From Ian Hartley on UKGSer, who traced the wiring on his bike to try to solve my issue...
Originally Posted by Ian J Hartley
This is where it's likely to get confusing, because the layout for the R1150GS single spark, and the twin spark are different.
On the twin spark
Fuse 8 does only the low beam and instrument lights.
Fuse 9 does the ABS warning.
On the single spark
Fuse 8 not used
Fuse 9 not used.
At least we know the fuse wiring for the twin spark.