Two Thinks in Finland

[Zuikkis]

Doh! I mentioned last September that we had unexplained "Ext. Iso Fault" on the first test run, but that it hasn't happened after that.

Now it did it again! First time was last week. It was really cold, -25C, and I was low on charge while at city so I took it to parking garage to charge. Garage had probably +10C. Car charged fine but when I left it immediately lit the red triangle and NicoMeter showed "Ext iso fault" again. Doh. But car drove fine for a few hundred meters until it stopped. Powercycle allowed yet another few hundred meters. This happened a few times. But then mysteriously it started working and I drove 15km to home without stops, and now we have driven over 100km without issues during many days.

But now while at home I noticed from my home automation that Think is not charging while it should be. I went to look and sure enough the red triangle was there again.  But now I was at home with my CHAS laptop ready so I could debug it. This is with charger cable still connected, as I was afraid the error would go away if I remove it.

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Some decoding of the fields:

Errcode 41:
ERR_RM_GATE_DRIVE = 41   //   0x0029

Dins:
din_dcdc_fault_l   Dins[0]^11;
din_key_run_h      dins[0]^12;
din_pilot_wu_h      dins[0]^13;

BMI Flag:
can_bmi_flags[0]^1;   bmi_sys_gener_err
can_bmi_flags[0]^2;   bmi_sys_iso_err
can_bmi_flags[1]^6;   bmi_sys_ext_iso_err


Now, the DCDC fault sounds interesting? Does that mean the 12V battery charger? I assume that is inside the PCU?
Edit: I assume "AiVbatF" is 12V battery voltage? It is only 12.08V... Maybe I'm on a right track.

[Zuikkis]

In order to find the isolation fault, I manufactured a dummy connector that can be plugged into PCU heater and A/C connectors, so I could test if that affects it.

It didn't, still external isolation fault. Perhaps it's moisture inside the PCU?

Then I did something stupid. I powered the car when the heater connector was empty. Obviously all kinds of warning lights came up, so I power off and reinstall the connector.

However now the car is really dead. NikoMeter shows "*crash* *emergency* and not much more. Contactors don't click.

CHAS shows "bmi_sys_emergency" and "bmi_sys_crash" in BMIFlag1.

I have working CommTool also, using the chinese PCAN clone adapter. Also there I can see the emergency/crash, otherwise everything looks normal. I tried to clear the faults with sending ID 61e and 745 as instructed in the Vehicle_CAN_Bus_Guide_V3.0.docx document. Car responds correctly showing that codes are cleared, but it still doesn't work.

I think the codes need to be cleared from the PCU? I tried installing ThinkTechCenter, but it can't connect to the car. I remember seeing some instructions here earlier, I'll try if I can make it work.

Looking at my documents, I found this worrying remark in file PCUReplacementProcedure.pdf:

"Never, ever plug in the low voltage connector to the heater without having the high voltage connector
plugged in to a working high voltage port on the PCU. It will necessitate the VCU and CDCM being
replaced until that mistake is not made again"

    

What are VCU and CDCM anyway, are they inside the PCU?

[Marsto]

Hi Zuikkis. The cdcm is the climate defrost control module and is a black box under the dashboard on the passenger side. It controls the heat and cold air in the car. The VCU is the Vehicle Control Module and controls everything in the car from if you have the right key to dashboard lights and lots more. I think it is located under the dashboard by the steering column on the driver side. Have you tried to clear codes with the clear all malf codes in commtool?

[Zuikkis]

Thanks @Marsto !

I forgot to say, I couldn't get serial port connection working in CommTool, only CAN. Now I see that you have version 3.08, I have some 2.xx installed but I found 3.08 already. I'll soon try again if it works.

Also I think I have now installed Think TechCentre properly.

[worry]

I don't think anything should happen just by trying to start without a HV-plug in the PCU. It should do just the same as if the crash-swith has released or the lid on the PCU is removed. It won't or shouldn't start.

I suspect moisture and corrosion inside PCU. Just as I had in this thread:
https://elbilforum.no/index.php?topic=64383.0

Read what I wrote about measuring the EPO-circuit. Remove the little front lid of the PCU and look inside.

