Handlebar removal requires removing the cowlings and opening the electrical box then extracting the pins from the 4 pin socket connecting the grips. A time consuming exercise which can lead to pin breakage.
When a fault occurs the wiring is also difficult to test without time consuming removal of the cowlings.
A solution which has proven reliable is documented below as well as wiring diagrams for the standard wiring and the modified wiring complete with color codes, electrical specifications and fault finding procedures.
This modification can be done on all the 650GS year models.
Grip Element Resistance - 9.1 ohms
Half Heat Load Resistor - 2.5 ohms
Power Consumption @13.8v - 42 watts
Half Power Current @13.8v - 2 amps
Full Power Current @13.8v - 3 amps
Single Spark Switch - 3 pos, centre off
Green/Black - Power from accessory socket to the switch
Black wire - Full power from switch to 4 pin grip socket
Orange wire - 1/2 power, switch to grips via load resistor
Brown wire - Earth from grips to socket in electrical box
The 1/2 heat load resistor is 300mm of resistance wire
Remove cowlings, electrical box cover and battery
Disconnect heated grip wiring socket (4 pin or 2 x 2 pin)
Pull the 2 cables from the heated grips back the steering head.
Route the cables down the LHS behind the steering head and in
front of the electrical box to the RHS outside of electrical box
Mount 4 way screw block to the RHS of electrical box
Connect the grip element wires to the RHS of connector block.
Extend heated grip harness wires to RHS outside of electrical box
Cut the BMW plug(s) from the heated grip wiring harness
Connect the grip harness wires to the LHS of the connector block
Build and fit wiring cover from jiffy box as per diagram in wiring pdf
Refit electrical box cover, battery and cowlings
Variable temperature controllers can be wired in to replace the 1/2 heat resistance wire. Basic information on the types of controllers available is in the pdf. The simple digital units are the best to use. Heated Grip Controllers
1/ Remove RHS cowling (optional) and connector cover, use multimeter on the heads of the screws to check resistance of the elements (across brown and black wires). The resistance while connected should be 4.6 ohms.
2/ Disconnect the brown wires on the LHS of the connector block to test the resistance of the individual elements.
Each element should be 9.1 ohms (across brown and black pairs). Reconnect the brown (earth) wires.
3/ Turn on ignition and heated grips, use multimeter on the heads of the screws on the LHS to check for 12v
This basic procedure can also be used at the sockets in the electrical box for the standard heated grip wiring