If you leave the grips switched on and there's
absolutely nowt in the left one its probably a broken wire somewhere - with any luck not in the grip itself, but in view under your bars somewhere. I'm not sure how the oem ones work, but it might be possible to swap connections left to right to test if the actual left grip is working??
If not, and you go for new ones, bear in mind you can get a bit of xtra ooomph to the grips by wiring direct to the battery, or better still to an extra fusebox : eg 3 circuit solution, here
http://www.easternbeaver.com/Main/Produ ... rcuit.htmlusing its built-in relay, fuses, thicker wiring, switched with the ignition etc (and you can plug in other electrical goodies!)
I've just last weekend fitted some new Dr Bike heated grips to the 3CS and both sides get almost equally toasty. I tried to put tape around the left one but gave up, it kept scraping off as was putting on the new grip...so as it turns out, tape not needed on mine. They got too toasty on a ride in about 5 degrees cent. a couple days ago, on a 75 % power setting.
