Getting Negative HV Battery voltage readings

Since block #1 reads mostly normal, I suspect that the wiring to the remaining blocks is messed up. This might be the simple result of a broken or badly corroded sensor wire connection in the HV pack. The voltage of each module depends on the connections before it, so break a link in the chain, and the chain gets shorter. In this case, you seem to have a single module chain.

 

Voltage harness, aka Wire Frame #2 is likely your problem and it only costs $50 for a new one from Toyota... However Torque app sucks and that could actually be the problem. To be certain before you pull the pack to replace wire frame, try using Dr. Prius app... Also likely you have a bad module based on P3015 code, but one thing at a time.

 

I'm going to go with this being a Torque problem.

The P0A80 and P3015 are pretty clear on their meaning, but having 13 blocks all reading a -330v is most likely a programming error on the app....

 

That is the plug end of wire frame #2. Good call for those who said damaged wires, because that is most likely a goner.

The corrosion levels you see are very typical. You definitely want to take a look at the ecu pins.

 

The voltage sensing plug going into the ECU does indeed have healthy looking pins, but that black spot on the side of the plug is concerning. What does it look like in the socket? Perhaps pulling the ECU and taking it's cover off and looking inside will allow you to confirm it's nothing of concern?

 

The plug on Wire Frame #2 looks like it has seen some arcing. (circled)

 

Yeah, but he said the pins looked clean... But I agree, that black spot on outside of plug may indicate otherwise... I told him to look closer, so we'll see what he says.

 

The arcing is not good, those energetic electrons went somewhere, likely into the HV control board

By the looks of the modules, this pack has been apart before and I think more than once. AND, it appears one of them is leaking at the bottom

 

Depends on what the meaning of 'normal' is.



It is something we've heard of.

Yours looks mild at this point. Some hit the jackpot:

 

HW Store bolts are fine, just make SURE they are the correct length.

 

@fullylaced1

If you're in no rush for these fasteners, PM me your shipping address and I'll send you a handful so you can do the job right. I have hundreds, if not thousands, of extras.

If you'd like, I can also send a used OEM harness (that doesn't have arc damage). I'm sure I can find one that's in decent shape. May need corrosion cleaned off the bus bars though.

 

I don't think you could draw that conclusion. It is a known issue and one that no one has been able to explain, to date. Most people fix it by replacing the ECU with a good one, one where the plug has no corrosion (and obviously functions properly). It is possible to repair it when it is not too bad like yours. You just need to get a new plug and be good at board level repair.

No, there is no programming required. Just swap them over and you are good to go.

 

My guess is this another example of an "el cheapo" pack bought by the previous owner so A) they could fix the trouble lights and B) sell it. It's a common occurence.

 

The level of corrosion on those pins isn't all that bad. There's a LOT worse out there that still work fine. I've got some photos from aa 2006 I recently purchased where the car had the P0A80, but was still running. It had 100x as much buildup as your photo. I was amazed. Purchase some electrical contact cleaner and some strong q-tips. I'd be willing to say you can probably get it cleaned up pretty well. I wouldn't put it in a battery I was selling to a customer, but I would be ok using it in one of my own batteries.

 

For the non-believers.....the corrosion was bad enough that once it was all cleaned off, it had eaten away so much of the pin, that the pin fell off when I set the ecu on my workbench. Yet, the car only had a P0A80 and still ran ok.