EWS is BMW naming for the immobiliser bit that make theft of modern vehicles harder - they play up all day long on Honda bikes, Mercedes cars and many other vehicles as they age. Regardless of whether you can turn the key to operate the switch and or force the electrical elements to connect up (like Hot wiring) without the valid authorisation signal from the key reaching the engine management computer, its never going to let the engine run
below some info and if you need to change here was a good write up of how easy it is
to give quick heads up - the ring antenna is about 50 quid from your main BMW dealer and according to them makes the fuel strip look reliable...
To fit the new part, the ring antenna lifts off over the top of the ignition switch - so you need to remove the whole ignition switch / ring antenna from the top yoke from down below - its held on with two stupid security bolts (and if you want to do this the BMW way you need to buy two new bolts from the dealer with the antenna and the special BM tool (No 510531) to do them up - you don't want these bolts as its no longer a side of the road repair - if anyone can find and get at these they'll be stealing the bike anyway
BMW instructions say to drill a 4.5m pilot hole 6mm deep then use an 8.5 mm drill so the bolt head falls off, and after dropping out the switch, extract the two bolt studs (ignore BMW...)
these days you can buy drill bits with the 1/4 hex shank like the screw driver tips use - buy a 5mm one from screwfix, and also buy a sacrificial T25 torx driver bit and a 6" long screw driver tip extension bit for your cordless drill - and get two 8mm x 30mm cap head bolts. Other stuff a hammer, a magnet on a stick and for good measure some masking tape to hold rubbish back / protect the bottom fork tubes).
1) Up top - pop off the two tiny torx bolts nearest the cluster and get the plastic trim cover from the base of the ignition switch and remove the pair of wiring connections and get them tied out of the way
2) Now down below looking up get your magnet somewhere up in the gods near the bolt head and tape it from falling out. Forget a center punch - the soft strange security bolts have a hole that centers the drill for the thieves to take you bike anyway. Now using the 6" screwdriver tip extension and the strange drill bit, a battery operated drill fits quite nicely just off the mudguard and drill a 5mm x 5mm deep hole in the center of each of the two bolts, (trying to use a conventional short drill bit will likely have you trashing brake and clutch hoses, doing looms and swearing a lot)
3) get your sacrificial T25 1/4" tip and place in the 6" driver extension - now reach up with a hammer and tap the torx bit into the soft bolt head - they are going to be about 20lb ft tight and the loctite makes them tight all the way out
4) with the bolts out the ignition switch can be wiggled past all the detritus around the headstock. On the bench its obvious a little persuasion with a small pick will allow you to unclip the ring antenna from the switch
5) clip on the new antenna, wiggle the switch back up ensuring nothing is trapped - with BMW even using nice washers to go with your smaller headed cap heads
round of applause to Steptoe for his torx driver top tip...
(obviously a few cable ties to get at the part need to be removed and replaced afterwards)
