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Re: Help with problems with the 12 v battery

Posted: Wed Jul 01, 2020 7:16 am
by Don
JoeS wrote:Anyone have any more suggestions for Casper?

How old is the 12 volt battery? iMiEV's are notorious for all sorts of problems associated with weak 12 volt batteries, as that battery runs every computer in the car. If the battery is more than 3 or 4 years old, swapping it for a new one would be my very first troubleshooting check, especially now that you know for sure your DC to DC converter is charging it properly


Re: Help with problems with the 12 v battery

Posted: Wed Jul 01, 2020 10:00 am
by kiev
smueller99au wrote:...
So, does anyone have any idea where I would find the connector between the OBC and the battery, and secondly where should I look on the circuit board for some kind of regulator circuit?

Many thanks for the help!!

Copenhagen area, Denmark.

The 12V line connector to the battery is located directly on the "back" of the OBC, i.e. toward the front of the car. It is a black connector with a single blade terminal that is hard-mounted with a steel bracket to the OBC housing. i think it has a large gage white wire.

This is a picture of the connector disassembled, it was quite difficult to extract the terminal.


Re: Help with problems with the 12 v battery

Posted: Wed Jul 01, 2020 10:50 am
by smueller99au
Hi Don.
Thanks for the reply. As I mentioned the battery is pretty new, as in within 6 months. I’ll go check if it has a date stamp on it to confirm though.

What I’m worried about is that the charger drives 14.8V!! This is why it’s shutting down. I managed to get it to drive today at 14.6 volts all the way home. But this morning it didn’t even think about charging. I never saw about 12.8V on the meter.

Are you sure it’s 12v battery related?

@kiev: thanks for the tip with the connector. I’ll see if there’s some corrosion on it.


Re: Help with problems with the 12 v battery

Posted: Thu Jul 02, 2020 11:02 am
by smueller99au
A little update for you.
Battery is new - Exide Premium EA386 (UK:054TE). I just can't find the date stamp on it.

Found the right connector but haven't had a chance to pull it apart yet. I'll try that on the weekend.

I drove it 6 times today. The first 2 times the charger worked as it should. The 3rd time it failed so I immediately switched off and the on-Ready again. This fixed it. Same thing happened the next 2 times. Each time it failed (battery light actually never went out, then exclamation light comes on a few seconds later) a shut down and restart worked. Odd. But it indicates to me some kind of relay is faulty or storage circuit fault (capacitor?). If I can't find anything outside the OBC then I'll have to open it up and start replacing the blue caps on the 12V side.

Any other ideas?


Re: Help with problems with the 12 v battery

Posted: Mon Aug 03, 2020 12:08 pm
by smueller99au
Further update. Problem is fixed. I went through all the connectors, earth wires, etc. as per the service manual and nothing seemed wrong. Did the diagnostics tests also as per the service manual but it passed everything. So, nothing more to do except replace the entire OBC.

Well, this sorted out the problem. No more error, charging voltage back to 14.4V again. Perfect.

I pulled the cover on the old charger but nothing looked 'smoked' on first visual inspection. Should I start by replacing all the capacitors? Or does someone have an idea where the output voltage is regulated from?


Re: Help with problems with the 12 v battery

Posted: Mon Aug 03, 2020 4:44 pm
by kiev
It's in the bottom side plenum of the OBC; the upper side is the HV battery charrger and the lower plenum is the DC/DC converter used to charge the LV Aux battery. There may be a photo posted in one of the threads here, but not sure exactly where just now.

found it posted by skylogger here:

Re: Help with problems with the 12 v battery

Posted: Fri Aug 14, 2020 12:07 pm
by smueller99au
OK, it seems I jumped the gun here.

DC/DC charger worked fine for two weeks. But it has stopped again now. Odd.

Diagbox reads P0A09 Converter fault from the EV ECU. But it's interesting that there is an older fault P1A44 (leak sensor - earth fault) 20km previous. So, what happened?

