An ABS fault on startup can occur when the system does not have enough energy - a fault is indicated by ALTERNATING flashing. Synchronized flashing of the two lights is normal and will stop as you drive away - you will hear the system make a "kerchunk" sound and the lights will go out. The lights will not go out until you ride a few feet and initialize the system.

If you are getting ABS faults, then you are going through your start-up procedure too quickly. When you start your bike, give the total system more time to initialize. The ABS system, fuel pump and Motronic all need a lot of juice. A good rule of thumb is to turn on the key, let the ABS lights blink at least three times before hitting the starter button. If you slow down your startup procedure in this manner, your faults will cease. If not, then you have a poor battery or other electrical system problems. See your mechanic.

Ernesto B. Pantangco <ernestbp@i-manila.com.ph > agrees but points out that the problem could be related to the starter: "For RT owners who experience intermittent problems with their ABS when starting their bikes (either cold or warm), the source of the problem is low voltage, approximately lower than 9.8 volts (BMW internet riders 1100 faq file). This can occur from a battery that has not been charged from use or thru a battery tender; or, as what happened to me, the starter motor was draining more current than expected.  A simple test would be to connect a voltmeter to the battery terminals. If during starting, the voltage drops below 9.8 volts, check battery condition. If battery is fully charged prior to starting, check the voltage and current drain of the starter (per BMW repair manual page12.11), the voltage should be 10-11 v and current drain (measured from + side) should be between 80-150 A. If the current drain is more, have the starting motor checked. It is easy to locate (bottom left hand side after removing the side panel) and detach since there are only two allen screws. Disassembly is easy if you are an experienced mechanic. There may be a loose magnet(s) attached to the rotor. If so, an experienced mechanic could reattach the magnet(s) and secure the rest.