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Thread: ABS1 fault - Hail Mary play '92 K75S

  1. #1
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    ABS1 fault - Hail Mary play '92 K75S

    My ABS fault has cleared. Last fall my 92 K75S (77K miles) threw an ABS fault while tooling along the highway. I taped over it and kept going. Next day I was near Heid's in the Daks so I stopped to see what the fault code was. Rear modulator. "Want us to change it out?" $$$$$$$$$$$$$$ "No thanks, I'll just ride it home."

    Since I do my own wrenching I took the time to eliminate other possibilities first. Even used ABS1 modulators were expensive and gave no assurance that they would last even a day. Big gamble and NOS modulators just take my breath away. So, over the winter I've been going thru the bike working on connectors and connections hoping for a Hail Mary repair before I dropped the big bucks and opened the brake system.

    I cleaned/worked the ABS brain connector, the relays, all the blue plugs and any other connectors I could find. Even if it was not ABS related it had been a long time since original assembly. Inch by inch. Last Friday I removed the right 'battery cover' and cleaned the 5 connectors there. CRC electrical or electronics cleaner seems to work nicely but it really helps to use a pipe cleaner as well (remember pipe cleaners????). Wet the pipe cleaner with the CRC stuff and GENTLY swap out the sockets and wipe down the pins. Look at the munge on the end of the pipe cleaner. Did a long ABS reset (75 seconds just for good measure - thanks Don) and buttoned all that back up.

    Started the bike and, for the first time in 6 months, got normal ABS lamps. Tested both brakes and got normal lamps. Rolled down the driveway and the lamps cleared. Woooooo. Hail Mary worked again. Rode 60 miles over back roads and potholes and got no new faults.

    An owner/mechanic will take the time to work thru the bike before throwing big bucks at a problem. The BMW Certified Technician will normally not have the time so will just start replacing parts. That could have cost me a fortune.

  2. #2
    Dum vivimus vivamus ted's Avatar
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    Excellent, insightful write-up - thanks!

    Did you use dielectric grease at all after the CRC/Pipe Cleaner trick?
    Ted
    "A good stick is a good reason"
    1994 K75RT
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    No I did not use dialectric grease. You'll recall that dialectric grease, though is can help reduce corrosion by keeping moisture away from the metal, is an insulator vs an electrical conductor. I decided the basic design of the connectors and the relay box and the tail section keeps the components pretty dry already. Since some of this stuff is pretty low voltage and low current use I did not want to introduce an insulator. And them connections went almost 20 years before problems appeared. Now, do I wait another 20 years before checking this stuff again? Nope, I've learned my lesson. Good task for the winter work list.

    Besides them'ns some tiny pins and sockets and I donno how to wiggle a thin film of dialectric down in there. My thumbs are too big.

  4. #4
    Mudbug
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    Every once in a while, my ABS shows a fault, rear modulator. I made a kit that includes the instructions stored and a freezer bag. I open it up, follow the instructions and the ABS fault goes away.

    The dealer wanted to make a "big deal" about it. No thanks. My guess is there is a connection somewhere that needs cleaning.

  5. #5
    BMW uber alles! Zagando's Avatar
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    Thumbs up

    Quote Originally Posted by tpbyrum View Post
    An owner/mechanic will take the time to work thru the bike before throwing big bucks at a problem. The BMW Certified Technician will normally not have the time so will just start replacing parts. That could have cost me a fortune.
    Excellent point worth repeating. Your commendable perseverance really paid off!
    ---Jeff

    ex: K75S Berlina R100GS/PD , K100RS , R75/5 , R60/2

  6. #6
    A bozo on the bus deilenberger's Avatar
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    Quote Originally Posted by tpbyrum View Post
    No I did not use dialectric grease. You'll recall that dialectric grease, though is can help reduce corrosion by keeping moisture away from the metal, is an insulator vs an electrical conductor. I decided the basic design of the connectors and the relay box and the tail section keeps the components pretty dry already. Since some of this stuff is pretty low voltage and low current use I did not want to introduce an insulator. And them connections went almost 20 years before problems appeared. Now, do I wait another 20 years before checking this stuff again? Nope, I've learned my lesson. Good task for the winter work list.

