Didn't have time yesterday, so here are the results from today:

1) All readings from BCM connector are there.
2) I opened up MCM, but couldn't spot anything unusual. Everything looks like new.
3) I checked the resistance of those two fuses and both are ~1,6 (that's also what I get, if I put both probes together).
4) Resistance of the PTC circuit is 20,6.
5) I checked for voltage between PTC circuit and sticks on both sides of the pack and there was none.
6) I visually checked both sides of the pack and also checked for continuity on different wires on the junction board, but didn't find anything unusual.

7) I tried to get the "blink" codes, but I didn't succeed. When the car was running (should it be, or should be in some other state?) and the engine and IMA lights were on, I put a paper clip in those two slots, but nothing happened. I tried a few different times from a different angles and depth. I use that clip to short my PC supply sometimes (to turn it on), so it should work fine. Is there maybe some other slots you have to short on Civic? I didn't want to experiment to not break something.


I also noticed that when I turn the key in ON position, IMA relay is closed and the battery voltage (around 160V now) can be read on the terminals. But when I turn the key to final position to start the engine relay can be heard again and the battery is turned off, so the the car has to use normal starter.

I also read codes with OBD reader at the end, and now it is P1600 and P1570, so I think we can conclude that the latter is now persistent.

 

Car off
Short the pins
Turn key to ON (not start)
Read blinks

All symptoms and diagnostics thus far point to MCM failure or it needing to be "updated".

 

Nothing. I tried two times (put the pin out and in) and waited around 20s after turning the key to ON.

Can I somehow check with multimeter that the short is actually working?

 

Unknown. Perhaps non-U.S. spec vehicles function differently? I have an '03 HCH, and this works for me.

IMHO, you have two options:

1) Take it to someone for enhanced diagnostics (professional grade code reader).
2) Replace MCM

 

Just to confirm that I'm doing the right slots. In my Civic the shorter edge of the OBD port is on the top, so I put the pin in the far right slot and on the bottom (longer edge) I put it to the 4th from the right. Do you do the same in your car?


EDIT: I see here it says short the pins 4 and 9 (https://honda-tech.com/forums/honda-...anner-2900091/), but no idea which ones would that be?

 

that sounds correct.

 

Okay thanks, I was doing the correct ones. I will try a few more times tomorrow, otherwise I will just order a replacement MCM. Found a nice deal on ebay that accepts returns.


EDIT: I found a service bulletin for IMA batteries here: https://static.nhtsa.gov/odi/tsbs/20...40484-6697.pdf
Would I run into a problem, if I replace my MCM with another one? The bulletin says that the software needs to match the battery.

 

Yes, but I discussed that already in post #21. You will need to cut the PTC wire. P1569 is the PTC circuit code.

This isn't the SB in question, but they point out where it "may" be cut:

https://static.nhtsa.gov/odi/tsbs/20...45879-6420.pdf

EDIT: It IS the that discusses removal of the PTC strips

 

Oh I see. So that "software matching to battery" is actually meaning that the MCM is aware, if PTC strips are there or not, which you can also fix hardware-wise?

I inspected my OBD2 port now and found out that only
4 5 7
14 16
are occupied, so there can't be any short between 4 and 9 (because 9 is blank)?


I was also searching around a bit yesterday and found out that I can buy Honda HDS HIM device which would allow me to configure stuff like a dealer can. Would I be able to fix the MCM that way? I find it kinda hard to believe that MCM would just break hardware wise, if it was working a few weeks ago before I took out the battery again. The price for HIM is kinda the same as I would pay for "new" MDM.

 

Old MCM needs the PTC strips intact OR a 20-30Ω resistor spoofing the MCM.
New MCM needs for NO PTC strips to be present. Cut the wire or detach and tape-off the cable

You're talking about getting a pirated copy of HDS, which can be virus laden, and needing access to Honda updates (no idea how) vs. swapping out a part.

It wasn't working a few weeks ago. You had a persistent P1570 as your tap voltages were good. It just had more function than you do now.

The only way I can see it's not the MCM is if the pins aren't making contact between the orange connector and the MCM socket.