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Discussion Starter #1
Hello everybody! My name is Sergio, I am new at this forum and I own a Honda Civic Hybrid second gen in Toronto, Canada.

Few days ago, I uploaded a video in YouTube to explain what is my situation with my car. The title of the video is "Honda Civic Hybrid 2008 - 12V Battery dropping" so I hope you can find it easy.

Then, I asked to Peter to see the video and tell me what could happened with the HCH2. Also, I began to see some Peter's videos so I have learned about the CAN bus protocol and the OBDII.

After that, Peter answered me:

"Do you have the Honda workshop manuals?
If not get them and the electrical troubleshooting ones if available .

Anyway looking at the 4 pin connector on the Dc-Dc converter. My manual shows that

Pin 1 is not shown but (may be ground) (You could test this)
Pin 2 is connected to a switched 12v + (Have you done this?)
Pin 3 and 4 are serial data comms signals.

If you connect pin 2 to 12v + does the converter now work?

Your best bet might be to reinstall all the IMA or at least the MCM/BCM and probe the 4 pin signals at the DC-DC plug to find out what they are?
You may well need logic analyser on pins 3-4 to capture the serial data for analysis.

Please post your question and my response on the Honda Insight forum in the other hybrid section.
Others more expert in the HCH2 will then chip in with info.

Helm inc and google are your friend"

So today I will test the DC-DC Converter as Peter told me, to see if it works.

Also, I would like to acquire the OBDII CAN bus testing device or do it by myself, if Peter allows me to do it. But also I figured out that some people actually connect a Raspberry Pi and a PiCAN shield to get a bus data logging. You can connect a Touch Screen or LCD to the Raspberry Pi and programming it via C or Phyton and get your own HMI interface as well.

So, do you guys think it is possible to connect the Raspberry Pi or would be better the Peter's device?

Also, what do you think is happening with the 12V Battery and the DC-DC Converter? Do you know what kind of information is sent by pins 3 and 4?

PD: Thanks to Peter his useful information in this forum. I am actually working around it and I'll keep you guys updated about the progress.

11,800 Posts
I think your dc-dc will probably work once you have it powered up correctly..

There is no pi/raspberry device to connect to an HCH2 canbus, as there is no data in the public domain about what goes on in the Honda CAN bus lines.

My modified CAN bus HCH2 device currently only displays the voltage tap module readings.
It would require hundreds of hours of well funded reverse engineering to develop the device to display more information...

2 Posts
Discussion Starter #4
New updates

Hello everybody. I'm sorry for my inactivity this two weeks, but I was in a trip, now I'm back at home.

Regarding to the DC-DC Converter, I made a couple of experiments taking into account what Peter told me, and I noticed that this device works if you put +12V over the pin 2. It doesn't need any other connection, but it's important to know this:

* The high voltage battery must be installed

* If the DC-DC Converter still has +12V in the pin 2 and 160V in its input when the car is turned off, the device will be "blocked", so the next time you turn on the car, it will not work, even if you have +12V in pin 2 and 160V in the input.

So make sure of this.

So now the electric motor can recharge the 160V battery and the car can work, but the IMA system is still failing, due to the batteries (that I made by myself the last year) are not connected to the sensors (I will upload a YouTube video showing you the new HV battery). Now I'm a little bit worried about this:

- The +12V voltage enable the DC-DC Converter so this divide provides almost +14.5V to the 12V battery, but it doesn't care about the 12V battery's SoC, so I was thinking of put something like a solar charge controller between the output of the DC-DC Converter and the 12V battery, so it could measure the state of the battery and cut off the source if it's charged, otherwise, I think the battery will be broken in a few days. What do you think guys?.

- I realized that the HV Battery voltage drops fast (from 160V to 150 in 10 minutes at 1000 RPM), but the batteries are new. Do you know how much current could flow trough the DC-DC Converter, and how much current does the electric motor can regenerate? or maybe is the current draining in some point?

About S Keith question, I'm looking for both, due to actually I need help to fix the car, but at the same time I would like to share the progress with this community. It could be useful for somebody else.

Soon, I will upload a new YouTube video explaining what I measured and all the things and experiments I did, and for sure, I will share the link with you guys.

PD: Does anybody know how the inverter's pins works? Thank you!

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