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Discussion Starter · #21 ·
The symptoms you described do not relate to air in the system. Sounds like an intermittent so I would look at the main big connector on the ABS and look for corrosion there. Normally a wig wag of the lights at 1 hz is an indication of low fluid in the rear dual reservoir, but that usually does not lead to a loss of brake power.
I am in agreement about this issue being an intermittent problem and I was also thinking it is electrical in nature. I took off the big connector on the ABS tonight and I was really hoping to find corrosion on the contacts so I would know I found the problem. But, when I pulled the connector off everything was nice and dry and I did not see any corrosion at all. I did slide the connector on and off several times so the contacts themselves would buff the surfaces. I then sprayed both sides out with contact cleaner and put it back together.

I haven't had any more sensor tests fail on the GS 911, but I am getting a little frustrated with it. Everytime I hook it up it fails to read on the autoscan until I go to the K series tab and manually do a brake code read. After that I can do the autoscan. Seems like after a few reads the tester will disconnect and I have to unhook the 911 and reboot it to do any further reading. I had cleaned the contacts of the diagnostic port to make sure they were good.

The bleed test can be performed at any time. You really have to work at it as you squeeze the lever to keep the display in the green , centered in the marks. I usually have to use two hands for the front test and lots of foot pressure for the rear. If it passes you have no air in the system.
@jzeiler, is this the brake bleed test you are referring to?

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I haven't been able to get any readings during this test, but after rereading your post, I think I am not squeezing the brakes hard enough during the test.
 

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That looks a bit different from what I see when I do it. I get a elongated box with a smaller inset box (target) and when I squeeze the lever there is a red bar that goes across the the long box and when the end gets to the "target" box it turns green and I have to hold it in that smaller box to get a good reading. Looks like you are using wi-fi on a phone, mine is hooked USB to the computer so the SW may be different.
 

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I know this has been discussed a lot on the forum and I have read a crap ton of the threads posted here but none of them seemed to be exactly what my symptoms presented as so I decided I would add mine to the ever growing list of ABS posts.


I am not sure if these symptoms indicate a failing ABS control unit or not, but I am getting to the point of frustration. I am quite confident it is an electrical problem since every time I have gotten the warning lights I was not actually using the brakes, only rolling.

Any help or guidance would be appreciated.
I own a different bike, an RT, but I think the ABS sensor may be the same. In any case, I have worked out a procedure to test the sensor and the wire in the field, and I made a video about it. Possibly this will help you:

 

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Discussion Starter · #24 ·
I own a different bike, an RT, but I think the ABS sensor may be the same. In any case, I have worked out a procedure to test the sensor and the wire in the field, and I made a video about it. Possibly this will help you:

I actually have already watched your video. I found it what searching for info on the problem.

I enjoyed the video and it had a lot of good info. Thanks for posting it.
 

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That is normal as the fluid really does not go anywhere since the input is fully isolated from the servo output.



You cannot use just the back brakes (except for very light trail braking) as they are fully linked and you will get both front and rear regardless of the input.

This diagram shows the basic function of the system.

View attachment 171732
Great info and education, tnx for the diagram and explanation.
Gary
 

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Discussion Starter · #26 ·
After putting the bike back together and clearing all fault codes I took it for a test ride and the fault lights immediately came on after the self test. The brakes were bled and the connector to the ABS unit was removed and cleaned with contact cleaner.

I checked it with the GS911 said the fault code was: 16769 Internal control module error-Slip duration was too long during regulation

The error codes of the sensors did not show up this time, just the internal control module failure. I am afraid this means my control unit is bad and needs replacing. Module Masters currently has the LT module fixing frozen until after January 2021.

I have a second ABS unit on a parts bike but I am skeptical about it being worth swapping over. That bike has 100k+ miles on it and has sat for a while. I don't know if it is worth the effort of taking it off of the parts bike and putting it on my bike and bleeding the lines just to see if it gives any error codes. I guess I should give it a go and try it. At the worst case scenario it fails and I just loose brake fluid and time and labor in the attempt.

I am also looking at the ABS removal but I am not sure how that would be done. Can anyone post a link to a thread explaining it all in detail?

Getting frustrated at this point....
 

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You can swap just the electronics part with that of your spare unit pretty easily, without affecting the hydraulics. The only problem is access... you may need to take the whole unit out to swap the electronics. I think you should do this. The hydraulics on the old unit might be compromised from sitting, but the electronics won't.

When you remove the fasteners on the end cap where the big ABS connector goes, you have connections from the circuit board to the motors, solenoids, and pressure sensors. Just reconnect them exactly the same way. Two of them (the sensors and I think the motors) have keyed connections but the third one can be reversed and you will get an error.
 

