2004 2.4 Petrol Hybrid HV Battery & Head Unit Issues

[Jonny99]

Hi All,

I bought the above Alphard 18 months ago. One of the changes we made was to replace the Head unit with an Android unit. Last summer we went to the Iberian peninsula for 7 weeks touring with no problems. 
A few weeks later just as we were setting off to Anglesey this time the van stalled. We eventually got it to our local garage who were too busy to look at it. So we decided to get it transported to a garage in Worcester that was recommended by the importer we bought the van from. They diagnosed that 2-3 cells of the hybrid battery were faulty. These were replaced. Then we were told that the original Head unit needed to be re-fitted to test the battery. We didn’t have it. We bought another from eBay but then we were told that the wiring had been bodged so much that it couldn’t be done easily. We were then told that the Head unit was used to re-charge the battery and the Android unit thus was not compatible. It’s not yet fixed as they are now looking for a different Head unit with different connections on the rear.
Can anyone suggest a way forward? Can anyone confirm that Head unit is indeed used to re-charge the HV battery.

[Picasso]

Head unit is part of the hybrid system and is used to calibrate hybrid systems

[Jonny99]

So I assume that the Head unit is used to re-charge the battery and other hybrid interfaces?

Do you know of any relevant wiring diagrams which could help my garage?

Many thanks in advance.

[smurf]

From what I have read, I would be very surprised if the stereo has any part to play in charging the HV battery. The hybrid system has its own ECU, which does connect to the headunit as it shows hybrid system info. I'd imagine anything they want to do could, and probably should, be done with techstream. Techstream will show a lot more information than the head unit ever will. Toyota did make dealer equipment for charging a flat HV battery which is easily repricated these days with cheap constant current LED drivers.