ABS2 flashing light, fault 7, NOT the battery

[khpossum]

2002 1150GS, ABS2 brakes, 35k miles, I have had it for a year. ABS fault 7

Here is the history:

I changed rear brake pads a couple of weeks ago, no problems, everything OK.

Bled front and rear brakes 2 weeks ago (DOT 4 fluid, last time was a year ago). The fluid coming out was slightly caramel colored and no bubbles. Bled at the calipers until fluid was clear. Everything great!! Never touched the sensors or sensor cables.

When I drove off the dreaded ABS 1 Hz alternate flash came on with the normal ABS clang / kebang after 20’. I checked the error code on the diagnostic plug and it shows 7 blips on my old analog meter indicating fault 7, or ABS module. I reset the ABS (8 second ground on pin 2) and lights go back to normal. Key off – key on – start - lights OK, simultaneous blink. I drive off and as soon as it does whatever it is doing after 20 feet the fault comes back. Checked again, same error code. I did a reset again, same thing happens.

I re-bled the brakes. This time also bled the two ABS bleeders under the tank for a long time, trying to clean out the control unit. Clean fluid came out of it as well.

Reset ABS and same error comes back after driving the initial 20 feet.

I know 100% it is not the battery, no need to bring it up (I think). Before someone suggests it, the brake levers do not touch the hand guard. Foot brake OK as well it appears.

Questions:
Now what? I love my ABS and want to keep it. This only happened right after I bled the brakes. Coincidence?

Is there any way to segregate a rear from a front brake fault?

Does the dealer ABS diagnostic say anything more then what my own diagnostic fault code shows?

New ABS controller? I have a hard time with this, too much of a coincidence that it happened right after my brake bleeding. Then again, I guess I could have bled something nasty into the ABS unit??

What else can I do? Is anybody rebuilding these ABS controllers? Has anyone taken thse things apart with any success?

Karst

 

[MattW]

Occam's razor (the simplest explanation is usually correct) says it's connected with your bleeding operation - a big coincidence that it should happen right after you did it.

Others will no doubt chip in, but while you say you didn't touch the sensors are you sure you didn't disturb the cabling or knock them when you were at the callipers?

best
Matt

 

[khpossum]

No, I did not touch the cables and a sensor fault would show as fault 3 or 4. Actually for a short time I suspected my new HID cabling might have something to do with it, but I had my first ABS incidence a couple of days before the first HID light up. The HID cables are not anywhere near to the ABS cables.

By the way to all of those who have had ABS flashing light, finding the fault code is really easy by checking the voltage on pin 2 on the diagnostic plug, takes 30 seconds and you can narrow down your options considerably. All it takes is a $4 Radio Shack analog cheapo analog volt meter or 12 V LED. I will find the article describing it and post the URL as soon as I find it again.

KP

 

[khpossum]

ABS fault determination and reset

Actually found a copy laying around on my desk:

http://www.largiader.com/abs/absfault.html

 

[CHANGELING]

Last winter my ABS went up the creek and after testing it I found the error code for the main unit failure. Refusing to believe it was fatal, 3 months later I went to the stealers for a reset to see what they would find and they recoded the ABS unit with my frame number or somesuch for a tidy sum of 30 mins labour rate and it cured it all. Of course highly unlikely in your case but as a second opinion before spending big dollars..........

 

[khpossum]

The plot thickens as they say. I removed my load shedding relay yesterday afternoon late, so my head lights would stay of. I installed new HID lights and wanted to make sure they were not involved in this ordeal. I had an ABS error prior to the installation of the HID's, but just wanted to make sure. Guess what, it seems the error stays away, even if I push in the load shedding relay in after the bike and ABS are all up and running. I need to do some more checking to make sure this is not a false trail.

We have 8 cm snow last night, so not much riding today, unless the snow melts later today.

Karst

 

[Pat]

ABS fault 7

So did the fault ever come back?

