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Twizy SERV issue - latest firmware?


I've had the SERV light intermittently come on for the last month or so, and have been trying to diagnose the problem. The symptom is the SERV light illuminating along with a slight but noticeable decrease in available power. It typically happens within about 5 minutes of starting out, and sometimes goes out on it's own but mostly stays on until the end of the trip. It's always not illuminated on restart of the car.

I swapped the 12V battery today (didn't think that was the problem but wanted to rule it out). Gave it a good charge and the problem is still present.

Digging a bit deeper I reset all the profiles (I have OVMS v3), looked at various logs and still had the problem. I started to see a pattern where is *seems* to happen shortly after a reasonably (>5-10s) period of regen (so, say, deceleration from 40mph to 20mph).

I also noticed that the latest OVMS firmware is 25th Sep, and while I can't say for definite it was *around* this time that I started seeing the problem. (I'm running 3.2.005-42-g0e8f7306/ota_1/main (build idf v3.3-beta3-774-g6652269e1 Sep 25 2019 18:38:03))

So I disabled CAN writes in OVMS, and it seems to have fixed the issue. I've only done one drive since, but it was quite long and the SERV light stayed off the whole time - I haven't been able to do that for quite a few weeks.

So, is there anything in the latest firmware that could cause a SERV issue after a bit of regen? I have got the "Enable Auto Power Adjustment" ticked and Kickdown enabled.

Happy to re-enable CAN writes and grab logs etc if they'd help (just let me know what you need).



dexter's picture


there have been no reports of such issues with the 3.2.005-42 release, so I think that's more likely a hardware issue.

And your description sounds like an issue my Twizy currently has: the brake pedal switch is sometimes triggered by the pedal weight alone, which happens especially on deceleration and on bumpy roads. That also triggers a short flicker of the SERV light, and as the switch triggers the transition to brake recuperation level, it may feel like a loss of power.

My "temporary" fix to this is a package rubber strap running from the hand brake lever to the brake pedal. You might give that a try.

Another option is a fault with the motor speed encoder. That's also been happening some times to users, but cannot be fixed with a rubber strap.

You could first of all check the SEVCON diag logs and the DTC store for anything unusual. The faulty brake pedal signal seemed to trigger DTC 4/21 on my Twizy, but that could also be related to the brake light hack.


Thanks for that - really

Thanks for that - really useful info. I had wondered if bumpy roads were causing the issue too. My symptom isn't a mere flash of the SERV light though - it's always on for at least 1-2 minutes, and usually once it's on it stays on.

The reported DTC codes are:

DTC report: 3 stored, 1 present
#01: 4/21 rev0 G1 INT MEM Ef
@ 3270km 0kph SOC=89% BV=14V TC=0 IC=180
#02: 2/56 rev0 PRESENT(156x) G1 INT MEM Ef DNS
@ 3371km -1kph SOC=67% BV=14V TC=0 IC=138
#03: 4/64 rev0 G2 MEM Ef
@ 3593km 0kph SOC=77% BV=13V TC=0 IC=43

So there is a 4/21 but it's quite old (>300km ago if I'm reading right?). Do you have any idea what the other ones are (2/56, 4/64? - is there a list somewhere or is it proprietary Renault info?)

However, I did my second reasonably length journey today with the OVMS CAN Write set to OFF and didn't get the SERV light illuminating. It's not enough test time yet, but if I don't see it over the next few days of driving I'll re-enable CAN writes and see if it comes back.

dexter's picture
Sorry, I don't know the code

Sorry, I don't know the code meanings, they haven't been disclosed by Renault.

Please report your test results.

Also check the module log with v-twizy level set to debug or verbose.

Seems sorted...

Just a quick update. I enable loggin for the Twizy module and drove another couple of days with CAN writes disabled and no SERV light appearing.

I then re-enabled CAN writes and have done at least 10 drives now with no sign of the SERV light.

So whatever was causing the problem _seems_ to be sorted... Very odd!

Anyway, just wanted to let you know and I'll get back on here if there's anything more to report (hopefully with logs if it happens again!)



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