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Electrifying Prius - P3009 HV Leak
Posted to Technical Discussion Forum on 8/30/2009 101 Replies

This vehicle is not fixed but has been diagnosed. I'm not looking for answers as to the cause of the failure but more interested in what the logical approach to find the cause of the failure would be.

I was called in to to help with this one, it is not at my shop. Originally, the car came in with a P3009 code. During the course of the diagnostic, it became a no-start. That is when I became involved with it.

Note: They did indicate that the auxillary (12 volt) battery was disconnected during the course of the P3009 diag.

What I first did was a Health Check.

Next, I pull all the DTC's from the modules and their respective Freeze Frames.


HV ECU Freeze Frame 1

HV ECU Freeze Frame 2

HV Battery ECU DTC

HV Battery ECU Freeze Frame

Engine ECU DTC

Engine ECU Freeze Frame

The P3009 code indicates that there is a insulation leak in the HV circuitry. Unfortunately, it doesn't narrow down the area of concern, it could be in the HV battery, the inverter, the frame wires, or in the transmission. In order to test for the P3009, it would involve HV leak testing with a megger, but that means each of the components would have to be isolated from each other. This could be very time consuming.

Techs in dealerships and in areas where there are a larger number of Gen I Prius'es have probably dealt with this code and failure a number of times now. It seems to be a pretty common failure and I'm sure some have struggled with it, while others probably have a good system in place for chasing the failures down. I've not seen discussed in these forums before so I thought it would be a good time as any. :-)

How should we approach this vehicle to confirm an exsistence of a HV leak and narrow it down to a certain area so we don't have to blanket test?

Is the no-start related in some way to the HV leak?

Does the P3009 Freeze Frame help in any way, to determine the area of concern?

What other data that I haven't provided, do you think would be useful?

Thanks in advance,


Harvey from British Columbia

Files Referenced:

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car Vehicle Data

2001 Toyota Prius 1.5L

Engine1.5 L

car Vehicle Data

2001 Toyota Prius 1.5L

Engine1.5 L