Well...here is the latest.

I was finally able to get back to the garage today. Removed the battery, cut the red wire and reinstalled.

The code indeed changed, but to P1569, Battery Cell Temperature Signal Circuit Problem. Pretty obvious where that code is coming from!

For fun I swapped back to the original (which was in the car and supposedly received an update from the Honda dealer after I replaced the battery...) and it provided the P1569 as well along with P1580 (same as before.)

A little stuck now trying to figure out the next move. I could reconnect the temp wire and I am sure I would go back to one MCM at P1637 and the other at P1580.

Wondering if I should go to Honda with the P1569 MCM and ask for an update to ignore the missing temp signal.

 

They will do it, but they'll charge you.

 

I know. Not sure if I have other options. I could pick up another MCM, but not sure that would change the situation.

 

Success!

I called around locally and found and independent shop that has the Honda computer. Shout out to GT Imports in Clemmons, NC. They listened carefully and were willing to take the time to get the right software into the MCM. I was skeptical as they noted that I would need to restore the heat sensor circuit and reset the MCM to clear that code in order to get the check lights off, but sure enough, after splicing the wires back in place and resetting the MCM full function was restored and no lights.

I realize I am still on borrowed time with this battery, but for now I should be able to get through inspection and drive it for a while. I figure I will use it for my daily commute (about 60 miles,) instead of my truck, the difference between 14 and 40 mpg should have the car paying me back over the course of the year.

Thanks for you help in the process, could not have done it without the input of others who have traveled this path ahead of me.

 

Glad you got it sorted out! If you keep the speed closer to 65-68 and it's not too hilly, you'll find yourself pushing mid to high 40s if you don't have too many recalibrations.

The HCH1 has been reported to get into the 50s with just some mild effort.