HELP! 2005 Prius warning lights - told 2 ECUs need replaced and possibly battery assembly

The battery ecu on a Gen2 counts the modules that are furthest away from the ecu (towards the right side of the car) as block 1. The modules that are closest to the ecu (left side) are block 14. Ignore what is written on the modules because it is not correct and doesn't match the numbering for the trouble codes.

Posted via the PriusChat mobile app.

 

You've been replacing wrong modules the entire time.
Gen 2 battery blocks start from the module furthest from the ecu.

Although some gens and models differ in the orientation/polarity of how the modules are arranged in the battery, what is consistent between all HV batteries is that module 1 of block 1 is the module that has a heavy orange cable connected to the (-) terminal of the module.

 

Feed the .csv into chatGPT - You may be amazed at its ability to interpret the data and be generally very useful in deed! Pretty much no question it can't answer!

 

Four year old thread, but my impression is that AI creates a reasonable sounding answer, but who knows if it's right? Admittedly I've been resisting delving into it, as yet.

Do you think it's useful for car diagnosis, with what's available to we mere users?

 

The one counterexample to this that I know of was the Gen 1 Prius (2001–2003), where the #1 module was the one at the + end. Whether all the generations after that follow a "count from − end" rule, I'm not sure; usually knowing just one counterexample is enough to make me suspicious of a rule, so I feel more comfortable just looking each one up in the right manual.

One idea you can use to convince yourself is to look in the wiring diagram to see if the voltage sense wires are shown with numbers and color codes. A 2006 Gen 2 diagram shows them like this:



So in that diagram you can see that the count starts with GBB0 (the reference) and it's the blue wire with the black stripe, and the last one is VBB14 and gray with black. (And because of the way the service plug isn't right in the middle, you can pretty much tell at a glance where those are.)

While this is a Gen 2 thread, may as well state for the record:

Gen 3 has a very similar diagram, but with different colors, red for GB0 and black for VB14. (Which of course will explode the head of everybody who expects red to be + and black to be −.)

The Gen 1 diagram was a headache because it showed the colors and pin assignments but no mnemonics numbering the modules (and Gen 1 put the service plug spang in the middle of the stack of modules, so you didn't have long end/short end to go by). One had to go to the repair manual, where the page for the P3030 code had a picture that repeated the same pin assignments and colors and added mnemonics, where the + first one (gray with black) was VBB1, and the − last one (blue with black) was GBB19. Got confirmed in this post by inspecting a new Gen 1 sense harness.

And at least through the first three generations of wiring diagram, it seems nobody ever corrected the spelling 'busber'.