12V System Charging System Problem

I hate to display my ignorance, but what is "maintenance mode" on the Clarity? I can't find any reference to it in the Manual.
 
vicw said:
I hate to display my ignorance, but what is "maintenance mode" on the Clarity? I can't find any reference to it in the Manual.
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Maintenance mode allows one to start the car with the ICE motor running continuously for diagnostic purposes or to warm the engine to change oil and perhaps other reasons.

ClarityHotStart.webp
 
Thomas Mitchell said:
I found it in another thread. Can't recall if it was here, or ClarityForums.
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FWIW, I found what seems to be the initial reference to the procedure in a post #23, by jeff628, in the thread "Oil Change Frequency for Clarity", There wasn't any source given in that post either, but apparently it works, and you were able to use it.

Good info to have, but I would definitely not be able to do it without reading along.
 
Thomas Mitchell said:
Maintenance mode allows one to start the car with the ICE motor running continuously for diagnostic purposes or to warm the engine to change oil and perhaps other reasons.

View attachment 15027
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Actually after step 5 (shift to P and press the pedal twice) Maintenance Mode appears on the screen, but the engine will not run until you do step 6 (press brake and push the power button) that's when the engine will start.

Also after step 4 (shift to N and press the pedal twice) a message will appear "Gear Position is N, Release Accelerator Pedal". You can ignore this message.

Also it is advised to not try and drive in maintenance mode. Why I don't know, I read that for the Prius Prime which uses the exact same sequence it said that you could fry your inverter. I don't know if that is true for the Prime or for the Clarity but probably best to not experiment and find out.
 
Good added details. You mentioned that it is advised to not try and drive in Maintenance Mode. That implies that there may be a known source for these instructions. Do you know where they were derived from?
 
vicw said:
Good added details. You mentioned that it is advised to not try and drive in Maintenance Mode. That implies that there may be a known source for these instructions. Do you know where they were derived from?
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No, like Thomas Mitchell said they are just sort of bouncing around on various sites, you will see this if you do a Google search, as it seems to be the standard procedure for all Honda and Toyota hybrids. Not all of them warn about not driving in maintenance mode, but I know I have seen that on some of them. I'm guessing there is an official version on the Honda Service Express website but that is a paid site. The one day cost is not so bad, some people have paid for one day and downloaded as much as they could.
 
I used this maintenance mode once (I think it was the 1st oil change). But honestly, it just seems easier to go for a short drive in HV mode if the goal is to warm up the engine. By the time you locate this procedure (impossible to remember) and execute it properly, you can drive around the block 3 times !
 
Frankwell said:
No, like Thomas Mitchell said they are just sort of bouncing around on various sites, you will see this if you do a Google search, as it seems to be the standard procedure for all Honda and Toyota hybrids. Not all of them warn about not driving in maintenance mode, but I know I have seen that on some of them. I'm guessing there is an official version on the Honda Service Express website but that is a paid site. The one day cost is not so bad, some people have paid for one day and downloaded as much as they could.
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Yes, notes on maintenance mode are in the Honda maintenance manual.

Here are the warnings/notes it provides:
  • "Maintenance Mode" is displayed in the MID.
  • If the engine coolant temperature gets too hot, the engine may not start until the engine coolant temperature drops.
  • To turn the engine OFF and cancel the maintenance mode, turn the vehicle to the OFF (LOCK) mode.
  • The VSA operates normally while the maintenance mode is in operation.
  • During cold starts in maintenance mode, for about 60 seconds there may be some additional transmission noise, this is considered normal.
  • When starting the engine in maintenance mode, you may hear a groan/rattle for about the first minute, or when the engine decelerates. This noise is caused by gear tolerance's, when the generator is not under load. This noise is considered normal while in maintenance mode.

Prior to checking oil level, it states:

Park the vehicle on level ground and enter the maintenance mode, then start the engine. Hold the engine speed at 3,000 rpm with no load (in P or N) until the radiator fan comes on, then turn off the engine, and wait more than 3 minutes
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It's a little bit inconsistent about the wait before checking the oil level. Sometimes it says to let it cool 3 min, other times not.

(It's confusing... the user manual says that the engine can be cold when checking the oil, but the service manual procedure is to always check it warm. It probably doesn't matter much.)
 
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Thomas Mitchell said:
I was told it is a new battery, not a refurb.
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I’d image Honda has a stash of new batteries from the assembly line. It’s much easier to send out a complete unit than to hobble together another pack. It would be interesting to know what becomes of the defective batteries. It could be a single bad cell or just a faulty connection. If I had to guess, I’d say that Honda just sells them off to a salvage operation.

We’re now 4+ years since the car was available for sale and the battery technology is essentially 10 years old. It will be interesting to see what replacement battery will be provided under warranty 5 years from now.
 
So it says they diagnosed that the DC-DC converter was bad, and the technician apparently read on the HondaTech forum that they should replace the entire IPU. In Honda terminology the IPU is the Intelligent Power Unit, which consists of the battery and one or more other associated parts. From what I read in some online documents the Clarity IPU seems to consist of the battery and the DC-DC converter (the Honda Fit IPU also includes the inverter). In theory probably just the DC-DC converter could be replaced, but it appears that at least in the tech forum they instruct to replace the entire IPU even if just the DC-DC converter is bad. Maybe this will be the normal procedure for service at Honda dealers when the DC-DC converter is bad. However I'm wondering if after the battery warranty has expired, maybe there will be non-Honda shops that specialize in EV's and hybrids that will be able to replace just the DC to DC converter. List price for the Clarity PHEV DC-DC converter is $1,374 (on sale at HondaAutomotiveParts.com for $923). And then of course labor which includes pulling out the entire IPU from the car, but I think I read an account somewhere that said that removing the battery isn't a huge deal. Not trivial, but it is apparently fairly accessible.

I'm guessing there will eventually be refurbished Clarity batteries available at some point, and that would be another option when the DC-DC converter goes bad past warranty.
 
I recently came across another Clarity HV battery failure report on FB. The owner said the Clarity stopped dead in it's tracks. These reports always concern me, but I have to say "I really like our Clarity". The mustang Mach E also had a report of the same concern by an owner. Part of the " Power by an electric motor/battery combination" that present new customer concerns. The Mach E was reported as shifting into park and breaking the parking pawl when this happens. Time will tell, and this forum will tell the story. Thanks to all. Enjoy the drive.
 
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