That fix is definitely far out! Whatever possessed you to try/do that? I will give it a try...nothing to lose. If it works for me, then you need to apply for a patent. I may have to take a drive since we don't have many long hills here where I live. Maybe I will just try it on a level four lane with low traffic (in case the unexpected happens).

I was reading another post that talked about the switch (es) on the clutch pedal that fail and cause charging problems. And so I took the shield off under the dash and used my finger to work the switches (there are two, one that is depressed when the clutch pedal is out and another that gets depressed when you push in the clutch (also letting the other switch plunger come out) . So after "fiddling" with them including pulling the connector off, I decided to start the car. Was I surprised when the IMA motor/alternator/generator started the car (not the 12V starter) and the charge gauge showed about one fourth charging at idle and the battery got up to 2 bars charge. Well, I could not let it sit there and charge the IMA battery figuring driving it would increase the charging. Backed out of the driveway and started down the street and suddenly the charging stopped (but the 2 bars remained). Crap Drove back to the driveway and tried more fiddling with the switches. Nothing. However, now if I continue to repeatedly start the engine (using the 12V starter since the other "starter" does nothing) I can get a fleeting charging indication that quickly disappears. Slowly my 2 bars have disappeared. I also pulled both swithes and used an VOM to test for continuity when the switch is depressed and none when the plunger is out. Both appeared to work ok, but they are strange switches (cost $60 from the local Honda dealer and $45 with shipping from Majestic). Anyone know how these work and why so much for an on/off switch? Also, experimenting by disconnected showed one controlled starting the car (car would not start when disconnected) and the other did not appear to affect anything.

Went to Advance Auto and used the code reader again. Same codes (1600, 1575). This time I reviewed the stored frame data. Both frames showed nothing unexpected (0 mph, 180 degree temp, etc and 850 rpm's even though my tach on the car is reading 950-1000). Is there some minimum rpm that must be maintained to get enough charge out of the IMA motor/alternator/generator so the 12V light does not come on. It appears my tach is 150 or so off (too high reading) and maybe I need to up the idle? Anyone know where the adjustment is?

Did not shut the car off and drove around several miles with no engine light/IMA light on (12V still came on and no indication of IMA battery charging). Thought I might have lucked out. Drove in the driveway, turned off the car and then restarted. Guess what, IMA light and check eng light on

One positive is the AC seems to be working now, even when idling in the driveway. Go figure. As I said before the hybrids have too many failure points. At least I know the compressor works and the charge is ok.

Back to the fix you described. It brought back an old memory. I can remember driving to the post office with my mother in a 52 *****'s jeep and she would get to the top of a long hill and put it in neutral, shut the engine off and coast almost all the way. Now that was truly gas saving/green, without the high tech we are experiencing today. Albeit, gas was probably 2 cents a gallon back then, but at least less pollution was generated.

Sorry for such a long post...got carried away.

 

Isn't there some sort of re-learn procedure they sometimes do to charge up the IMA battery (since you say you can sometimes get a couple of bars on it now), where you rev it at something like 3000 or 3500 rpm until it charges all the way up?
You might want to try that.

The 1600 code is like a "placeholder"; it doesn't relate to anything in particular.
The service manual says something other than what Autozone says regarding the P1575 code; I think we talked about the P1575 in another thread somewhere here.

 

Yes, I remember reading about the 3500 rpm process too. Trouble is I have been unable since that very first time to get an IMA battery charge indication that lasts longer tha a second or two (also intermittent) when I start the car. My two bars have also disappeared.

I am wondering if the luck I had before had nothing to do with the clutch switches, but were the result of installing a fully charged 12V battery. Is it possible that overnight a slow feedback charge went from the 12V backt hrough the DC-to-DC converter and put some charge in the 144V? This may have been enough (couple of bars) to start the engine and prevent whatever is shutting down the charging upon start up. Why it stopped charging when I tried driving is, in this scenario, a mystery. I did a full charge again on the 12V last night and we will see what happens today.

I have been tempted to charge the 12V fully disconnected from the vehicle and then reconnect and hook my 12V charger (6 amp max output) up and see if charging occurs reasonably (couple of amps) from the charger. Problem is I have also read that charging with the 12V connected can damage the electronics. (not sure what people do when they have to jump the car from another car. Is that so short of an event that no damage occurs or perhaps the good car only puts out a small amperage?)

This has been an interesting journey. I hope I end up finding a pot of gold or the wizard at the end.

 

When I started the car after it sat for 3 months (it started with the IMA motor) and took it for a ride I didn't notice something was wrong until I got to the first stop sign and saw the 12V icon light. Then I noticed I had no assist/charge. I immediately got the car back home, shut it off and sure enough when I tried to start it again it was completely dead.

I put the charger on overnight with both battery cables disconnected so the charger was just on the battery. The next morning the car started with the 12V/starter and I would get 2-3 bars of charge for a couple seconds then I would hear a relay pick and the charge would stop and the CEL/IMA/12V icon would light. At this point I thought the car was finally done but I figured there was a full charge on the 12V so I should be safe to take it for a drive and see if it would fix itself. I don't know why I turned it off/on and popped the clutch. It just kind of popped into my head. I got lucky is all.