[Zuikkis]

Hmmh. I got Think TechCentre working! There were some unrelated sounding errors in PCU which I managed to clear. They did not reappear. PCU now thinks the car is fine.

But BMS still reports crash and emergency, and those can't be cleared. I wonder what's happened?

Isolation fault is not reported, I'm pretty sure the car would drive. This is now a different issue from the original.

[Zuikkis]

Oh no. It was just a blown fuse.



I tried to think back what exactly I did when the emergency/crash error started. In addition to removing the heater/AC HV wires, I also measured the HV + and - insulation resistance to ground (car powered off obviously!). It was about 5 megaohms whic I think is quite ok? I measured it from the heater connector using regular multimeter.

I can't remember it happening but I must have briefly short circuited the "connector sense" pin to ground. According to schematic, it seems to be permanent 12V..

Anyway, now back to wondering about the isolation error. It is gone now, though, but I'm sure it will come back later. worry's idea of moisture in PCU might be correct. I'll try to open the front lid.

Sucks a bit that I have A/C, makes accessing the PCU much more difficult. A/C doesn't work, though, I maybe remove it permanently if I need to remove the PCU..

[worry]

Great! Glad you found it. 
Keep us posted. :-)

[Marsto]

Great news. Was it the 7.5A fuse in the fusebox that blew?

[Zuikkis]

Great news. Was it the 7.5A fuse in the fusebox that blew?

Yes, exactly that one.

[Marsto]

Thanks alot Zuikkis. You did an exellent job finding out but of course you are also an above average expert. This give me the opportunity to post this video from youtube to other Think owners that don`t have quite as much expertise knowledge in their head. Here is the link from Dala EV repair.

https://www.youtube.com/watch?v=EpKY4OT5c24

[Warlock]

 

Nice to see you found the error your self, and so quickly Zuikkis
And yeah you are right that turning off the car will remove the fault from CHAS.
The "interesting" part, as you say, is the DCDC converter, was this before the fuse blew?
I'm not sure what this exactly points to, do you know if the HWDC unit reported anything through CAN?

If the external insulation (ISO) fault disappear when using blind plugs in the PCU, then the fault is in the external equipment you just unplugged (typically the heater)

and yeah...
for the video (and every car troubleshooting), check 12V, check fuses, check CAN-messages.
That order

[Zuikkis]

The DCDC converter error and ISO error were there before this fuse thing. I tried blind plug in both connectors and it did not fix the isolation error. This suggests that it must be in PCU or drive motor? Perhaps even in battery.

I think perhaps the DCDC error is a red herring. Perhaps DCDC fails simply because there is no HV available because of the isolation error?

Then again, the isolation error seems to come very easily when charging. Last weekend the car was like, it could easily be driven for several kilometers and the error would not come. But plug in charger and isolation error pops up in a few seconds.

Then again, a week ago it failed during driving with the same isolation error, so it's not only the charger that causes it.

And obviously now it fixed itself while I was wondering this blown fuse issue. Drives and charges well. But I can't trust it enough.

Most logical explanation would be water in the PCU, as worry suggested. I'll try to remove the cover to check how it looks inside.

[Zuikkis]

Thanks alot Zuikkis. You did an exellent job finding out but of course you are also an above average expert. This give me the opportunity to post this video from youtube to other Think owners that don`t have quite as much expertise knowledge in their head. Here is the link from Dala EV repair.

Heh, funny that he took exactly the same steps as me, exactly the same schematic pages shown that I just pasted above and exactly the same fuse that was the culprit. I didn't know we have fellow Think fixers in Finland.

And horrors that some car repair had actually replaced the ABS pump when trying to find the problem!

My PCU also showed ABS fault code with Think TechCentre, even though ABS light was not lit and ABS is working. I think the PCU remembers old codes? I did have ABS issues months ago but it fixed itself.. Now that I cleared ABS code it hasn't come back.

[Zuikkis]

The DCDC fault is a red herring. I looked at other CHAS screenshots from other people, especially in this thread:

https://elbilforum.no/index.php?topic=64367.0

Many screenshots here have this set:
din_dcdc_fault_l   Dins[0]^11;

So I think it's as I thought; if there is any failure that prevents HV contactors operating, it will also pop up this DCDC fault...