The basic braking system is common to the range but the ABS system is different between the CS, GS, Dakar and G650GS.The basic differences are set out below. Further information will be added as it becomes available.
Fault finding procedures for ABS are not well documented. The ABS dash lamp can indicate error messages but the meanings are unknown. The most common fault is scuffed or damaged sensor cabling so start with checking the cabling. There should be 1v AC output from the sensors when a wheel is spinning.
Brembo part numbers can be specific to the OEM, so the same part may have multiple part numbers but be the same part. The rear master cylinder with BMW cast into the alloy is typical. The part No is 110.4362.41 The same part without BMW stamped on it is 10.4776.50 which is listed to fit Ducati, Aprilia, Laverda and Moto Guzzi models. It is worth looking around, the price differential can be significant. Gowanloch supply many Brembo Parts for Ducati.
The shallow head rear disk mounting bolts should be considered a use once item. They are thread locked and can shear on removal. When removing the disk application of heat to release the thread lock is recommended.
The OEM brake hoses perish and break up internally blocking fluid lines, master cylinders and possibly ABS. Check hoses periodically and replace where perished. See the brake line info pdf above for Part Nos and lengths
There are wiring differences for the brake lamp between ABS, non ABS models and the ABS types. Where ABS is fitted the input circuit to the ABS system results in a voltage at the lamp when the brakes are not operated and leads to confusion in fault finding. The diagram here shows the wiring differences between the variants in wiring and provides some simple fault finding test procedures. Brake Lamp Wiring pdf
The switches are simple micro switches which cant be repaired. Check with a multimeter, replace if faulty. Bending of the rear switch actuator lever is critical
The majority of parts are specific to the CS. The front sensor ring is common with the GS.
The pressure modulator looks the same as the GS but is a different Part No.
ABS parts are common between single and dual spark models. The GS and Dakar are different modulator Part No's. The on/off switch and dash lamp wiring of the GS and Dakar is different and there are likely to be changes in ABS sensitivity. The early 2001 models used unbalanced shielded leads to the sensors with later cabling being balanced presumably for improved noise immunity.
The ABS pressure modulator is the ABS8M system and is a completely different unit to the F650GS with
different mounts. Only the sensor rings are common to the f650gs.
The technical details are in the pdfs below.
Bleeding the ABS8M is the same as a non ABS system.