Resolving electrical faults for some is easy and others daunting but following simple procedures can make it easy. First learn to use a multimeter to measure voltages between a wire and earth and secondly measure resistance between two ends of a wire or two pins on a component.
Thirdly identify any intelligent components such as ECU's or Dash and understand that there may be complex data communications between intelligent components rather than simple on or off voltages.
The final element is to learn the BMW color code system. It is common to all the vehicles with some small variations.
The full color code lists are in the index of the wiring diagrams, these are the main colors with explanations of their normal usage. The color code system can break down at the final socket to a component, where generic parts are sourced. An example is the ABS sensor wiring. The 3 primary wiring colors are :
Examples of the color stripe system are below
Rt/Sw - Red/White - Fused Power to Components
Rt/Ge - Red/Yellow - Power to Load Relief Relay
Gn/Bk - Green/Black - Power from Load Relief Relay
Br/Sw - Brown/Black - Sidestand diode return wires
Br/Or - Brown/Orange - Earth return from Engine Parts
Gn/Vi - Green/Violet - Power to Horn from Switch
2013+ BMS-E equipped models have fuel pump and fan relays mounted under the seat near the fuse box.
There are differences between F Series and G Series parts, the Part Nos are in the pdf. Generator Parts
It appears the G Series starter clutch has been changed with most other parts remaining the same.
The majority of the dash lamps operate independently of the dash electronics.
The method of operation of the dash lamps on the all the 650GS from 2000 to 2009 is below.
The 00-09 Dash info pdf on Electronic Repairs page has more information on Fuel & ABS lamps.
ABS - Operates via circuitry in Dash
Fuel - Via circuit in Dash with delay and latch
High Beam - Power on White wire from High Beam
Indicators - Operates across the L/R indicator wires
Coolant - Earth on Violet wire from the BMS-C
Neutral - Earth on Br/Sw wire from neutral switch
Oil P - Earth on Br/Ws wire from pressure switch
Note - See Mods/LED for LED flasher modification.
Wire 2 Flasher sockets together, connect to BMW Relay O/P & +12v to I/P.
The Dash and BMS-C have connections for both switched and unswitched power. When the ignition is turned off there will be approximately 70 milliamps current drain, then after approx 5 seconds both components should go into sleep mode. When in sleep mode the total current drain is 1 to 2 milliamps.
There can be a number of causes for abnormal battery drain in a modern machine, the main faults are listed below.
ECU's - Dash and BMS-C may not be going into sleep mode. There is no history of this on the GS.
Harness Chafing - The wiring harness chafing is known to cause parasitic drain. See Wiring Repairs.
Starter Solenoid - "Feathering" or very fine metallic fragments can build up on the solenoid contacts.
Relays - As per the starter solenoid "feathering" can build up on relay contacts. Replace the relays.
The full list of components with unswitched power is :-
Ignition Switch, Solenoid, Voltage Regulator, BMS-C, Motronic Relay, Instrument Panel, ABS, and Load Relief Relay
The safe basic procedure for finding the fault is to put a multimeter in the earth lead circuit on the battery using the 0-10 Amp connections and disconnect components one by one to locate the faulty component.
The multimeter will initially read 0.07 then drop to 0.00 if there is no abnormal drain. The multimeter can be used in 200ma range to get better readings but the 10amp range is safer for those less experienced with multimeters.