I too am getting fault code 7. Does anybody know exactly what this means and what needs to be done/replaced to rectify the fault???
I know that fault 7 is "ABS control unit" so does this mean replacing the whole unit ? or is it possible to remove the unit and get it overhauled somewhere?
As they are very expensive I would only go down this route (replacement) if I knew that would fix it.
I have done the reset procedure (ground pin 2 etc..) many times, and the same fault comes back again and again......

Any info would be greatly appreciated.

2000 1150gs ABSII

 

[khpossum]

In the end I solved the problem by interlocking my lights with an alternator lead and an interposing relay (proving it was some voltage issue). My lights do not come on until the engine is running. It took care of all ABS low voltage issues. Even in the middle of Colorado wintertime my engine starts with no ABS errorrs, ever. Let me know if you are interested and I will dig up the information. The basics came from an article on ADVrider wisdom section and then I changed it slightly to make it a bit easier to install. http://advwisdom.hogranch.com/Wisdom/ABS_Low_Voltage_Fix.htm

The odds you need a new unit are pretty slim, it seems it is almost always a low voltage issue.

Advrider also had some correspondence about people who have taken their unit apart, trying to fix it, with some limited succes. What I got out of their story is that it may help if you excercise your ABS once in a while. It seems that may avoide some of the other ABS unit problems (when it not just by far the most common low voltage thing). http://advwisdom.hogranch.com/Wisdom/BMW%20ABS%20II%20D&A.pdf

KP

 

[Pat]

In the end I solved the problem by interlocking my lights with an alternator lead and an interposing relay (proving it was some voltage issue). My lights do not come on until the engine is running. It took care of all ABS low voltage issues. Even in the middle of Colorado wintertime my engine starts with no ABS errorrs, ever. Let me know if you are interested and I will dig up the information. The basics came from an article on ADVrider wisdom section and then I changed it slightly to make it a bit easier to install. http://advwisdom.hogranch.com/Wisdom/ABS_Low_Voltage_Fix.htm

The odds you need a new unit are pretty slim, it seems it is almost always a low voltage issue.

Advrider also had some correspondence about people who have taken their unit apart, trying to fix it, with some limited succes. What I got out of their story is that it may help if you excercise your ABS once in a while. It seems that may avoide some of the other ABS unit problems (when it not just by far the most common low voltage thing). http://advwisdom.hogranch.com/Wisdom/BMW%20ABS%20II%20D&A.pdf

KP

Hi Khpossum,

Thanks for the fast reply, that is very good info you have for me. I would be very interested in trying out the method you have successfully completed on your bike.
I too have installed HIDs recently,on both dip and main, around the same time as the fault arose.......
I understand fault 5 is for the low voltage at the ABS control unit, but I am getting fault 7 all the time. Would I be correct in saying you were having the same problem as me, and you have proved that it is also a low voltage issue?

Many thanks for your help.

Pat.

 

[khpossum]

Yes, it without any doubt was error 7 I got. I believe it was some low voltage or voltage spiking issue, since I fixed it by means of what I described. Having said that, there are also plenty of reports of HID causing problems when its wiring runs too close to certain BMW wiring. Plenty or reports of weird things going on with the display. So, make sure your HID wiring is not running close to your standard wiring.

Regardless, prior to installing the HID wiring I had also frequent cold weather low battery voltage issues when starting a cold bike. That could only be resolved by riding for a while, stoppping and restarting. Not hard, just a PITA. That is however an event that does not require a hard reset, just a restart. That issue also completely went away if the head lights don't come on prior to the engine running.

Not sure why, but it solved my problems.

Really close to and inspired by the link I send you earlier. http://www.advrider.com/forums/showthread.php?t=443299

KP

 

[khpossum]

more the you ever wanted to know about fixing an ABS 2. Makes interesting reading.

http://www.advrider.com/forums/showthread.php?t=457863