I changed out a couple of low voltage batteries, every other battery is above 7.6v. The Dr. Prius app is still showing negative voltage. The car starts fine but I still have the red triangle on the dash, no codes on the OBD. Things I've replaced so far: ECU, wire frame #2 and also the service plug wires brand new and new bus bars and nuts. I've checked all of the electronic connectors and plugs near the ECU for corrosion or any burns from shorts, all clean. I know the battery fan plug can get corrosion, mine does have some but I've known about it since I got this car years ago, it never gave me problems. I've read through the forum and have seen that it could be a wire corrosion problem or ECU but I've replaced all of that and it's still giving me the same issue.
Buddy how about we go back to the battery and take some pictures of the orange cables and all of that kind of stuff You got some kind of connection problem going on here You sure you racked all the 28 modules back up like you took them apart I'd like to see pictures inside under the hood of the HD battery behind the rear seat in your car that apparently you have been working on You replacing batteries No those are modules two modules make a block cells which are inside the modules which are six of are not accessible
Did you assemble the battery with the positive and negative terminals oriented correctly? Also, visually inspect to ensure that positives and negatives alternate all the way along one side.
What does it mean if it starts normally? Does the READY sign light up? Does the combustion engine work or just turn over? Dr.Prius does not see any errors with the red triangle of death? Your adapter may be faulty. There are obvious problems with the battery and modules. There may be a current leak from several or the contacts are mixed up. Was the harness that was replaced used from Gen2 or Gen3?
If you have the MWL (master warning light) showing on the dash, you have (hybrid vehicle) codes set. The fact you don't see them means your code reader is inadequate. You cannot rely on the Dr. Prius app. It is okay for what it is made for, but it cannot read many codes, just a few cherrypicked to support its battery functions. You need a capable code reader that can read all of the ECUs and report their codes. A thread that reviews some dongle plus phone apps is here. Read the first couple of posts and then skip to the cliff notes version in post #37.
