EWS is a failure of the ring antenna / signal / power round the lock barrel?
see below, replies from ukgser forum
--
I had exactly the same problem on my '07 1200, which turned out to be a fault in the permanent live 12v wire to the ECU. Simple fix by wiring it direct to the battery.
You need to check the permanent live, the switched live and continuity of the 4 wires from the ring antenna to the ECU. Other on here have reported your symptoms which turned out to be a broken wire around the headstock.
Here is a copy and paste from the thread I found, written by someone cleverer than me at auto electrics, and which is about a faulty F800, which led me diagnose the fault. Best of luck!
Disclaimer: I am no expert. Take the below as exactly what it is: ramblings of a random bloke on t'Internet. It is a pointer to start googling and investigating further. My motive is only to offer info to try to offer some info to help fellow bikers.
So, that out of the way, EWS (Electronische Wegfahrsperre) can come up as an error for many reasons, but thinking logically... Simplistically speaking, the bike key holds a passive "chip" inside it with a code, it goes in to the antenna which [given that the electronic power is there] agitates the key chip and "reads" the code off the chip, sends it to the ECU, which, then, compares it with the stored value and allows the bike to be started if they match. So, components involved : Key, antenna, some wiring, ECU [and indirectly the battery].
So... if the low-beam stays on, there is no whirring from the idle-actuator, no pulse on the fuel pump and no gear indication on the LCD... those symptoms are the same as it the ECU [BMSK-P] was actually completely disconnected. It would then not be illogical to think that the ECU is not booting up. If you can use a multimeter, you can do some basic tests. Head to the smaller of the two ECU connectors under the seat. Disconnect it and do some continuity/voltage tests. If I remember the pinouts correctly (let me know if they are not as expected and I will double-check/correct the post for future reads):
1) Firstly, check that you are getting power to the ECU. You should have the battery voltage [~12V] across pin-3 (-) and Pin-6 (+). (Pin-34 should be the switched +12V [i.e. ON when IGN ON]). The belts-and-braces method is to wire a consumer (like a small automotive (12V) light-bulb) to those to check for the solid current under load.
2) Check you are getting good earth too.(continuity to the frame/engine/battery(=) @ pin 3) may as well check the brown cable going from the battery(-) to the engine on the left side, near the starter.
3) Since you are already at the ECU connector, If you have disconnected the ring-antenna, you may as well check the continuity to the ring antenna; Although that is unlikely to be the problem at this stage, If the theory is sound and the ECU is not booting up at all.
Pins 1234 @ ring antenna should have continuity to pins 8,43,55,57 on the smaller ECU connector, respectively. Numbers are cast into the connector but are very small. Top-tip: Use your phone camera for magnifying if your eyesight fails you in this endeavour.
Ensure that there is no continuity between the ring-antenna connector pins too (in case of cables chafing against eachother)
[You may need some pins to insert into the connectors if your multimeter probes are too fat.]
If all of this is as expected, chances are the ECU has a problem and is not booting up...
Hope that helps someone...
----
My 2007 R1200GS has the dreaded EWS failure message on the dash. 82k on the clock.
The fault occurred on going to the bike in the garage, last time out it ran perfectly.
It also lights up the headlamp and there's no neutral light when the ignition is switched on. GS911 states it can't connect to the ECU.
I've already run one thread on this, thanks for the replies and advice, one last search for tips on what to check before I have to hand it over to someone more knowledgeable than I or potentially scrap it, which I really don't want to do as I've had this bike from new and its part of me.
So Far I have:
Tried a different ring antenna, no change.
Tried both keys in the ignition switch.
It has a factory alarm, no low battery warnings and it does still activate from the remote. It doesn't seem to automatically deactivate with the ignition being turned on, but then I suppose it needs to "see" the correct key is being used. It does deactivate from the remote.
Peeled back the loom, looking for a broken wire, nothing found.
Done continuity tests between the 4 wires from the ring antenna to the smaller of the 2 ECU connector blocks and all 4 wires are OK.
Tested that is power reaching the ECU. The permanent live has 6.7 volts, the switched live gets full battery power, 12.7 volts.
Battery is good and has been kept fully charged whilst I tinker with it.
And finally I sent the ECU for testing to ecu.de who gave a clean bill of health.
So I'm at my wits end where to go next, I don't mind spending some money on an auto-electrician but with the mileage it has it's not worth megabucks.
Any further things to try I've missed out?
Any auto-electrical geniuses out there in the West Midlands area?
----
OK lets go with the ring antenna and ECU are ok.
so you need to look at the other interactive stuff - pic 2
Thats giving you some other avenues to eliminate
Is the bike getting a neutral signal ?
Is the kill switch working and sending the right signal
Likewise the immmobiliser.
have you done the handlebar wobble to eliminate that ?
have your tried removing the immobiliser from the circuit and seeing if that works?
bypassed the gear selector to eliminate that ?
bypassed the kill switch ?
----
The immobiliser and the Alarm are two seperate items. It’s possible to completely disconnect the alarm module and terminate the canbus connector with a terminating resistor. BMW part No 61137668405 is a reasonably cheap can bus terminator, allowing for easy plug in. But you can use just a really cheap 120 ohm resister across the canbus terminals. This is really for information, you can try it, but my guess would be your EWS fault will still be present.
From what I can gather, if the Ring Antenna has been replaced and the ECU has been tested off the bike and is serviceable. Then the fact that the GS911 cannot connect to the ECU when it is on the bike and connected, would tell me that there is a wiring fault somewhere.
I would start by going around all the modules that feed to the ECU, disconnecting each in turn to see if there is one that could be faulty enough to drag the whole ECU down.
Good luck.
---
it's fixed!
I scotchlocked a wire direct from the battery to the red permanent live wire to the ECU to give it the full voltage (pin 6 on the small connector block), switched on the ignition and EWS message gone.
Neutral light back present and correct and headlight not coming on when it shouldn't.
So it looks like that mystery loss of voltage has been the cause all along. Just like the starter issue I mention in Post #9, the wiring diagram shows those permanent live wires running direct from the battery but clearly they go via something that over time deteriorates and causes the voltage to drop.
As the bike is well and truly stripped, I decided to quit whilst I was ahead tonight and will put it all back together another day, with fresh eyes, along with a more permanent, neater replacement for the scotchlock. So I haven't tried to start it as yet but fingers are well and truly crossed that now the EWS message is gone, it should fire up OK.
Thanks everyone for your help, I am truly grateful.