ABS Modification

[Kaltzg]

This weekend I performed the ABS-II Low Voltage Fault Modification posted on the Internet BMW Riders Site. My 97 1100GS has always had a bit of a problem initializing the ABS system especially when the cold weather sets in. It has never been a big problem, but irritating none the less. Quite often upon initial start-up the ABS wouldn’t set. I’d run the engine for a minute or two, shut it off and restart and everything was fine. I replaced the battery, checked the alternator output voltage, and all the typical checks and nothing ever really fixed the problem. If I left the bike on a charger overnight the ABS would set every time. I ride my bike every day, so I didn’t want to have to mess with the charger every night. This mod delays the ABS check until after the starter is done doing it’s job and the alternator is up to speed.(a more through explanation on the site) It took a couple of hours to complete and the addition of a $5.00 relay. Now, every time I start the bike and roll off, I enjoy that clunky, grindy, chatter of the ABS setting. Well worth the time and effort IMHO. :thumb

[bmwmick]

Gail,
I'm sure most folks are wondering what you are referring to. I added the URL:
http://www.ibmwr.org/r-tech/oilheads/ABS-II_low_voltage_modification/index.shtml

[BubbaZanetti]

good to hear. i've never encountered the problem unless my bike has been sitting, off the tender, for several days or weeks in the winter. i love little modifications like this. :bikes

[Kaltzg]

Gail,
I'm sure most folks are wondering what you are referring to. I added the URL:
http://www.ibmwr.org/r-tech/oilheads/ABS-II_low_voltage_modification/index.shtml

Mick
I just made the connection (duh) thanks to you and Brian for the excellent write-up. You did a great job. Good explaination of the problem and even better step by step instructions.

Thanks Again!

[bmwmick]

Gail,
I like to experiment. :) All I did was test and document the idea presented by Asko Paakkinen in Finland. Once I had it installed and tested for several thousands of miles, I made it public.

Bubba,
Your R1100S has a different ABS Hydro unit and I am convinced that BMW changed the initialization routine so that your ABS is not as prone to the low voltage faults. My son had a '99 R1100S and we never experienced the fault, even with a 3 year old battery.

[DuaneJohnson]

I have a 96 R1100RT and my wife has a 98 R1200C and both
have the ABS problem after the battery ages. Could you direct
me to the article on the ABS mod.
Duane

[bmwmick]

I have a 96 R1100RT and my wife has a 98 R1200C and both
have the ABS problem after the battery ages. Could you direct
me to the article on the ABS mod.
Duane

Read through this thread again Duane. IBMWR link above

[jflower]

I was getting ready to do that mod on my 95 1100GSA because ABS always failed startup test. It does make sense to let things stabilize before doing electronic tests. I took it to one dealer to tell me what the problem is ("no clue, but electronics works"), and asked the service mgr of another one for advice ("bring it in & pay us $$/hr to look"). But then I stopped in a small repair shop in northern Colorado that some people on ADVRider recommended (beemersandmore.com). It took them all of 20 minutes (and $20 labor) to make the problem obvious. A battery load test showed it was only supplying about 6V during starting. This was a fairly new battery, put in by the previous owner not long before I bought it a year ago. They told me that while most batteries will start a BMW fine (it did!), only some have the capacity to hold voltage up during the start. The ABS electronics needs about 10V to run its tests. The new battery fixed it. And yes, I do keep in on a BMW current-limited trickle charger. It's not hard to do on this one -- just use the accessory plug.