1992 K75S ABS light constantly on

[broadstone]

In another discussion I broght up the multitude of problems with an "as is" not running K75 that sat unused for at least 2 years. With the help of several members I now have it running pretty well but with some remaining issues. The ABS light is on as soon as the ignition key is turned on but remains on solid no matter what else is done such as setting with the brake while riding or toggling the ABS switch. Many of the problems I've had we're electrical related so I suspect it may be related to that. Also, I believe that the left front caliper is frozen and am wondering if that could be related to the ABS indicator lamp staying on. The fuses are good and this is my third BMW with ABS so I'm familiar with the procedure for having this light turn off. I think I'd be more comfortable with the problem if the light was at least flashing. Any assistance would be appreciated.

 

[98lee]

Jim,

First thing I would try is to reset the ABS.

http://ibmwr.org/ktech/abs-reset2.shtml

Only comments I have about the above link is the connector or the plug in the connector will be light blue. Push the ABS switch for 60 seconds as opposed to 20 seconds. Exact time doesn't matter, but sometimes it takes longer than 20 seconds.

It might be the only problem, might not.

 

[broadstone]

K75 ABS probs

Thanks, Lee. I forgot to mention that the battery is reading 10.2 volts and much higher with the engine running and the brake light is working. I'll look into the reset solution as soon as I find clear instructions for doing this.

 

[HFbmw]

k75abs problem

Need a new battery, me thinks. That will start solving the abs problems.

 

[Zagando]

Exactly the same problem I encountered twice over the last four years---the culprit was low resting voltage---replace the battery* and reset the ABS using the ground wire trick and I bet you'll be good to go thereafter.

(Or if it's been sitting for a long time a good full recharging might suffice but make sure it can hold a decent charge. IIRC the resting voltage should be at least 12.4 volts but if I'm a bit off on that perhaps Lee or someone else can correct me).

It really helps to know the fault code and next you're near a Radio Shack pick up a 12 volt LED part # 276-011 (I know it by heart!) to use as your Official BMW ABS Fault Code Reader. $2.95 + tax; expensive but worth it!

 

[Zagando]

Recommendation if you need a new battery

PS: If you do need to replace the battery I can totally recommend an outfit called Euromoto Electrics up in Denver---after searching on the Internet a good while they had the best price with shipping overall---and their service and packing was exemplary. I went with the heftier Westco 30AH job and I suspect it'll serve me well, too.

 

[broadstone]

K75 ABS light always on

Thanks again, all. I forgot to mention that the battery is brand new and reading above 12V static. Anyway I tried the wire in the middle contact procedure using the link that Lee provided in the above post and it worked. At least the light is now flashing but I haven't yet ridden it to see if it will cancel with the brakes. I'll follow up when I get the tank back on the bike. Wow, Its starting to feel like I'll have a complete and running bike at some point. BTW, I would like to trade up or down for an R in similar condition so will place that ad when I'm satisfied that this is a good running reliable motorcycle.

 

[98lee]

. BTW, I would like to trade up or down for an R in similar condition so will place that ad when I'm satisfied that this is a good running reliable motorcycle.

ARE YOU CRAZY???????

You've just about got this one sorted out and haven't even learned what a sweet bike it is capable of being and you're already thinking of DOWNGRADING to a boxer?????

You disappoint me. You sounded smarter than that on the phone. I guess I need to get my phone checked out.

 

[argent brick]

ARE YOU CRAZY???????

You've just about got this one sorted out and haven't even learned what a sweet bike it is capable of being and you're already thinking of DOWNGRADING to a boxer?????

You disappoint me. You sounded smarter than that on the phone. I guess I need to get my phone checked out.

LOL

You just can't beat a brick. I dare you to show me another 20 year old fuel injected motorcycle that still has good dealer support. Dollar for dollar, you get more bike for the money when you go with a Flying Brick.

Brick and Boxer, I have owned both. They are completely different machines. I would not mind owning another boxer, but I question if I would part with my K bike to get one. The airhead would have to be perfect and the exact model I was looking for,
down to the bike's color and brand of tires. Even then it would be a hard choice.
The K bike is that good.

Give your Flying Brick one or two seasons on the road before you consider parting with it.

 

[Zagando]

Yeah, but, no, but...

Lynn and Lee are so right on this; I can't believe that you'd want to do that.

While I still cherish the memories of my old boxers that I rode all over the country in my younger days I do not miss their cantankerous and somewhat unreliable nature.

