ABS Error - missing pin?

[20774]

Threads with "ABS flashes at 4Hz" mentioned:

https://forums.bmwmoa.org/showthread.php?49729-ABSi-problem-on-R1150GS-2004-model

https://forums.bmwmoa.org/showthread.php?71978-2003-R1150RT-Rear-I-Abs-out-and-Flashing-Lights

https://forums.bmwmoa.org/showthread.php?69002-ABS-flashing-lights

https://forums.bmwmoa.org/showthread.php?88680-ABS-warning-light

 

[johnwraystewart]

Thank you, 20774. I just read through all of those threads. I'm not filled with hope right now, I'm afraid.


I did find last night the front ABS fluid was a little low, so topped it off.

Alas, symptoms were same thing this morning.... after a few miles, Gen ON and ABS 4Hz.

Next step is to check for issues with the rear brake sensor. What doesn't track for me that it'd be an electrical issue is:

- It's always fine after sitting a few hours
- It always starts back up after riding a few miles

I'd expect it to be more random, if I had a pinched/broken wire someplace.

 

[m_stock10506]

Thank you, .................... What doesn't track for me that it'd be an electrical issue is:

- It's always fine after sitting a few hours
- It always starts back up after riding a few miles

I'd expect it to be more random, if I had a pinched/broken wire someplace.

I am not familiar with the iABS, so take this with that in mind. Lots of electrical problems are heat related. A component or a solder joint heats up over time as it is in use. When it gets hot enough, the component fails or the the solder joint separates. Electrical problems are unfortunately not as simple as a completely open or shorted circuit.

 

[johnwraystewart]

Again, thank you GSAddict.

I did just find this, which is super-helpful:
https://www.yumpu.com/en/document/v...lectrical-schematic-p-1-of-3-v31-1-mac-pacorg

... although I don't see yet how to tell which wires are which in that connector (7 vs 41)

To answer my own question, this looks to have the Secret Sauce from https://www.mac-pac.org/tech/electrical-diagrams/:

https://secureservercdn.net/198.71....014/09/R1150RT-iABS-Electric-Diagram-V1.0.pdf

 

[johnwraystewart]

An update:

- I took the bike in for major service the other day (long scheduled - shop is very backed up) - fluid change, valve adjustment, alternator belt.

- They did say they DO have a code reader, so my plan had been to ride it until the error recurred and then take it in.

- Previously it had been consistently erroring out after about 4-5 miles, then consistently fine when I come back after a few hours.

- Well, since getting the bike back, I've been taking on progressively longer trips, and so far, have yet to see an error message. I probably did ~200 miles or so this weekend, with no problems.

Hypotheses:

- Perhaps related to heat; it's been in general cooler around here since the last error messages.

- Perhaps related to flow of brake fluid, and perhaps the error was an overpressure situation (one potential issue I saw mentioned in a related thread). Maybe there was gunk in the filter, and it's now worked itself out?

I had bled all the fluids as part of replacing the brake lines, of course. And some of it was fairly gunky.

Knock wood.