95 k75 abs

[heejrbmw]

A while back I inquired about ABS on a 95 K75 that a friend was thinking of buying. They could not get together on the price, so it became a moot point. Now, they agreed on a price and my fried bought it yesterday.

In reading the service record, my friend sees in the paperwork where the BMW dealer disconnected the ABS computer and the light this past October. We are going to try to troubleshoot the ABS, but I'm unsure where they would have disconnected the light. Would anyone be able to help with that question? Is the disconnect in the relay box?

Thanks,
Ed

 

[dieselyoda]

This might a good place to start: http://www.k11og.org/forum/viewtopic.php?t=2110

 

[98lee]

Just guessing, but I would think the signal to the light is generated by the ABS computer, so unpluging the computer would also unplug the signal to the light.

 

[rdalland]

FWIW

My dealer unplugged the ABS brain on my '95 K75RT. The ABS dash light continued to blink.

The dealer disconnected it because it was unsafe to leave it connected. It stopped the rear brake from functioning at all - I had no rear brake due to faulty ABS computer. If your ABS light is blinking and your ABS computer is still connected, I would disconnect it.

I found a used ABS computer for sale and it has functioned correctly for a few years/couple thousand miles.

 

[heejrbmw]

Thanks for the information from each of you. With the differing thoughts, I just disconnected the ABS computer on my 92 K75S with ABS, and the ABS light went from flashing with the ignition switch turned "on" to a steady, non-flashing light. I haven't gotten a chance to try anything on my friend's bike yet.

ed

 

[heejrbmw]

Can anyone tell me if their ABS equipped K75 has 3 or 4 ABS relays plugged into the two relay bases? Am I right in thinking the two bases in the bottom right corner of photo are the ABS relays?

 

[rdalland]

I just disconnected the ABS computer on my 92 K75S with ABS, and the ABS light went from flashing with the ignition switch turned "on" to a steady, non-flashing light.

Reading this jogged my memory, my light stayed on as well - it did not continue to blink as I had previously posted. I blame CRS syndrome...

My ABS controller went out in 2006. http://forums.bmwmoa.org/showthread...ntrol-unit-failure&highlight=abs catastrophic

 

[98lee]

Ed,

You really need to get yourself a manual before trying to mess with the ABS.

The three black mini relays have nothing to do with the ABS.

The one that is missing is the ABS warning light relay. It should be a blue mini relay. There is no way the ABS light is on with the relay removed (unless the base is shorted, extremely unlikely), as the relay is the only source of power to the light.

Are you SURE it is the ABS light that is on? Left of the low fuel light on the speedometer face with the letters ABS on it? Or is it the bulb failure light with the triangle in the center of the dash?

The large blue relay is the ABS system relay.

First thing to do when trying to get the ABS functioning would be to replace the relay, check the front and rear sensor gaps, and reset the ABS system. Ride the bike and see if it faults again then read the fault codes and go from there.

 

[heejrbmw]

Ed,

The three black mini relays have nothing to do with the ABS.

The one that is missing is the ABS warning light relay. It should be a blue mini relay. There is no way the ABS light is on with the relay removed (unless the base is shorted, extremely unlikely), as the relay is the only source of power to the light.

Are you SURE it is the ABS light that is on? Left of the low fuel light on the speedometer face with the letters ABS on it? Or is it the bulb failure light with the triangle in the center of the dash?

Thanks Lee. I'm afraid I have not given enough information and thus, made it more difficult than it should be. I have confused everyone with my posts I guess.

Yes, I'm sure about the proper bulb. It will not illuminate currently. Nothing I can do will make it come on before the troubleshooting. That was my original post where I said the dealer had disconnected the ABS and disabled or disconnected the light.

When you responded to the original post with the following quote, I disconnected a computer in a different K75 to see if the light would go out and stay out. So, the post where I said the light was on was from a different K75 where I disconnected a known good ABS Computer, and that did not disable the light.

98lee
"Just guessing, but I would think the signal to the light is generated by the ABS computer, so unpluging the computer would also unplug the signal to the light."

The photo is taken of the K75 with non-functional ABS, that according to the PO, the dealer took two measures to disconnect the ABS computer; 1. disconnected the computer, and 2. disabled the ABS warning light. I have already verified the gaps and RESET the ABS. I have also swapped out a known good ABS computer in the K75. However, I still could not get the ABS warning light to come on. So, I was still looking for the reason the ABS light would not come on, since the known good computer did not make the light illuminate. Originally, I thought I was simply looking for a disconnected electrical connector somewhere in the main wiring harness leading to the speedometer. Thus, I got out the wiring diagram and started tracing wires. I saw the light circuit went through a relay which appeared to be located in the relay block where there appears to be a missing relay, as inquired about with the post with the photo. I concluded, that there is a missing relay, and that must be how the dealer disabled the light. I knew the light bulb was not burned out because I found a way to complete the light circuit without the relay, and got the bulb to illuminate.

Now that you are verifying there is a missing relay, I need to get the proper relay to install and test. I can put the known good ABS computer back in and test to see if the ABS works or not. Now I'm trying to figure out the proper relay to order. I was looking in my Clymer manual for a photo of the relay box for a photo of a relay box that has ABS, but I never found one. Perhaps there is one somewhere, but I never found it.

I don't know if I have further confused the subject or not. But I think I now know that I need a relay before I start working on it again.

Ed

 

[98lee]

61 31 1 459 675 RELAY - ABS/ÖFFNER/BLUE $18.86


This is the blue ABS mini relay that you are missing.

 

[heejrbmw]

This is the blue ABS mini relay that you are missing.

Thanks a bunch Lee. I have the relay on order!

ed