Intermittent Negative HV Battery Voltage Readings

I have seen something similar but not the exactly the same using Techstream.

When one of the voltage sensing lines breaks a P3030 code will be set. I'm a bit surprised you're not getting that code but maybe it's one that Torque can't pick up. If you catch a P3030 code as it happens the blocks next to the break will oscillate between positive and negative. Not the crazy 300 volts you got but +18 to -18. It could be that Torque reacts differently than Techstream.

Since block 4 still had a normal reading it suggests that the problem is near there. Look very closely at the lines for blocks 3,4, and 5. When you get the battery pulled apart again disconnect the orange plug at the battery computer. Check for corrosion at the plug. For more information on battery computer corrosion read this thread.

The battery fires at ECU sense connector thread | PriusChat

Brad

 

What was your solution to this? My Prius had the same issue and every block is negative except Block 1