    Besides them'ns some tiny pins and sockets and I donno how to wiggle a thin film of dialectric down in there. My thumbs are too big.
    BIG +1 on not using "dielectric" grease on these contacts. BMW calls for Stablant22 - which costs about what some expensive designer drugs cost, but luckily, you only have to barely dampen a connector for it to work it's magic. It is available from NAPA autoparts dealers (PN CE-1, for Contact Enhancer-1) - if you look forlorn when they tell you the price, sometimes they'll give'ya a deal. Good stuff.
    Don Eilenberger http://www.eilenberger.net
    Spring Lk Heights NJ NJ Shore BMW Riders New Sweden BMW Riders
    '07 R1200R (current ride) and some bimmers.. and a Porsche

  7. #7
    Registered User MCRyder's Avatar
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    Congrats on getting the ABS back online.

    Wish I'd known about cleaning those 5 connectors 4 years ago. My '93 K1100RS did the same thing, ABS light began flashing as I rode down the highway. A DIY diganostic said the same thing, rear modulator. I got a quote of $1,900 for a NOS replacement. I did all the cleaning up of connectors, except the five you did. Never did get mine back online, just rode it as it. Sold it January of last year, woulda gotten more $ if the ABS had been working.

    Sometimes it's all in the details.
    Mark Rooney
    Lindale, TX
    2012 Aprilia Shiver 750, 2008 Suzuki Bandit 1250SA
    ( '93 K75, '94 K75, '93 R100RT, '93 K1100RS, ? )

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    Kbiker BCKRider's Avatar
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    My congratulations to the OP for solving the problem and my condolences to the last poster (and a person with far more mechanical abilities than I) for not - and losing major bucks when he sold the bike. Hope the buyer of the bike reads this post.

    My bike also has ABS-1 and so far no problems. It ticks me off that, apparently, BMW dealerships do not have on their computers the simple things to check for common problems on older bikes before they try to to sell you that very expensive part - which likely must be ordered.

    Even though I have learned from experience that, for me, DIY is a bad idea when it comes to dealing with motorcycle problems or even maintenance, the wisdom from this forum has saved me a lot of bucks. I can tell that qualified motorcycle mechanic what I want him to check and often in what order.

    You guys provide a great service for not only the "wrenches" but also for the "mechanically challenged."

    Thank you!
    Doug
    1992 K100RS

  9. #9
    Kbiker BCKRider's Avatar
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    Why did I say that!

    I was the last poster on this thread and on April 2 wrote "My bike also has ABS-1 and so far no problems." How can that bike read my posts when I don't even let her into the house? And why is she so pissed?

    Today, about 15 miles from home, the "brake check" and ABS lights started flashing. So I'm hoping that I'm about to learn about some reasonably easy electrical cleaning rather than some very expensive part replacement.

    If it helps, the battery was charged and the bike started instantly at the beginning of the ride and the two brake lights behaved normally - flashing ABS light going off after rolling a few feet and the other brake light going off after I touched both front and rear brake levers. Never seen this fault before. Pressing the "ABS switch" caused both lights to stay on solid. (What is that switch for anyway?) I pulled over and shut off the bike. On re-start, was back to both lights flashing.

    Is there an easy way I can reach the connectors, which were the problem for the OP, on my 92 K100RS?

    Fault codes, etc. are Greek to me. Can you direct me to other info (I gather there is quite a bit) of what to have checked rather than re-write it all? Search...? I'm almost at bad at finding stuff on this forum as fixing my own bike.

    Your patience as well knowledge is most greatly appreciated. Thanks.
    Doug
    1992 K100RS

  10. #10
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    Doug, I'm glad my original posting inspired you. Your problem sounds as electrical as mine was. Good luck.

    Start with the ABS articles on the IBMWR tech pages. The info Brian Curry et al posted is valuable. If I had been home when Prowler threw his ABS fault I would have used an LED (explained in the articles) to read out the fault myself. When Prowler faulted I was 400 miles from home so I stopped at a shop (I'd meant to go see Heids anyway).

    The ABS reset switch on the dash is just to stop the flashing for a little while. It starts up again (maybe 10 minutes later) to remind you you have no ABS and you need to hit the switch again. i did this for about 100 miles then got out some black tape and covered over the lights. They made me crazy. When I got home it did help to know what the code said (rear modulator in my case) cuz I generally focused on that end of the bike. The fault code can tell you where to start so you don't just shot-gun things.

    The last set of connectors I worked on, as mentioned, were behind the right side panel, under your right leg. Some would call that the battery cover panel. Once removed you'll see 5 or six connectors tucked away. One is for the stuff in the fuel tank and is not ABS related but you'll need to open that one anyway if you remove the tank to get at more ABS connections and relays. The other connectors may be related but it ALL depends on what fault code you get. I cannot advise from here in the dark. The ABS reset procedure on IBMWR and that Don has mentioned here works nicely. I keep a hard copy with the owners manual in my tail section (well, actually, Prowler's tail section).

