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Discussion Starter · #1 ·
Got a potentially big problem with my 2017 Duke and could do with some input please.

I rode 50 miles to work on Sunday morning with no issues. On leaving work the bike stalled several times after starting, as soon as I let go of the starter button. Eventually got it going, but then while riding the emissions light came on and bike briefly slowed down before recovering. About 25 miles into the ride the engine cut out completely and needed restarted. I got it home and some brief investigation led to me hearing the fuel pump relay clicking a lot. I checked it and it seemed OK.

Monday night the bike would start but then cut out after about 20sec running at an idle of 3000 rpm. Also on Monday night I discovered that manipulation of the cables near the air temp sensor cable would affect the fuel relay clicking. I also at one point heard a rather nasty sound that I think was another relay clicking very very quickly.

At this time I checked the fuses and all were good, they still are. When I finished on Monday night the bike would still prime the fuel pump and would start, before cutting out.

On Tuesday evening I went to continue my investigation into the problem, but every time I switched on the bike, the fuel pump wouldn't prime, and seemed no power to anything except the display which after 15s brought up a red banner saying ecu failure. It's been like this since.

I've noticed also the indicators do work, but are flashing too quickly. Also, the "side stand down" message is not being displayed.

Anybody have any ideas? Am I really looking at an ecu failure or could it be a bad earth? I'm need to find where the earth connects to the frame. I've also tried to read the fault codes but the obd can't connect to the ecu anymore.

In a strange twist of timing, i had just ordered a 2020 rc390 when this happened (it came today and is awesome) so I'm not bikeless but really want to get this fixed ASAP.

I'd really appreciate any ideas people may have. I have also taken the battery out, charged it and refitted it but no joy...
 

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Start off with inspecting your ECM connector, a loose ECM connector does tend to throw errors that weren't in the first place. Secondly, make sure the ECM connectors are WD 40'd so you know you're doubly safe, this is irrespective of a good or weak or bad ECM, this is worth a try.

ECU failure on the newer models throw due to two reasons primarily, a battery that isn't providing enough juice to the components and secondly a loose ignition coil input connector and thirdly and obviously a shorted ECM (happens when your luck runs out pretty sooner than you intended)

Interesting to note in your post you've mentioned

"Also on Monday night I discovered that manipulation of the cables near the air temp sensor cable would affect the fuel relay clicking. I also at one point heard a rather nasty sound that I think was another relay clicking very very quickly"

Now, when you have a nicked wire i.e shorted wire grazing against each other, this tends to cause all sorts of chaos, stalling, misfiring and the ensuing headache. You've mentioned you've fiddled with the air temp sensor cable, can you explain where exactly you fiddled? The intake air temp connector wire is present on the throttle body, is this the wire you fiddled with? If not, your issue is somewhere else.

Pinpoint the exact location or share an image of the part of the bike where the relays go haywire when fiddled with that can give us a starting point. But do check the above and let us know it it transpired. Good luck
 

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Discussion Starter · #7 ·
Motor vehicle Automotive tire Hood Automotive design Bumper


B7ACKTHORN

Thanks for your comment. The top arrow points toward the air temp sensor harness which moving about had some effects on the relay. I know the cable is routed wingless right now but I put it back on like that for a quick test.

The lower arrow points towards the harness I pushed on that led to both the relay stopping its chatter and the strange sound I heard that could have been a relay or possibly some kind of arcing...

I'll get the tank off and take a look at the earthing around the ecu, also to check how wet everything is.
 

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Discussion Starter · #8 · (Edited)
OK, so far I've checked, sanded and cleaned any of the grounding points I can get at, as well as the battery terminals but no luck. I've also tried a new battery, but still nothing happens, just an ecu warning.

One thing I have noticed is that the display no longer reports that the stand is down. I've never had that problem before and I'm wondering if I'd the sidestand switch could be shorting and causing the problem. It seems a bit odd that a bad switch could do that, but I read on here that it connects right into the ecu so if its giving a strange reading maybe the ecu is reporting a fail?
 
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