulic fitting from HCU which feeds the rear brake caliper and NOTHING - NO Fluid, No Pressure (Brake pedal will not push down and fluid will not exit loose fitting), not even with extreme foot pressure!
Brake fluid hydraulic pressure is not going through the ABS HCU to the rear brakes and the bike has no rear braking action, as well as the brake pedal being hard and unable to be pressed down (at all)?
They way I read it, the valves in the ABS HCU function in 3 ways:
1. Pressure Hold; The apply valve keeps the release valve
closed in order to isolate the slipping wheel when wheel slip
occurs. This holds the pressure steady on the brake so the
hydraulic pressure does not increase or decrease.
2. Pressure Decrease; If the above "pressure hold" does not correct the wheel slip condition, pressure decrease occurs. The apply valve is closed and the release valve is opened and the affected hydraulic circuit is isolated from brake pressure. The excess fluid is stored in the
accumulator until the pump can return the fluid to the master
cylinder or fluid reservoir.
3. Pressure Increase; After the wheel slip is corrected in the above pressure decrease mode, a pressure increase occurs. The ECU increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The apply valve is opened and the release valve is closed. The increased pressure is delivered from the master cylinder and will not exceed the pressure from the master cylinder.
I believe that one of two problems exists. Either there is a serious fault in the ABS controller (no codes indicating difference in speed sensors) and the HCU and that the "Pressure Decrease" valving is stuck closed, thereby isolating (the rear brakes) and not allowing hydraulic pressure from M/C through ABS HCU to allow the rear brake operation, or that the rear brake light circuit hydraulic switch failed and an internal component of this switch travelled through the line and into the HCU and blocking the fluid pressure.
In either event, this is a situation that could have caused serious and disasterous results. Especially since it occured without warning. There should be a fail safe designed in the system to prevent this from ever happening. If the ABS HCU fails or becomes inoperative, the braking system should revert to non ABS braking.
When the ABS Code "C1216" was present, there was no ABS malfuntion indicator light showing as a warning that there was a problem with the ABS. It worked in bulb check and flashed until the bike was ridden a few feet but it did not re-illuminate as a warning.
Came across your post and found it to be very helpful. I recently had the same malfunction / failure on my 2009 FLHTCU except it was the front brake. The front brake lever was rock solid.
Recently I called my local H.D. dealer to pick up my bike from my home for a flat rear tire. When the truck showed up for my bike, I began to back my bike out of the garage. Immediately I noticed there was something wrong with front brake lever. It was impossible to move the brake lever at all. I even tried squeezing it with both hands, still nothing. I brought this to the attention of the driver / service tech. He said he would make sure it was addressed.
Three weeks later when I picked up my bike from the dealer, I asked the service manager what they had found with the front brake. I was told, they couldn't find anything wrong with it. I went to get on my bike to leave and I found the front brake lever pull was considerably harder than normal. I went back inside and asked the service manager about it and was told "yea it is somewhat harder than normal but it is functional". When I got back home, I compared it to the front brake pull on my 05 FLSTCI. Immediately, I felt there was definitely something wrong.
A few days later I went to move my bike out of the garage and just as before, the front brake lever was rock solid. I called the dealer, scheduled to have the bike picked up. I received a call from the dealer 2 days later and they said the ABS unit was faulty.
#10
03-16-2014, 03:45 PM