    As Don and Brian and others have said all these years: electrical trouble shooting requires a methodical approach and a basic understand of the circuits you're working on. Yeah there are Hail Mary plays but no magic pills. I also searched this forum for ideas and you could search the beeg list too, I suppose. Go read out the code and start from there.

  11. #11
    Registered User MCRyder's Avatar
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    Anton Largiader also has an excellent write-up on ABS. I used his methods when looking for the fault code on my K11RS. And the LED method of reading the fault is very reliable. I went to the extra expense of having the the ABS checked for faults at a BMW dealer. Same result, left rear modulator. $105 for them to check it, $2.95 for the LED. Here's the link:

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

    I'm almost willing to wager that BCKRIDER will get a rear modulator fault code. That seems to be the most common fault with the scenario of being on the bike riding with a good battery.

    Again, kudos to you, tpbyrum, for posting your experiences on cleaning the connectors and getting the ABS system back online. This might turn out to be a huge boon to those ABS 1 owners who have experienced the dreaded flashing ABS lights.
    Mark Rooney
    Lindale, TX
    2012 Aprilia Shiver 750, 2008 Suzuki Bandit 1250SA
    ( '93 K75, '94 K75, '93 R100RT, '93 K1100RS, ? )

  12. #12
    Dum vivimus vivamus ted's Avatar
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    I just stopped at Radio Shack the other day to pick up a 12v LED and a length of 16g wire, along with a couple alligator clips - figured I would make a code test and reset package to hide back in the cowl. This is what I got, haven't tested it yet to see if it will work (was $2.59.)


    back:
    Ted
    "A good stick is a good reason"
    1994 K75RT
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  13. #13
    2-up and havin' fun sugarhillctd's Avatar
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    Nice diagnose/repair kit there, Ted.

    My now departed K1100RS had an ABS I mind of its own. It could go months without having a fault- then have 1, 2 or 3 within a few days. Had the #2 pin to ground reset down to way under a minute.

    Perhaps the OP's connector clean up would have done the permanent fix. Don't know- now it is someone else's concern.

    Gas and go is all that's needed on my new "K" bike.......
    John & Cathy
    '92 K100RS (gone- '04 R1100S Boxer Cup)
    '12 Suzuki DRZ400
    ("kid's" bikes) '02 Kaw ZX6R- Jen's '07 Duc 800ss- Johnnie's

  14. #14
    Kbiker BCKRider's Avatar
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    still confounded

    My mechanic (no DIY, I) still can't figure out why the ABS on my 1992 KRS stopped working or what to do to fix it. I'm hoping that one of you can suggest what to try next after reading all the boring details.

    1. Several weeks ago he found (with a multimeter) a fault code 4 - rear wheel speed sensor. Not sure what he did, but after resetting the fault code no flashing lights for maybe 3 miles, then back on.

    2. Today he found a fault code 7 - ABS Control Unit. He did all the things suggested by the OP (contact cleaner, pipe stem cleaner, plus compressed air) on all those connections behind the right battery cover. He also used contact cleaner and compressed air on the big gizmo which plugs into the Control Unit. I rode maybe 8 miles, including one ignition off stop, with no flashing lights. Then they were back on. Continued home to pick up my Clymer's - which is very sketchy about ABS. Then back to the shop.

    3. Again, the mechanic got a fault code 7. Upon reset, I looked at the odo as I rode away. It only took 3 miles before the lights were flashing again.

    4. I've since revisited the IBMWR and printed off Brian Curry's 1998 "ABS-1 Diagnostic Methods." Maybe that will give my mechanic a definitive check list.

    Questions:
    1. Ted, is that gizmo you got from Radio Shack able to do the diagnostic test without any other resistors and wiring and soldering? Can you also use it to reset the fault? A little more info would be appreciated.
    2. Anyone know if the fact that the ABS works for a few miles after a reset is indicative that the Control Unit is, or is not, the problem?

    Thanks in advance for your thoughts.
    Doug
    1992 K100RS

  15. #15
    Dum vivimus vivamus ted's Avatar
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    Howdy Doug,

    It is still in the bag so and I have not tested it yet. It cannot do resets, for that all you need is a length of wire, though preferably with an alligator clip or somesuch for a reliable ground.

    I will say I have heard on one persistent code 4 instance that turned out to be an intermittant fault in the sensor wire bundle at one of the zip-tie locations. Zip-ties are often on way too tight and wreak havoc with the inside wiring over the years. Have you measured the rear gap?
    Ted
    "A good stick is a good reason"
    1994 K75RT
    Moto Pages

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