Helping a friend with his 2006 HCH2. Car had the engine, IMA, and 12V battery lights all on.

We went ahead and dropped in a new 12V battery and good used IMA battery pack. Engine light and IMA lights went away. However the 12V light is still on, and battery is draining.

Should I replace the DC-DC converter next?
Or do a software update to the ECU?
Or something else?

 

The DC-DC converter sounds like the culprit.

I have two of these, I've replaced both 12V with an oversized 51R and dropped in spare packs. I never needed to do anything with the ECU.

The IMA/CEL lights went out when you disconnected the 12V.

What is the voltage across the battery terminals when idling? It behaves a little differently than a car with an alternator and can show in the 12s when running.

Is the IMA system functioning properly?

I recommend you drive the car until the CEL comes back on. Read the code. I recommend something like this for monitoring voltage while driving:


and one of these + Torque app to read codes:

http://www.newegg.com/Product/Produc...9SIA1EF0FF3686

Good luck,

Steve

 

Measure 12V battery voltage when car is running with headlights turned ON. It should be over 13.5V. If not, charging is not working.

 

swapped DC-DC converter. problem gone! thanks guys!!

 

Glad to hear it's sorted. Thanks for the follow-up.

 

Did you have to do any programming or did you just do a straight swap? I keep reading about having to program the DC to DC converter. No definite answer on this.... I'm thinking there is no programming needed and probably a rumour. Since you didn't mention that you had it programmed, I am going to assume that a straight swap is the fix.

The DC to DC converter is putting out 8 volts. Car dies when disconnecting 12V battery. Hybrid battery won't charge either, and hasn't been charging for a couple of weeks.

I'm thinking that the hybrid batteries are okay. Hopefully. I haven't had a chance to do the load testing everyone is talking about online.

First things first though. Replace the DC to DC converter. I found one at a junkyard nearby for $150. I'm going to throw money at this part and see if this part will work. Hopefully this part is good. Othrrwise they have warranty for it at the junkyard and will help me find another one if this was is bad. Finger crossed on this one.

Anyone have any ideas? Should I just open another thread since this one is quite old.....

I'm selling this dang car after this.....

 

To my knowledge, the DC-DC converter is not VIN specific and can be moved from car to car. The INVERTER is VIN specific and requires programming.

Does DC-DC output change with rpm?

What code(s) are you getting?

 

Haven't checked for voltage fluctuations. But it's definitely not above 13.5 volts like it's supposed to.

I'm getting code P1575. Also I didn't realize the DC to DC converter is a separate thing from the voltage inverter. I think this code has something to do with the inverter? If so what should I do???? What a nightmare.........

 

How was P1575 obtained?

P1575 may be caused by hybrid battery master switch off. Most other causes are related to bad connections or a failed MCM/BCM.

Have you checked the 11 tap voltages?

Again, does the voltage output vary with rpm? And you'd be surprised what Honda thinks is acceptable for charging voltage. 13.5V ain't it.

 

From PM from Omar:

For some reason my reply won't post. Here is my response to your post.
--------
Well I did disassemble the battery pack, which involves shutting off the main power switch.

Here is the whole story:
​​​​​​
Before I did anything to the car, I was getting code P0A7F which is hybrid battery pack deterioration. The red battery light was also intermittently turning on and off, and the hybrid battery wouldn't charge or hold a charge. So I planned on doing some testing.

When I disassembled the battery pack to check the voltages for each battery pack (in pairs) the values were as follows:
13.57
13.38
13.90
13.26
13.28
13.55
13.30
13.13
13.55
13.41
13.33
13.69

Yes I know that just checking the voltages alone won't tell you anything, but I noticed that the ranges are very very different. This has to tell me something right? I still need to find time to do an actual load test, but that is so time consuming.

When I assembled everything back, I was getting the other code P1575, but not the P0A7F code. I am using a Bluetooth OBD2 scanner and torque pro on my Android phone and have reset the code. It has came back after some driving. A lot of master mechanic shun these bcz they say it can screw with the ECU. I'm afraid it might have made things worse.......

With the current situation:
With battery disconnected and revving up to 3000 rpm, the volatage went from 9v at idle to 14.13v at 3000 RPM. Btw it's idling at 1000 RPM which is not normal. 9v is ridiculously low and 14v is way too high.

When battery was connected, the voltage stayed at 12.04V even at 3000 RPM. This is with a brand new battery. The old one was bludging, and I think bcz it was over charging from the 14v.

So is there something I was supposed to do after the battery pack assembly? Like some kind of reset procedure?

​​​​​​​Please guide me on what the 11 tap voltages are.

​​​​​​​Thanks again.