Have seen several cars recently with that issue, the fuse has small conductors that do not tolerate much over current.
Easiest way to do that is to measure the Volts in the main HV wires coming out of the battery top terminals
With the car idling, this voltage should be a stable 140-160V, and reving the engine should not change it much. If the fuse is blown, the voltage will swing over a 100-240V range when the engine rpm is changed.
Good luck with your troubleshooting.
thanks for the idea about the fuse, this does sound more like a fuse issue since the suddenness of the problem. Question though, the IMA does occasional start the engine, could it do that if this fuse was blown?
Thought I would bring this story to a conclusion. After some self diagnosis it appeared likely that the problem was the commutation sensor itself. Considering the difficulty of replacing those (beyond my mechanical abilities) I took it to our local Honda dealer. I told them what I knew, but was very curious to see what they thought it was. Later that day the guy called and said they had diagnosed the problem down to a bad commutation sensor and a bad MCM. I told him that I didn't see how both could fail at the same time and I doubted very much that there was any problem with the MCM. He just said that was what their diagnostics were showing. So I gave him the go ahead to replace the sensor only and not the MCM. Next day he called me and said replacing the sensor only worked and everything was running fine!
When I picked up the car he gave me the replaced part and I see one of the three sensors has an abrasion on its back side, so the rubber was worn off and a small hole had developed. Not sure if this happened during the downshift or the downshift was just the last straw of an already dying sensor.
I'm not really upset at the dealer, considering they don't see many issues like this, they probably replace the MCM as standard procedure in these situations. At least they diagnosed the sensor problem correctly and fixed it properly. I'm happy I knew enough to save myself some money, largely because of this forum and the people on it that are so eager to help!
Glad to see the problem solved. You have a first for that problem.
Also impressed that they gave you the part.
This is something everyone should do, Request the old part that was replaced. It is your right. (Unless it is a warranty item)
Now the challenge is to figure out why that part broke.
01 MT "Little Red Rocket"
The first "TURBOCHARGED" Hybrid, Insight G1- (01/2003)
MaxIMA Battery (Serial #2), on 8/25/12 @ 301,520 miles
Use: 320,000 mi. @ 57.8 LMPG
Thanks for that update. It fits in well with my experience of sensors with the ends worn through. Clearly there is not much clearance between the commutation plate and the sensors !!! The missed shift or whatever it was must have just caused sufficient contact to finish it off. The only other explanation is the sensor mounting bolt came loose and it gradually crept out of it's location and made contact with the plate.
Please post a pic of your sensors for comparison.
OBDIIC&C $50 inc software, pcb, switch and obdii plug.
IMAC&C HCH1 $50 inc software and pcb.
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