Cure for GS's flashing ABS lights

Q. My BMW R1150GS has ABS – as soon as the bike starts to move I could hear the noise of the ABS engaging and at the same time two simultaneously flashing red lights on thedash would go out.

Recently, though, the ‘engaging’ noise does not happen and the two lights flash consecutively instead, which is a pretty annoying distraction when riding along. If I press the ABS button then they stop flashing but one light stays on. Any ideas what the problem is and how to fix it?
Bruce Condor, email
 
A. As the wheels turn the wheel speed sensors tell the control unit that they are ‘present’ and the warning lights should go out as the ABS system is live. The ABS pump will make a noise as you pull away as the motor inside is briefly pulsed. There are some preconditions that the self test must achieve before the ABS system will ‘ready’ itself.

The battery voltage needs to be good and brake levers left at rest position, With the brake lever switches in a ‘closed’ position at rest the control unit will be checking circuit continuity through the switches. No continuity will mean that the self test will not clear.

If the rider’s handbook is available, there is a page devoted to ABS warning lights. There are two lights on the bike and they flash at different speeds and in different colours according to what the fault is. There are up to 12 combinations, even highlighting a blown bulb).

The flashing warning lights will need to be checked against this list to help identify the fault that is preventing the self test from completing. I would check sensor wires and sensors for any physical damage, but the flashing light sequence will give the biggest clue.