engine disengages after vibration

Guys I have the first generation prius. It runs great and I love the car. This vibration issue is something I noticed too but recently I have gotten alot of problems. When I start up the engine idles ar per norm but then after a few seconds the revs seem to fluctuate, my battery indicator (HV) goes from a low level to full green bar in an up and down manner. The vibration sounds and the engine then seem to free wheel, and the revs seems to increase. Accessing drive mode does not result in the car moving. It just seems to be out of gear. I have checked from the aux batteries, the HV batteries, the ECM etc.. even the pedal sensors and cant find a clue. My investigations so far has shown:
(1)no fault indications,
(2)the turtle icon is on after a few seconds into start up
(3)and the knock sensor seems to be the one which is picking up the vibration and sending a signal to the ECU.

My question is this: is it possible that the transaxle is damaged or some other component in the coupling of the PSD and the ENGINE and MG1, MG2? I need help. Where I live there is no authorised toyota dealer, and the lots of mechanics here not familiar with this baby.

 

By traction battery you mean the HV battery? I changed the AUX Battery but the problem is still there. But what do you think causes the engine to disengage and freewheel? Does that happen if your batteries are going?

 

The MFD Battery signal cct seems to stem from a NiMH battery charger in the trunk just under where the speakers are behind the back seats. There is some instructions on it but it is all in japenese. I believe the signal to the MFD comes from this unit. Maybe this is the HV control unit and charger. The high voltage connections I have to check a bit more closer to ans ur question.
Before this problem occurred I noticed the batteries would be charging all the time. I was getting a full green bar but the turtle icon would still be on. The only side effect was that on accellerating the car would be slightly sluggish.

 

It is the NHW10 but would it be much different than the 2001 NHW11? Anyway do you have any such links where I can get the info I need?

 

Are there any other suggestions out there? The HV batteries are supposed to be the same as the NHW11 since it is basically the same car modified for use in the US and Europe. The Battery voltage is definely different on the the NHW12 and later models. I believe the variances might be limited enough to work around. I find it hard to believe that the HV batteries are gone, because this problem occurred too suddenly. There was no gradual battery failure in battery life. The car was functioning normal until the vibration issue and the engine start racing away after. The battery fluctuations only begin after the vibration shutdown.

 

Ok guys here is the latest development on my situation. I have been doing engine checks, and I have cleaned the throtle plate on the throttle, cleaned the crankcase sensor, and changed the knock sensor. The HV system was rechecked, no fault indications, no slack connections etc.

The result is that the car idled smoothly for quite a while, a slight up and down change in revs at the beginning but leveling as per norm. The MFD would show that there was charging from the engine to batteries when the revs go up, and no charging when the revs go down. Which is normal indication of the MG kicking in and out. However, what I am seeing is they battery level going all the way to full green and down back to pink in a matter of 10 -15 seconds. After idling like this for about 10 mins, the engine revs go up and continues running but free wheeling, that is totally out of gear. The pedal sensor seem to have no effect on the revs.

I did this several times and without the HV battery charger plugged in and I was still getting the up and down movement in the battery level. Why would the engine just disengage? My battery checks seem to indicate the HV battery is good. If cells are bad would the battery have this effect on the engine? Or is this a mechanical problem?

 

I am presently considering to do individual checks on each cell. I think I have the resources to do so. But my biggest challenge will be finding a supplier for these individual cells. Mine are the NiMH type and each one is 7.2 volts, totalling 40 in all. With my model car, I have an inverter charger for charging the HV batteries from a 12v source. So I will try that first and see if I get improvement. So if you have potential suppliers let me kno. Also, I am wondering do I have to use a NiMH cell to replace that one or is possible to use the cells with different make-up such as lithium cells?