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Old 02-26-2014, 10:57 PM   #3226
Cam Killer
marchyman's Avatar
Joined: Jun 2005
Location: SF Bay Area
Oddometer: 7,615
Originally Posted by daveburton View Post
I have a new (2 actually) antenna and have tried to start the bike with them. I'm getting an intermittent fault that is getting worse for sure. The antennas did not help although I thought it was a bit better, ie frequency of good starts improved a bit.
When the ignition is turned on the engine management checks for a known key. It sends some kind of signal that is radiated by the antenna and reads the response from the key. If a valid response isn't received you'll get the EWS warning. If the response is valid the system lets you start the bike and the circuit will not be checked again until the next time you try to start the bike.

That leads to several possible failure modes:
  • There is not enough battery power to run the BMS-K
  • The BMS-K is not sending the signal due to an internal failure (unlikely, IMHO)
  • The signal is not getting to the antenna (wiring?)
  • The antenna is broken (but you say the spare is doing the same thing)
  • The key is broken (do you have a spare key?)
I'm guessing that your antenna was never the problem. I'd swap keys first, because that is easy. Then I'd start tracing the wires looking for a place where cable ties and vibration have done some damage. That is not an unknown issue with some bikes.
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