I should add my codes are P1600 and P1449 (battery overheating/deterioration/deviation between cells) and I've never had the P1575 so you probably have something else going on. I think you need a definitive answer on what exactly the Honda specific P1575 is.

Best of luck...

 

Well I tried the turning the key off in 5th gear with the clutch in, waited a few seconds and turned on the key. Engine started, but still no indication of IMA battery charging or charge in IMA battery. Tried it several more times in different gears, with the clutch in and out when I turned off the key. Still no go. Everything is the same as it was. Drats.

The full charge on the 12V and waiting overnight to see if a charge trickled back to the 144V theory did not prove out either.

Looks like it is time to pull the back seat and begin checking connections. Given the one time longer charging event and intermittent very short duration charge indication thereafter seems to say the 100 amp fuze on the junctions board (previous 1575 hint from service manual) is ok. Other manufacturers seems to use the 1575 code for brake pedal switches and engine mount solonoids (Audi). I guess it must be a manufacturer's choice rather than standard. The Adv Auto tester seemed to be indicating something to do with engine speed/idle fault.

Anyone know an easy way to test a relay for good operation (aside from applying power and listening for movement of the contacts/relay pulling in or hooking a VOM up to the switched connectors while applying power to the other connectors (which is which in terms of connectors?)? Hopefully they are all 12V on the car.

Thanks to all of you for your suggestions. So many ways these things can fail.

 

Did you actually pop the clutch or use the key to restart the car? If the key switch has 4 positions, Off/Acc/On/Start, then what I did was with the clutch depressed turned the switch to Off, waited, turned the key to On, waited, then popped the clutch. I didn't restart the car by switching to the Start position.

Also might it not be worthwhile to bite the bullet and bring the car to a Honda dealer and pay the diagnostic fee just to verify what the actual failed component is? You could still maybe purchase and install the part(s) yourself.

Just a thought.

 

I actually popped the clutch without going to start, but I also tried it by just turning the key off, waiting a few seconds and then turning the key back on (not to 12V start). Nothing seemed to work to fix the charging problem. I was a little worried doing it, half expecting every light on the dash to stay on, but it does not seem to have harmed anything.

Your suggestion of going to the Honda dealer is going to be my last step (if I take it rather than just drive the car without the IMA and turn up the idle). I figure I should check for loose connections, etc. behind the back seat first (still looking for a set of high voltage electrician gloves!). I don't have much faith in the Honda dealer to say anything other than I need a new IMA battery or MCM/BCM or something else ridiculously expensive.

 

Just to close out part of my saga. I finally replaced the 100 amp fuse on the 144v battery and the car now charges/assists/autostops/etc. Currently getting a P1600 and P1449 codes using a reader. Using the Blinking Light Code technique described on the Insight forum I know the P1449 subcode is "78" which is Battery Module Deterioration (8 plus years old and out of balance in the cells/cell sticks resulting in lower capacity).

 

Ok sorry I'm so late here. Yes, I have some ideas:

Check your fuse. I believe #16 under the dash, check your manual for the IMA fuse. Hook up a voltmeter and MAKE SURE it has power.

I was screwing around with the electrical, using the one next to the IMA fuse to power a radar detector when I accidentally tapped the frame of the car with the lead line. Had the same exact problems you described. IMA totally dead visibly. $800 later had a new fuse circuit board. I had fried not only fuse block 15 but 16 as well, the IMA. Of course the fuses looked fine to me, but at the time I had no voltmeter. Luckily when I told the tech I was screwing around with fuse 15, he quickly diagnosed the problem that I had shorted the fuse block, not the fuse.

It is my hypothesis that when you changed your battery, a power surge might have occurred that disrupted either fuse 16 or the block itself. Lack of power to the IMA will result in the exact problems you are describing. Although some of your descriptions are slightly different than what happened to me, I would check all of your IMA fuses, even the ones under the hood, and check the volts across it as well. Should point you in the right path. If any of those have no/low volts, your problem is electrical and nothing to do with the IMA system.

On another note, I feel bad I didn't see this thread earlier. When I read the initial guy who started this thread's problem, I immediately thought it was the computer. Could have saved him a lot of headache. Sorry bud.

 

Well it seems we have all had some luck in fixing at least part of our problems, albeit different problems. These hybrids can fail in so many ways and are probably best left to people who trade up every few years or the diehard problem solvers. I wish Honda had designed the car to default to the 1.3L ICE and standard 12V charging when anything goes wrong with the IMA system. I guess it does until the 144V battery gets bad enough/fails in a way to prevent 12V charging. If only someone would build/sell a bolt-on IMA high voltage to 12V DC-DC converter or alternator system and ECU that could keep the IMA/CEL "hybrid" codes from occurring...downshifting is the assist.