The really good thing about an airhead is that once you sort out or replace the brakes, most of the the electrical system, the carburators, the circlip issue (in some years), the shocks, the fork springs, the $2000 O-ring, etc., etc., you have a pretty nice bike that's fun to ride.

Of course, you're still ending up with bike relying on a pushrod-type powerplant that was basically designed in the 1920s.

 

[broadstone]

K75s ABS light

Wow again. This K75 is my third so I know what a nice ride it is; I've always claimed that it is, perhaps, the best bike that BMW has made for several reasons. This is the tenth BMW that I have owned over the last 50 years most of which were larger displacement K's and about half were new or nearly so, so, except for having rebuilt the transmission on an R75/5 my experience having to work on them is limited. I've done a lot of work on this particular basket case and, although I now have it on the road, there are still many concerns that I've identified and assume that new and expensive ones will continue to pop up. I'm retired but this thing could become my new career so I think I might want out. There are several reasons why I like the older R's; one of these is that I'm more familiar with the simpler technology of the older ones and, because of my age, I prefer a lower seating position. The history of my having decided to buy this particular bike involves, to some extent, helping a friend out of a tight financial spot. I wasn't even in the market for a motorcycle. The bottom line is that it is a little judgemental to question my taste in bikes. As a matter of fact, I've ordered a replacement seat which might be a bit lower in which case I may be more inclined to continue with this one.

 

[Zagando]

Fair enough, Broadstone; thanks for enlightening us---guess we did sort of jump to conclusions but your announcement shocked us Brickheads. I didn't mean to offend you at all.

I'm nearing retirement age so I really know what you mean about a lower seating position than on the Ks. But keep in mind that a low seat is available for the K75 models that might fit you perfectly. Barbacks also make your riding position customizeable, too.

Unless the K you bought to help out your friend has been really neglected I suspect that once you get the last couple things sorted you'll honestly be good to go mile after endless mile reliably and inexpensively.

I got around 31-36mpg on my carburated GSPD; 45mpg at best on my R75/5; now I get 44-51 on my injected K75S. With today's fuel costs that's a consideration.

Now that my valves have been adjusted the only other potential big job on the horizon is a spline lube. Since I'm not yet having trouble downshifting from 3rd to 2nd I figure that can wait a bit longer until I can afford to have a proper job done by my factory-trained mechanic. (Save my back and aging knees)

I do understand the love affair with R-series Beemers and if I really could afford to I'd have another for tooling around the twisty desert/mountain roads once in a while. But if my choice is between an R and a K for only one bike in my garage it would be an early K any day.

 

[broadstone]

1992K75 ABS issues

Thanks, Zagando. I appreciate your reply and understanding of my position. I should have realized that commenting in a way that it sounds like I prefer R's in a general sense over K's on a Brick forum might have been asking for what I got.

Anyway, to continue with my saga, I have gotten a great deal of good information from contributors like yourself but Am still amazed that one bike could have so many issues related, primarily, to poor maintenance and botched attempts at repairs. Right now I'm trying to sort out the ABS. When I started out, the ABS light was solid on with the ignition key on and stayed on while riding. I used the wiring schematic that I bought from Prospero's Garage (very nice publication) because so many of my many problems were related to broken and missing wiring. As far as I was able to determine, all wiring related to the ABS circuitry is intact. I reset the ABS and now the light flashes but won't cancel with the brakes while riding. The battery is new and checks out as having a very good charge and the brake light functions correctly.

Probably unrelated to the ABS, the front turn signals and horn don't work, and I'm still having trouble locating where a black wire with a round terminal coming from the right side of the instrument cluster is supposed to be attached. There is already a black wire with a round terminal attached to the throttle assembly which I assume carries the ground to that location but the schematic shows no black wires in that location.

I know that with help, I will eventually sort this out but at least I'm riding again mostly due to the contributors on this site. BTW, if the seat thing works out, I will definitely keep this bike, probably as my last. At least I have learned a great deal related to getting at and servicing much of its components. Spline lube is next.

 

[Zagando]

Don't know for sure but I might suspect there's still a faulty ground connection somewhere in your system. Imagine you've already checked the fuses, right?

Sometimes when resetting the ABS I've had to make several attempts to get it right. Btw, I had a low battery a few months ago so I replaced the battery.

Then I got the faulty switch (relay) fault code---so I replaced the relay (1 of 2) and that fixed it. But with your wiring harness a bit chewed up or faulty it's certainly not easy to diagnose.

Hopefully Lee will chime in ASAP and tell you exactly where that black wire goes---maybe that has a lot to do with your problems. Good luck, I'll check back later to see what others post (and I'm hoping for comments on my damaged radiator pix that I just posted in my K75S Chirping Noise When Hot thread here also).

