no AC charging and sudden stop while driving

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Dec 30, 2015
Rimini - Italy
Hi guys, a little help here? :shock:
I have troubles fixing my aging, but until recently, almost perfect "Zerina", a 2012 C-Zero, 16 kwh battery pack replaced under warranty in 2017 (last time I checked SOC was at 93%, I could still easily drive for 120 / 130 kms).

Zerina has started having trubles last spring. It would suddenly shut off while driving, on the dashboard: car! + battery lights would come on and "ready" would come off. I took it to the nearest Citroen dealer, they added a couple mass wires and oddly enough (for me), Zerina seemed to have come back to life. I was quite optimistic but at the begginig of summer, after one night charging (@ 3kw AC) I noticed the battery was not completely full, it was more or less at 80%. From that day on every time it would charge less, until some weeks later it would only start the process, fan would start as usual, but after some seconds the charger would quit. I could charge on Chademo though, so I supposed there was something faulty on the On Board Charger. At the same time Zerina has started to show also the old symptoms, it would shut off while driving, and that too seemed to be more and more frequent. I took it again to the shop, after a quick check sure enough the dealer told me the OBC was faulty and needed a replacement. I wasn't expecting the price tag though: 7000€ + fees, probably more than the residual value of my car, so I started searching for a 2nd hand part, which I found some weeks ago. It came from a totalled car, (just to be sure I took all the electronic boards as spare). The car was a 2013 model, I didn't know Mitsubishi had changed the design of the OBC and MCU, but with the help of this forum and the videos of Peter K, I was able to adapt the new OBC and install it. I finished this morning but now the charging light on the EVSE never comes on, the fan would cicle as usual (so I know the 220v comes in), but no charging, not just this, but on the dashboard the battery charge indicator show no bars, the diagnostic tool show a single error message: no communication with MCU. now I am wondering, is the OBC VIN coded so maybe it doesn't pass the signal?
Tomorrow I'll try and open the MCU to test the 450V 20A fuse, anyway if it is blown it means there are some problems with those boards. So second question: is it possible to swap a 2012 MCU with a 2013 model (which I have here at home), like I did for the OBC? the sockets are different, it seems on the 2013 model there are more pins on them, I am not sure if this could be done, but even if this was the case, is the MCU VIN coded / locked? I am at odds, with my little car standing dead since july, any help greately appreciated!

Hi there
Sorry to hear about your troubles. My understanding is that while the MCU is VIN coded the OBC is not, however even if you have a mismatch you would get a specific error.

What exactly is the error code? If you disconnect the new OBC, do you get coms to the other CAN nodes back? If you don’t then you may have a CAN issue introduced while replacing OBC, check the troubleshooting guide in the workbook manual (measure CAN resistance)
Thank you for your help MickeyS70.
Error codes are: U1100 and U1101

Today I checked the MCU fuse, it is ok.
Switching on the car I can hear the battery fan blowing continuously, but no battery bars appear on the dashboard.

I tried the dealer's citroen diagnostic tool. It recognises the new OBC correctly, but a bunch of control units are reported offline (basically all the 3 units under the rear passenger seat, the shift lever controller, the MCU, and the dc/dc converter inside the OBC.
There must be something on the CAN bus. I even tried to swap all 3 units under the rear passenger seat (with the spares I have obtained), but to no avail. I wonder, does the dc/dc converter just recharge the 12v battery, or is it possible that if it doesn't work those units are left without power?

I visually checked the cables and tried the connectors to see if something was loose, but everything seems ok.
In the next few days I'll try MicheyS70's suggestions and I will try to check the CAN bus (CAN resistance and cables continuity).
Is there something else I could try or check?
What is the age and condition of your 12V starter battery? has the car sat without being used for a week or more? An old, weak or worn out starter battery could cause faults like yours, and many more.

What is the voltage of the 12V with the key OFF, then with key to ON position before starting?
Hi Kiev,
The 12v battery is brand new and it's ok, it's the first thing I checked and changed for precaution (even if the old one seemed still quite ok). Problem is that the dealer unplugged it in July when the car was sitting idle in his garage, so basically all circuitry were left without power source for nearly 5 months. Do think this could have desynced the circuits?
Oh that's not good. There are circuits boards in the main pack that monitor the cell voltages (the CMU boards) that have a 12V supply that is always powered up. It is not intended for the 12V battery to ever be disconnected from the car for such a long time; it must always be kept fully charged and connected.

There are memory values that have likely been lost; it may be possible for a dealership service department that has the MUT or equivalent factory tool for reading and writing values into memory.

i suspect that the 12V is bad even if it was new 6 months ago; if it wasn't kept fully charged during the 5 month disconnect then it is likely no good anymore.
.. I wonder do your new issues have something to do with below:
(further info on

DBMandrake wrote:
“I was aware of this as it has happened to me before but I had forgotten about it. For some reason on the Ion/C-Zero it's imperative that the OBD connector of the diagnostic tool is disconnected before either shutting down the laptop or disconnecting the USB connection to the diagnostic tool.

Otherwise the un-powered diagnostic tool electrically loads the OBD-II data lines down causing a loss of CAN bus communications throughout the car for the duration that the OBD-II plug remains connected that very quickly sets a boat load of fault codes which then need to be cleared again.

The proper disconnect sequence is

1) Exit Diagbox software
2) Unplug the VCI interface OBD-II connector from the car
3) Now you can shut down windows and/or unplug the VCI's USB connector.

If you reverse steps 2 and 3 it will set lots of spurious CAN bus communication error fault codes in the car…”