The first sign was when I started the car at work it was a little delayed in going to Ready, like maybe 2 seconds more. Unfortunately I already hit the gear stick into D and went for the accelerator before it was completely Ready, giving a delayed take-off. I never do this, but on this day I simply was not thinking properly (brain in auto mode). When I reached the top of the parking ramp the car died. Ready disappeared and I had to switch off, wait for yellow ! to vanish then start again. It was fine getting home.

Next day, in the morning, the battery light came once more indicating no DC/DC charging. I did the old switch off/switch on procedure and it was back fine again all the way to work (6 km I drive). On the return home, same thing happened in the parking lot and at the top of the ramp it went to turtle mode. After a reset it was ok for 5-6 seconds then again turtle mode. It did this 3-4 more times on the way home until eventually I just limped home in turtle mode.

Note, the car charges perfectly. The DC/DC charger also works but shuts down immediately (I can see 14.5V sometimes more for about 1 second).

I read out the OBC diagnostics codes as below, but I cannot reset them for some reason. This makes me believe they are permanent. Codes from the OBC (all status temporary):
02 Charge fault (traction battery disconnected)
13 Communication fault with the electric motor ECU (MCU)
29 Loss of communication with the traction battery ECU

So, what have I been doing for diagnostics?
  • I went for diagram ACA03488 showing the DC/DC charging circuit and followed EVECU P0A09 chart
  • I replaced all relays in the 3 relay boxes at the front of the car. I have a complete spare car so I could change all the interesting ones out. No change.
  • I swapped the 12V battery for my iMiev that works perfectly fine. No change.
  • I have checked all earth connections, all interconnectors, all module connectors. I have not looked specifically for the CAN connectors yet, but that's next.
  • I checked the voltage at EV-ECU C-106 pin 2, OBC E-03 pin 8 and 7, earth at E-03 pin 10, earth on the OBC.
  • I checked the voltage on C-111 pin 116 at READY. This gives 9.5V (my iMiev gives 11.1 as the battery is then charging). This pin is OUTPUT from EV-ECU to OBC.
  • I checked the voltage on C-111 pin 127 at READY. This gives 10.0V for 1 second then 0V (my iMiev gives 10.6 as the battery is charging). This pin is OUTPUT from OBC to EV-ECU.
  • When I link C-111 pin 127 and pin 116 together the battery light goes out so the EV-ECU seems to be doing the correct thing. This points to the OBC stopping the charging process.
One more piece of information - the AC compressor was loose before all of this happened so i strapped it down with strip ties, with rubber between the metal. I need to remember to check this tomorrow - maybe there is something wrong here causing the faults. Odd, but weirder things have happened.

Why does the DC/DC charger stop? This is what I need to determine. CAN-bus between OBC and MCU/BMU? I have an OBDLinkLX and the Peugeot ACTIA cable. Is there a way to capture all CAN data to see what is talking to what on the bus? Maybe I can see some faults in there, or corruption? There are no diag codes to indicate faults so far, and I can communicate to the OBC via Diagbox.

Maybe the replacement charger has some loose wires in it.... :-/

Any ideas would be greatly appreciated. Really... I have tried nearly everything I have so far.


Re: Help with problems with the 12 v battery

Posted: Fri Aug 14, 2020 1:23 pm
by kiev
i doubt that you could have the same problem in the OBC, after switching out the OBC. Did you check the fuses on the DC/DC board?

Most likely there is an issue with:

12V aux battery is too low, old, weak or worn out. When you read less than 12V on those test circuits, then your aux is not up to a sufficient level, e.g. 9.5 - 10.6, these are too low and not normal. Maybe the car will run, but it may cause issues too. Either pull the necessary maintenance or buy a new aux and keep on top of it. A fully charged and function aux battery is a critical item in these cars.

The EV-ECU may have a fault.

Not sure what would happen when you short wires together, that is not something i would recommend unless you hae a schematic and absolutely know the circuit function.

Re: Help with problems with the 12 v battery

Posted: Fri Aug 14, 2020 9:49 pm
by smueller99au
Thanks for your response Kiev.