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Here are some shots of what you will see. The last one is to help you find the servo (red) and pump (yellow) connectors in picture 2 as you can't see them very well in this shot. Since yours is a pre facelift access to this area is very easy.

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Discussion Starter · #29 ·
You can swap just the electronics part with that of your spare unit pretty easily, without affecting the hydraulics. The only problem is access... you may need to take the whole unit out to swap the electronics. I think you should do this. The hydraulics on the old unit might be compromised from sitting, but the electronics won't.

When you remove the fasteners on the end cap where the big ABS connector goes, you have connections from the circuit board to the motors, solenoids, and pressure sensors. Just reconnect them exactly the same way. Two of them (the sensors and I think the motors) have keyed connections but the third one can be reversed and you will get an error.
I think you may be on to something here @AntonLargiader. I broke the seal of the two halves tonight and had a look around. There was corrosion inside on some of the screw heads and there was extra silicone around the seal. Apparently someone has had the two halves apart and tried sealing it back up with silicone.

There is no telling why they had it off but the corrosion doesn't look good. Hopefully swapping out the electronic boxes will fix my issue.

You were right about not having room to work, it is very cramped right there. Hopefully I can get it out and replaced tomorrow.

Thanks for the tip.
 

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There is a lot more room on the pre 05 than the post 05.

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Discussion Starter · #31 ·
I got the electronic portion off the top of my ABS control unit and the donor off the parts bike. They look identical to my untrained eye, the connectors appear the same and the diodes, resistors and circuit boards look the same inside as well, but I compared the numbers and they don't match. I am wondering if this matters?
My bike is a 2002 ad the donor bike is a 2003. I am not sure if the ABS units have been changed before I owned either one of the bikes.

My question is are these electronics interchangeable?

My bikes electronics -

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The donor bikes electronics

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Any insight into this would be appreaciated.
 

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They should be OK, 2001 - 2004 were all pretty much the same parts. All the external stuff (to the ABS module).
 

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Looks like an updated version to me. Should be an advantage to use it. Hardware change from revision 8 to 10 and software from revision 5 to revision 7.
 

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Discussion Starter · #35 ·
Ok, I will swap out the electronics tonight and give her a test run.

Help me understand the options I have if this doesn't fix my ABS.

1. Pay out the wazoo for a new ABS unit ( not happening ).

2. Pay a little less out the wazoo for a rebuilt ABS unit ( seems they are out of service for the immediate future, not really an option )

3. Ride on residual brakes-Pull the lights on the instrument cluster and let the ABS remain in a failed state and operate on the residual braking. Leave everything hooked up like it came from the factory on all the brake parts (except the warning lights of course).

4. Not sure If I understood this option correctly, I can pull the ABS relay under the gas tank and continue to use the brake servos for power assist, I just wont have the ABS portion of the brake system.

5. Old school brakes-If I remove the ABS unit and connect the master cylinders directly to the calipers I will have the old school brakes, no servo assists, no ABS and the brakes will no longer be linked. The power applied to the brake calipers will just be what is generated from my hand or foot, old school. I know that I need to remove the ABS relay and light on the instrument cluster and I also know that I need to keep the electronic circuit board from the ABS unit connected ( minus the servo leads ) to be able to have the cruise, speedometer and brake lights. Anything else that I may have missed for old school brakes?

Please let me know If I am on target with these options. It is a little confusing scouring through 100's of threads and opinions on what the options are.

Thanks so much in advance.
 

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On #5 just need to cut two wires at the plug to kill the warning lights. No need to pull the ABS out either as you just tie the front input to the output with a couple up on the fork area and get a custom made hose to go from the rear MC to the caliper.
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Old school braking is just fine as that is what the 99-2001 had anyway with no servo no linked. That is the most popular option for full failure of the servos system.

On #4 if you have failure of the system servo use is not recommended since it will be too easy to lock them up.

On #3 Residual braking is not good enough to ride the streets with.
 

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I replaced the abs control unit on my 09 LT and cant find the amount of fluid to add to the unit initially, anybody know the amount?
 

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Just fill it to the level shown here. Then as you push fluid out to the calipers check the level. The front wheel circuit reservoir (tall) holds about twice as much as the rear wheel circuit reservoir. I have filled systems after a full brake line set install and did not use more than two pints of fluid. Of course you will have to fill and bleed the control circuits first before you can do the wheel circuits. Those are done with the key off.

If all you did was pull the unit and replace it with no lines changed out you can get by with only a pint. When I suck out the old fluid for a flush I get about 45 ml out of the front and 30 ml out of the rear.

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thanks John, what a mess!
 
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