Well, at the moment I am feeling quite frustrated and defeated. I didn't realize that in order to use the Honda iHDS, you have to have an expense device in addition to paying a subscription fee. According to the service manual, when you swap out the MCM you have to use the HDS to calibrate the motor strator position. I'm not even sure that replacing the MCM will work, because going through the diagnostic process in the service manual basically just keeps telling me to go through all of the same steps I've already done. I did not get to a step that said to replace the MCM, but I just thought that would be the next logical step to try, even though I still don't have 12V at the #18 pin on the 20P connector.

A different point of interest, when I use my scan tool and go to the Honda OEM Advanced section, the U codes that it shows are ONLY under the PGM-FI and TCM. If you look under the DTC troubleshooting for U1205 in the CVT section of the service manual, it asks if the system also indicates the code for the PGM-FI, and says if so, go to that section to troubleshoot. The PGM-FI DTC troubleshooting for the presence of both U0110 and U1205 is slightly different from the process in the IMA section. They show up under IMA in the regular scan tool DTCs (as well as under PGM-FI and TCM headings).

So unless I can somehow get access to a special Honda device, i'm not sure there's anything else I can do at this point.

 

HDS is both a hardware and software item.

I was under the impression you were getting U0110 and U1205 under the IMA system. Either way, their diagnostics are very similar. Under both trees, there are steps indicating "update MCM" or "substitute known good MCM," i.e., replacement.

 

Yes, it says that if you do have battery voltage at the #18 pin on the 20P connector. I'm not sure why I don't have voltage there when I have it everywhere else on that line and there is continuity there between the BCM and MCM. If I understood the manual correctly, that line is supposed to supply power from the MCM to the BCM, but the testing seems to suggest it should be power going into the MCM from the 12V battery, since you test it while it's disconnected. It makes me wonder if despite the continuity tests checking out good, if there's maybe still a problem within the IPU wiring harness that is causing low voltage there.

Would there be any benefit to doing the FCAN circuit troubleshooting?

 

Quik update: I have the iHDS software and a MongoosePlus Honda J2534 cable and ran the DTC search. My U codes only come up under PGM-FI, possibly due to the fact that the iHDS is unable to communicate with the IMA at this time.

I went to check to see if there was a software update for the BCM I had put it in, and interestingly it did not appear that I could use that BCM, because it only gave options for PH2, CA2, or no label batteries and I have a CA3. So I put my original BCM back in and there was a software update for that, which I did. No change in function at this point. I am now going to install the replacement MCM, and hopefully I won't have the same issue with not being able to get matching software for it. I am not feeling super confident about this MCM, as the eBay seller did not package it well. It did have one layer of bubble wrap around it in the box, but was not packed tightly, and moved around in the box, causing bending of the corners on the heat sink fins. I straightened them out as best I could, so I guess we will see.

 

No change yesterday with the swapped MCM, though I'm not surprised. Partly because of the way it was shipped, but also because I didn't actually get to a step in the tree where it told me to swap it. I started to investigate the FCAN lines more last night and I have continuity on all lines between the BCM and MCM for sure. I also checked the lines from the 20P connector behind the right rear seat to the BCM, and I had continuity on both low signal red lines, but only on 1 of the high signal white lines. I need to investigate this further. It was getting dark so I want to try again this morning and also make sure that I am supposed to have continuity there, although it really seems that I should.

 

All FCAN lines checked out fine today from the 20P white connector behind the right rear seat to the BCM 40P connector. I am wondering if the issue is in the PCM. I wanted to flash it with the iHDS J2534 Rewrite program, but it will only bring up anything for modules that there are updates for. I thought about telling the software that I was putting in a new one and seeing if it would work that way, but I'm not sure that's a good idea.

I did see today that the PCM thinks my battery SOC is at 23 or 24%, even though it's currently at 174.7V. According to iHDS because there is a communication error, this is likely the last reported SOC before failure. I've uploaded the PDF of the data list from iHDS.

 

SoC is calculated based on voltage and current response. Resting voltage doesn't matter.

 

Okay, I see. Here is what it says in the iHDS for further clarification for anyone who may come across this:

SOC
(%)

This parameter displays the battery module state of change (SOC) of the IMA system in percentage.
The system's SOC is computed by the MCM using IMA Battery temperature, voltage, and current, and inputs the information to the ECM/PCM via CAN.
The ECM/PCM controls the quantity of assist or generation to maintain the battery module SOC within a specified range. If the battery module SOC is out of the specified range, the MCM stops the use of the IMA Motor to prevent over-discharge/overcharge.
If a problem occurs with the IMA system, for example low battery module SOC, low temperature, faulty IMA system, etc., the ECM/PCM will use the 12V starter instead of the IMA motor.
When a communication error occurs with the MCM, the latest value normally received before the error is output.

 

Since I've been so far unsuccessful with any of the major changes, I'm going over some of the basics again and I have a couple of questions. Some of the wires on the BCM 40P connector and MCM 20P connector have a small amount of movement when I gently pull on them. Is that normal? Previously I really just checked that the connectors were tight. Second question is about the big plug in the engine compartment. It doesn't feel loose, but does this look normal? It looks like maybe there was something else around it at some point or almost like it's slightly pulled out?

 

When unplugged, the wires in the electronics connectors may have some wiggle, but that should minimize once installed.

Can't really say on that orange connector. Does look a little suspicious. If you want to investigate, disarm the battery and allow the capacitors to discharge, use reasonable protection against high voltage if you can't confirm there is no voltage present.