The 650GS has minimal electronics compared to other models. The electronics provide the functionality to reap the benefits in improved fuel economy and weight reduction but without the excessive complexity of other models.
There are only 3 electronic systems, ABS, BMSC, and Dash. The BMSC is the only programmable device with diagnostics capability limited to the ABS and BMSC plus the associated dash lamps.
It is worth considering that the total volume and weight of the BMSC engine electronics and sensors is less than 30% of the weight and volume of extra fuel needed in every refill if the electronics was not used.
Little is known about the electronics internal to either of the ABS systems on the 650GS, whether repair of the electronics is feasible is not known at this time. All of the information on the systems is in the Brakes and ABS page.
There are 3 variants of engine ECU. The first two, BMSC and BMSCII are made by Hella with a 3rd made by Magneti Marelli called the BMSE introduced on the 2013 model. Little is known about the BMSE and firmware at this time.
The engine sensors are largely the same between all models, the details are on the Engine Sensors page.
The BMSC are comprised of a 5v Freescale 68000 processor and memory with 12v output stages for the fuel pump, 02 sensor, Fan and Tank Vent Valve. All program code, adaptions and fault codes are held in non volatile memory.
Faults in the output stages of the 00-04 BMSC are repairable but it is not for the feint hearted.
Warning On EU models do not use the spare Tank Vent Valve socket under the seat to power accessories. This is a BMSC output and could generate fault codes or damage the BMSC, the current through it is monitored by the BMSC.
Information on the 3 BMS and details of the IC's used on each are in the pdf and zip files below.
Also see Other Repairs and Utilities/Diagnostics for BMS firmware and TSB information.
It is recommended to fit an earth strap to the case of the BMSE on 2013+ models.
The dash for all the models up to the 2010+ has two connectors, a 12 pin connector for the dash electronics (X9001) and a separate 10 pin connector for the dash lamps (X9028). All the dash lamps other than the Fuel Level and the ABS operate independently of the Dash electronics. PDF's with the dash pin outs for all the models is below. Fault finding for the dash lamps is a matter of multimeter testing from the dash X9028 socket. 00-09 Dash Info pdf
Little is known about the Dash on these models at this time
The firmware is not able to be updated and the capability of repairs is unknown.
More info will be added as it comes to hand.
The primary tool needed is a diagnostics system like the GS911, the basic diagnostics routines are held in the ECU's. Diagnostics tools simply activate test routines. Dash diagnostics is limited to some lamp testing.
THe diagnostics routines in the BMSC/E are more extensive than the dash assemblies with component testing.
Once the fault codes are obtained then it is down to checking continuity of wiring from the ECU sockets to the sensors and output devices. Diagnostics routines can be used to continually trigger components while checking the continuity of the wiring. Resistance of components can also be checked from the ECU sockets.
Ensure all engine sensors are tested and confirmed operational before concluding a BMS is faulty. There have been occasions where dealers have replaced a BMS only to find the fault was a sensor, particularly the crankshaft sensor.
Real time values can be obtained from the BMSC to enable analysis of the operation of components. Output is in CSV (Comma Separated Values) format for input to a spreadsheet. The skill is in interpreting the results.
When fault finding with the ignition on, use a battery charger or power supply to avoid a flat battery
Resetting of the BMSC/E is done only via diagnostics, depowering the BMS does not reset fault codes or adaptions.
It is also an urban myth that twisting the throttle 3 times with the ignition on performs some form of BMSC reset.
When replacing a BMS sensor, Fuel Injector or Fuel Filter Regulator always reset the adaption tables with a GS911. There are variations between components and it is the adaption tables which adjust for these variations.