Not the kind of adventure anyone wants

My last proper ride out, a local-ish green-lane, before the dreaded "EWS!"

Just before Christmas I was riding when the engine died with EWS! showing on the Kombi, leaving me stranded at the roadside. It had shown a few times previously at key-on but cleared upon retrying, however, starting the bike to head home had taken several attempts. Once recovered to home my GS-911 reported the typical "10491: Electronic immobiliser malfunction" with "no signal or value".

My maintenance plans for Christmas went out the window.

So I:

1. Replaced the battery, as I read it could have an impact and it was on my to-do list anyway (~9 yrs old) - No change.
2. Un-taped the wiring loom from the ring antenna to the main loom to inspect for the usual reported damage - None found.
3. Tried the spare key - No luck.
4. Replaced the ring antenna - No change.
5. Un-taped the main loom either side of the branch off to the ring antenna and down toward the ECU (BMSKP) - Still no damage found. Discovered that the bike seems to 'retry' every 38 secs which can make you think the wires you just moved are intermittent.
6. Tested the continuity from the RA plug to the disconnected ECU plug - all 4 wires read ~0.5 Ohms even during wire manipulation.
7. GS-911 View Key Status says (with RA connected) "The key currently in the ignition is INVALID and ENABLED. It is key number: 0". The info is the same with the spare key.
8. Un-taped the loom further looking for any damage but nothing visually wrong and there's too many wires to test individually.
9. Put a scope on the twisted-pair to the ring antenna to see if there was any activity - there was; I saw data traffic, but couldn't tell if it was from the RA to the ECU, but the ECU is ignoring it or if it was the ECU requesting info from the RA and not getting an answer. I suspected the former as the RA had been replaced. The CAN channel of the ECU that is connected to the RA must be damaged so it isn't able to read the data from the RA. I should have checked with the RA disconnected too, that would've indicated one way or the other.

2008 GSA, stripped down to investigate.

Observations

• ODO/trip reset button on Kombi does nothing.
• INFO button on left bar does nothing, but indicators, horn and ESA buttons seem fine.
• Dipped beam can switch itself on, apparently randomly (with and without GS-911 connected).
• Every 38 secs, either FUEL! or LAMPF! appear for <1 sec (EWS! disappears) and a servomotor can also be heard (tank removed, HID lamps connected).

Diagnosis

This looked to me like the ECU was partially faulty, possibly just a CAN transceiver chip, but I'm speculating. I presumed a dealer could test the BMSKP to confirm one way or the other as I didn't want to arrange a replacement to find that it isn't the cause.

Action

I called Reiten Motorrad, my nearest dealer, and explained the situation. They were a little confused by the symptoms (we ran through all the usual) but said there was a few things they could try...

While reassembling the bike to get it to Reiten, my mate was relaying the events and symptoms to his pal at Lind Motorrad (out of hours too!). Once my mate's mate had had chance to discuss it with his colleagues, I got a message saying they suspect I may be correct in my diagnosis; ECU. Arse. ECUs are expensive and I was kind of hoping...

I checked Reiten could take the bike if I turned up with it in a van on Saturday, no-prob-Bob, so I made the arrangements.

Outcome

Just a few hours after drop-off my phone rings; "it's definitely the ECU, I'm afraid". They happened to have a same year bike in on part exchange and swapped it's BMSKP into mine and the problem disappeared. The BMSKPs are coded to the VIN so can't be swapped and left in but can be used to help fault finding.

Bad news is a replacement part is £750, plus a bit of labour. Ouch! (I didn't have to sit down too quickly as I'd read the same when researching the fault and had prepared myself.)

Future

I asked for my old ECU back so I could attempt an autopsy and perhaps have a spare.

If they let me have it (can't see why not) and when/if I open it up, I will make another post of any findings.