Sevcon reset

My Stop warning light on the dash comes on 5 sec after ignition on. The Sevcon green led flashes 5 times which indicates an open circuit motor but the motor is fine and properly connected.
A few days ago I powered up the Sevcon with the motor disconnected to check the battery SOC. Can anyone tell me if this fault code lockout is latching as that would confirm what is going on. If so what would be the cheapest way to get it reset?
Any advice appreciated.

Is the motor definitely reconnected correctly? Not sure if the sevcon latches errors like that but someone like Kenneth Neilsen would know, or Jeremy from knows about programming some sevcon models.


Thanks Gary. Yes I checked continuity of the motor from the Sevcon terminals and phasing is correct going by the wire sleeve colours.

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In my case the 5 flashes reaction with stop was an immobiliser issue…hi Pat!

Now moved onto the next stage. Still no success. Mincu_Mircea it certainly looks like the same as your problem.

I purchased an OVMS and I can now see the detailed fault code 0x5143 :

The Sevcon appears to be complaining about a peripheral device which I assume to be the dashboard. There are no dtc’s when I show a dtc report with OVMS.

From what I have heard, the dashboard for some reason has to handshake some kind of ID (such as the VIN) with the Sevcon. When I got OVMS to show the VIN stored in the Sevcon, it came back blank. I was able to load the VIN using a "metrics set " command and it seemed to have stored when I used “metrics list”. But the fault code still came up as before when I turned the ignition key on.

I have now run out of ideas. It disappointing as I am sure if I get Renault to fix it they will upgrade my old firmware from 2012 and I will loose the ability to configure it.

Renault performed their diagnostics today. They first thought it might be something to do with key programming but that didn’t fix it. Then they concluded it could be a wiring fault by interpreting their diagnostic tool and have requested diagrams from Renault.

In order to proceed further, they will start charging on an hourly rate. Obviously they can neither guarantee to find a solution nor estimate how long it might take. I cannot agree to this open ended arrangement which could cost me thousands and so I shall collect the car tomorrow.

I am disappointed the Renault dealer could not offer to reprogramme the Sevcon as a low cost experiment. Not sure what to do next.

I would suggest finding your nearest hevra independent garage near you rather than dumping hundreds of pounds with a main dealer.

Might be worth a shot

Thanks for that. I’ve not come across hevra before.

Saga complete. Twizy alive and kicking.

I have to eat humble pie and acknowledge that Renault were correct in their suggestion of a wiring fault.
Swallowing my pride, I pulled out the Sevcon connector yet again to inspect the state of the contact pins. Looking into the connector pins on the Sevcon, I spotted a glinting thread of copper wire lodged between two pins. (see photo). How this had stayed in position while trailering the car to the dealers, I don’t know. But it was definitely the offending article.
Removed it with some tweezers, plug back in, turn the key and bingo… All back to normal.

During the rebuild I had added a fused outlet from the Sevcon 48v input using some heavy cable twisted from very fine strands. A tiny piece of this must have dropped in the connector.

With this conclusion, I also have to retract my theory that the Sevcon, dash and bms can somehow lose their identity when disconnected for some time. That did not happen in my case.

Really looking forward to that Monday morning commute now for a change!!
Me and my Twizy.


Nice one !

You were lucky not to blow anything up , good news :grinning:

See a friend …disconnect all the cables from the sevcon and on the plus and minus terminals turn on the consumer to discharge the capacitors inside the sevcon. Be careful. Or… someone who knows how to discharge capacitors That’s all. Good luck?

I won’t ever suggest to connect plus and minus! not! in no case !!!
!!! Much too Dangerous !!! DO NOT DO THIS !!!

I think Dimitar was saying

“Disconnect all terminals and disconnect Plus and Minus terminals, then turn on the consumer to discharge the capacitors inside the SevCon”

Agreed…NEVER put + and - together and then turn on!!! That only makes ‘Magic Smoke’ :skull_and_crossbones: :boom: :thought_balloon:

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If so, Iam sorry for the misunderstanding. Just telling to be safe at first place since non-professionnals are reading those threads and could make risky/dangerous mistakes.

In another hand, to descharged a capacitor you need to connect a load or shortcut the poles… if of small capa (not much of power in)