Now I'm heading out to resume work on installing a new fan motor.

Btw, glad to hear that you might keep the K and we're all glad to help you here as much as we can.

 

[98lee]

Jim,


The battery voltage is way too low for the ABS to function properly. Are you checking the battery voltage at the battery terminals or at some other point (could be a bad battery or just bad corroded connections). Correct this FIRST. Could be dirty Ignition or kill switch contacts, depending on where you are measuring the voltage.

Next thing you need to check on the ABS is the sensor gap front and rear. Should be .014-.025". Check several spots around the sensor ring to make sure that it's running true.


Your rear turn indicators work now RIGHT??? (in a previous post you said it was the REARS that didn't work!!), so the problem with the fronts could be:

* indicates most probable

*bulbs

*sockets (check for voltage. If yes, check for ground [if ground bad, check main ground bundle on frame under tank. If no voltage, keep going down this list)

front turn signal harness

*connector between front turn signal harness and main harness (behind headlight area, might be unplugged)

Main harness to flasher relay (unlikely unless it got cut like your other harnesses, then bingo!)

Flasher relay (also unlikely but the last possibility if everything else checks out)


Horn:

Bottom fuse (also feeds ALL the turn indicators)

Bad horn (or not enough current getting through corroded connections to run it)

Horn relay

Horn switch

More cut wires in your harness


All this stuff is pretty easy and cheap to fix IF you are methodical in your troubleshooting. None of this is normal stuff. Your bike has been abused. Corrosion has been accelerated by it being kept under a tarp. Wires have been cut. Once this bike is right, there is very little reason for these things not to stay right.

 

[98lee]

The battery is new and checks out as having a very good charge

Checks out how? 10.4 volts is NOT even 10% charged.

I'm still having trouble locating where a black wire with a round terminal coming from the right side of the instrument cluster is supposed to be attached. There is already a black wire with a round terminal attached to the throttle assembly which I assume carries the ground

Could it be the other end of the wire going to the throttle assembly?

A picture would be helpful.

 

[broadstone]

K75S ABS light

Lee, I rechecked the brand new battery and charging strength and found the static battery voltage to be at 12.3V and 13.8V at the battery with the engine at fast idle. One thing I forgot to emphasize in previous posts is that the headlight, parking light, speedometer, tachometer, gear indicator and high beam indicators all work.

* I mis-stated the voltage; I should have said 12.4 not 10.4

*the counter gear to ABS sensor distances are within specs

* Front turn indicator bulbs are good and there is no voltage going to these sockets

* All harness connections to the front end appear to be plugged in

* Flasher relay and harness seem to be OK because rear turn signals flash but flash fairly rapidly.

* As far as the horn goes, I've had horn problems with 2 other BMW's, both of which were related to bad grounds. I'll get to that later.

Lee, this bike has so many issues that it almost appears to have been sabotaged but the more effort I put into it the more my feeling of ownership grows. My new seat arrives today and I have all but abandoned any thought of parting with this resurrected machine. Now, if I could only find some pearl white touch up paint. Thanks once again. Jim

 

[98lee]

Check for voltage at the front turn signal harness to main harness connector (in the headlight area). If none, it's either a cut in the main harness to the flasher or a bad flasher (flasher relay has separate output connectors for front and rear).

Take a jumper to the horn with 12v to test the horn.

Don't give up, you're getting close.

Is the seat you ordered a factory low seat?

 

[broadstone]

K75 abs

I thought I should update my last post. On the issue of the non-working front directional signals, I found that there were bad ground connections at both light terminals. They now work. Also, all the instrument lights are working including those associated with light testing and ABS function. The only indicator questionable at this point is the low fuel light which stays on, but I only have about 1/3 or less fuel in the tank so that may not really be a problem. I'm close so as soon as I lubricate the driveshaft splines I'll feel safe riding it but I'll contnue trying to solve the ABS problem. It runs and rides great now with only a hint of valve noise. Thanks again. I'll stay with it to the end.

 

[Zagando]

Jim; The low fuel light coming on with a 1/3 tankful is normal. I ride around on reserve for days, go to a gas station (Chevron has Techron which is good for all Ks) and it'll take maybe only 3.5 gallons or so to fill her up.

I understand that if this early warning bothers you there is a way the long float arm that is part of the fuel sending unit inside the tank can be bent (downwards, IIRC) so that it will come on later. Then it'll better reflect a reserve amount.

Glad to hear that you're getting close and try to post some pix when you can. That pearlescent white is a nice color, isn't it?