I just checked all voltages from inside the MCM (was very careful to not make any shorts) and they are all good. I guess all options are exhausted now, so I will order new MCM.

 

I got the MCM replacement today, installed it in the car and it's working! Went to do the vehicle inspection since it expired in the meantime and it passed without problems. Thank you very much for all your tips and advice, wouldn't be able to solve it without your help!

However, when I was driving back home, the engine light got on again and I checked with the scanner and got P0404. I'm not sure, if this is realted to what I was doing in the last two months at all. I just deleted the code for now and will see, if it returns sometime.


Two questions poped up in my head now:
a) Is IMA firmware installed on the MCM or somewhere else? I mean the software that received that update which then uses the battery in a more conservative way.
b) How often do you suggest that I balance the IMA battery and should I do the full 3 cycles with deep discharging (like I did the last time) every time? I would like to keep the battery in the best shape possible.

 

P0404 is "EGR valve insufficient lift detected" - if it clears and stays away for long periods, I wouldn't worry about it. There are some electrical connector checks, but if the light stays out most of the time, it's probably just a failing EGR valve.

a) MCM. The software to which you're referring is only applicable to 2006+ HCH. There was no "conservative" update to the 03-05. The "update" to the 03-05 was to eliminate the PTC circuit.
b) overnight charge (8-12 hr) only 2-4 times per year. ONE of those charges should include the prior full charge criteria, and ONE discharge to 96V once per year followed by another topping charge.

 

I have the same issue as him above but I haven’t done all the testing of cells. But how do I tell what McM is updated or not? And where is the wire you have to cut?

 

The only difference is I have codes P1600, P1449, P0420

 

P1600 General IMA fault.
P1449 is likely severe battery cell failure, though it can indicate a temperature issue
P0420 is bad cat.

 

so I had the 1449 code then bought a battery not new. And threw it in and same code. But the 1600 code what could that be? Could it be mcm?

 

To get rid of the P1449 code, you need to replace it with a known good battery.

Did you do that?

 

im gonna go with no it’s not known to be good. Idk how to test for that. Should I just buy a new one for 1200? Or a reman for 1000?

 

It's about $ for warranty period and selecting a reputable builder with longevity and a good reputation.

Before you spend any more $, I'd blink the codes:

https://99mpg.com/mikestips/readingtheblinkcod/

The codes aren't identical between the insight and the HCH1, but the process is the same. This will help you isolate if the P1449 is related to cell failure or a temperature issue.