A lot of OBCs failing

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Active member
Jun 29, 2020
Køge/CPH Denmark

I am now up to five failed OBC in my garage.

With the newest one, the car have the following fault codes:

I have opened up the OBC and found no direct visual defects

I read the newest update on the thread:

I will try to test the OBC relay as fast as possible.
The 12V AUX is ok
The HV Battery is down to 0% SoC (not my doing) and maybe therefore I get the error for an EPROM in the battery and it will not go into ready.
I will check all connectors when I get back to the car and also try to disconnect the AC pump.

However I am at a stand still because all these OBC´s have the same error code (P1A39) and not one of them will run within a car, even as the snubber caps and other circuitry looks fine.

If I am to get some idea on how to continue and find the failure, I would send you all the chocolate and/or wine you could dream of.

I am at stand still when it come to how the measure the diodes in the waffle board and if that is possible if it is still attached to the board.

Did I say that I have a car to test everything in... And a good working car.
However for the time being I have not taken that one working apart yet. I have a spare with 50% SoC next to it.

Thank you so much in advance.
By now I would also really like to know where I find a MUT(3?) for the car here in DK?
I have an OBD2 LX dongle from Scantool (for canIon)
And how you get to these code:
Chocolate and wine--that covers most of my basic food groups :lol:

It seems that most OBC failures are either in the AC input section, or in the HV DC Output. On rare occasions the waffle plate will have a fault.

The diode check of the waffle plate helps to decide if repairs should proceed or not. There is no need to replace the easy stuff until this is known.

The custom waffle plate can't be repaired, only replaced, which means finding a good one in a salvage unit (mits or nissan). To replace it requires de-soldering 144 large joints in 2 OBC units, then mounting the plate to the heatsink, adding the power board, then soldering 72 joints while in the housing.

The AC Input section faults might involve the filter capacitors, the ceramic resistors, the black relay, other inline components.

The HV DC Output fault is commonly the snubber capacitors and the MCU fuse.
To make the diode check of the waffle plate:

You will need a voltmeter that has the diode check function. When the test leads are placed across a diode in the forward direction, the voltmeter will display the diode drop voltage required to just turn on the diode, typically 0.3 to 0.7 volts depending upon the type of diode.

When the leads are in the reverse direction, then no voltage will be displayed due to the blocking function of the diode.

If there are other components in the circuit in parallel, then the readings will be corrupted. For this reason the Faston terminals should be removed from the board. Hold the wire in place with one hand while pulling up on the white connector to unlock the Faston tab and remove it. Mark the connectors with a sharpie pen to make it easy later.

Here is a diagram to show where the leads need to be placed to check the diode drops and blocks in the waffle plate. In addition there are some resistors internal to the plate that can be checked with the Resistor function of the voltmeter.

[img=https://i.imgur.com/SBC5zA0.png]Waffle Plate Faston Wiring[/img]
mwahlgreen said:
By now I would also really like to know where I find a MUT(3?) for the car here in DK?
I have an OBD2 LX dongle from Scantool (for canIon)

Hi there
I was looking for an MUT3 for ages until someone mentioned that Lexia/Diagbox (for IOn/C-Zero) will also work with an I-MIEV. So I recently got a clone on AliExpress and luckily I still had an old laptop running Win XP.

Haven’t had the chance to do in-depth testing but so far it works great and seems to be a real low cost (less than $100) alternative to MUT 3.