P3000 Error and Frame Wire Harness

I was getting a P3000 error on my daughter’s 2007 Prius with 180,000 miles. On Dr Prius I noticed that bank 6 was way overcharging on regenerative braking and all banks showed the exact same resistance. I first tried to recondition the battery using a Prolong charger and intelligent discharger that I bought a few years ago. I had purchased two Gen 2 Prolong harnesses over two years ago but only needed to recondition one battery so this was the first time for this Prius. Unfortunately when I tried to do the first charge the Prolong charger read 250 volts which meant that no connection existed. I tried to get help from the Prolong manufacturer Hybrid Automotive, however, they were not much help. George, the service rep, first asked me if I installed the harness properly. I went ahead and did a tear down and sent him a picture and didn’t get much of a response. I went ahead and removed the harness and asked George for a wiring diagram which he did not provide. Through hit and miss I figured out the wiring and determined that there was a break in the negative lead to the battery. The connector is well designed and it is impossible for a break to occur from normal wear so I concluded that this was a manufacturing flaw and that Hybrid Automotive may have poor manufacturing and testing capabilities to have produced such a faulty mission critical harness. I asked George if Hybrid Automotive would either fix the harness or provide an exchange. His response was surprising saying that because the harness was a little over their two year warranty period that my only option would be to buy a new harness. I have never experienced such poor customer support. Most companies will take care of customers when they know the error was theirs. While the Prolong system is a very well designed and effective product, it appears to be manufactured poorly and not backed up by an honorable company. I went ahead and tore down the plug and repaired Hybrid Automotive’s shoddy work. Again, if they had simply tested this harness, it would have never gone out their door. It is also scary that this is a high voltage product and you would think that Hybrid Automotive would check and double check all of their products. After fixing the harness and doing three charging/discharging cycles per the Hybrid Automotive instructions, I road tested my daughter’s Prius and saw no change and was still getting P3000 error codes every couple of minutes. The next thing that I tried was to replace the wire frame harness and replace the cells in bank 6, even though they passed a resistance test. This did the trick and the P3000 error codes disappeared. While I did not see any corrosion on the frame wire harness plug or the Battery ECU, I suspect that the Frame Wire Harness was the problem as after replacing it with a new one, Dr Prius started reading battery bank resistance correctly. It is my hope that this helps anyone else experiencing an odd P3000 error.