I checked the one fuse I could see on the DC/DC board before installation. I also checked the connectors and resealed the covers. I hope nothing has come loose, but I had better remove the module again and check.

Battery is brand new. I have mentioned this before but couldn’t confirm it at the time. Now I can. The previous owner replaced it 2 months back. I have also charged it fully and performed a load test on it as per the Mitsubishi guide. No problems here. But I agree the voltage at the EVECU seems low. But it is on both cars when I stop the dc/dc charger on the good one.

The shooting of the two wires is described in the Mitsubishi manual. The 116 wire is sending a 12v signal to the charger to start the dc/dc charger and the 127 line is a response from the charger to say it’s all good. There is no problem giving the direct feedback.
This also indicates that the EVECU is performing correctly because it’s the response (127) that is failing after 1 second and not the request (116). My next step may be to interrupt the 116 line and switch it manually a few seconds after ready to ensure correct traction battery voltage.

Note that the same occurs when plugged in to an AC socket. The AC/DC charger works fine, pulling in the necessary relays, but the DC/DC charger operates for only 1 second.

Never mind. I’ll progress with checking the AC (I still don’t believe it’s that) and the CAN bus (Comms to BMS and MCU). And then it’s pull the obc again and check inside.

Cheers anyway

Re: Help with problems with the 12 v battery

Posted: Sat Aug 15, 2020 8:34 am
by kiev
Sorry to be of no help to you. This is the first time to see such an issue and the DC/DC circuit board has not been traced out yet.

Looking at the OBC codes you pulled [02,13,29] in the FSM:

02 Load Connection Abnormal (main battery not connected)
Check Conditions
The on board chargger control power supply voltage is more than 8 V. [should be 5V]
While the on board chargger is allowed to be charged from the EV-ECU.

Judgement Criterion
The output (terminal) voltage is less than 184 V.

13 EV-ECU lost
Check Condition
5 seconds elapsed after the on board chargger control power supply voltage was more than 10 V and less than 16 V.

Judgement Criterion
For more than 3 seconds, the CAN communication data cannot be received from the EV-ECU.

29 Pilot Signal Abnormal
Check Conditions
The on board chargger control power supply voltage is more than 8 V.
While the on board chargger is allowed to be charged from the EV-ECU.
While the AC power supply is being input.

Judgement Criterion
The pilot signal duty ratio is less than 7 % for more than 2 seconds.
The pilot signal duty ratio is more than 97 % for more than 2 seconds.

i went to the symptoms chart to see if there may be some clues there and found that inspection procedure #2 in the symptoms chart has a wealth of connector information that i haven't seen before
[ ]

i see several references to the voltage being too high, and in previous posts you mentioned reading 14.8 for the aux. Unless it was really cold out, that is an abnormally high charging voltage for lead acid battery. Whatever regulates that to 14.4 may be defective, i just don't know where that is located in the system.

i suppose you checked the fusible link on the positive terminal of the aux battery, and any other fuses/links on that terminal?

After reading thru the FSM i'm gonna guess that something in the EV-ECU is not regulating properly; it allows that aux voltage to raise above the limits and this causes the OBC internal LV supply to exceed 8V [should be 5V], which throws the DTCs and shuts down the DC/DC.

Also you said it charges okay from the mains AC, so at least the HV half of the OBC is not affected, so the 02 and 29 codes are inaccurate. Leaving 13 which points to the EV-ECU.

There are several 12V inputs into the OBC control board thru connector E-03, one 12V is hot all the time on pin 7, another is controlled by the EV-ECU CHGB pin and sent thru the A-06X relay to pin 2, another controlled by the EV-ECU CTL pin thru relay A-08X to pin 8, and there is the 12V control signal lines DCSW and SDW from the EV-ECU on pin 4 and 11.

[diagrams to show most of this here: ... C00ENG.pdf and here ... F00ENG.pdf ]

[Skylogger found different pin numbers on his unit in the OBC trouble thread, but it was for a 2010 car
viewtopic.php?f=23&t=4079&start=80#p36888 ]