Replaced "Transmission"- Problems Return...

First I congratulate you on taking this chance with an auction vehicle. But as you' re quickly learning, a Prius is not like ordinary cars.

I'm going to assume you have some confidence in your skills and a reasonable set of metric tools. What you're going to need are:

1. Prius specific scanner - there are multiple electronic control units (ECUs) that pretty well manage the car. The biggies are hybrid vehicle, battery, and engine ECU. Other ECUs handle the keyfob and RFI key, the electronic power steering, airbags, body and other systems. See some of the other threads about your options.
2. Maintenance manuals - volume I addresses problem diagnosis and volume II handles repairs. The electrical schematics are very useful too. These can be bought on Ebay or directly from Toyota TIS. I paid a little over $300 for my set when I bought my used, 2003 Prius five years ago.

First comes diagnosis and for that you'll need a Prius specific scanner. Your options:

1. Rent Graham miniscanner - $150 tool deposit, $15/month. I have one available. This scanner covers the major codes from the hybrid vehicle, battery, and engine ECUs, the majority of problems. However, it does not read out inverter subcodes, a second layer of diagnostic information. It is NHW11 Prius specific and won't work with other cars.
2. Buy a ScanGauge - $150-$175 and add an adapter. Two users, w2co and vincent1449p have cracked the codes for the HV and battery ECU including what we think are the subcodes for the inverter. Since work continues on this unit, it has 'legs' and represents an excellent value for a purchased unit. It can also be used in other cars.
3. Buy Auto Enginuity to use with your USB equipped laptop - $400 with the Toyota option. Their support is terrible but the package covers pretty much all ECUs. It doesn't handle the inverter subcodes but it provides enough engineering data to help identify the specific failure. They offer modules for other vehicles so it shares some of the ScanGauge flexibility but did I mention their support s*cks? You'll need an adapter to avoid spiking the ABS ECU.

I do not recommend the "generic" scanners sold by auto stores and Sears. They pull emissions related data and not NHW11 Prius specific data. Sometimes you get one or two codes and a smattering of engine data but they are totally blind to the HV and battery ECU.

Bob Wilson

 

Another option is to take the car to your local Toyota dealer and pay for an hour or two of labor to have the DTC read and a diagnosis offered.

Your message above says that you thought that the inverter was damaged. Was that replaced?

The hybrid vehicle ECU controls the operation of the inverter and transaxle, BTW.

 

It sounds like you thought the inverter was faulty. Did you retrieve any codes from the vehicle prior to repairs?

It is unlikely that the inverter damaged the transaxle. If you still have the old transaxle, you may want to hang on to it.

If the vehicle's 12V battery had been disconnected during the repair, it may have taken a little time for the code to reappear. In other words, it's possible that the vehicles condition is essentially the sane as when you bought it.

Again, that is unlikely. The transaxle is a lot stronger than the inverter.

You'll need to get the current diagnostic trouble codes and subcodes.