Transaxle Failure

[dailyphotofix]

Hi there,

I have a 05 Prius with 127k miles on it. A bunch of lights came on when I was driving the other day, along with a not so good sound when slowing down. I had the car towed to the dealer and they came up with these codes: P0A90, P0A09, B2799, P0300, P0302, P0303, P0304.
They told me that means the transaxle needs to be replaced. They quoted me $4800, 4k for parts and $800 labor.

I bought a Factory Manual and a transaxle off ebay for $700 and am planning on putting it in myself next weekend.

I have seen the article on Arts Automotive about replacing a gen1 transaxle. Has anyone done this to a gen2? Any advice?

I will be sure to post photos of the repair. Thanks a lot!

[bwilson4web]

Interesting!

Any symptoms before the failure, unusual noises?

Take lots of photos. Folks will be fascinated with your progress.

Bob Wilson

[a priori]

Thank you for allowing all of us to tag along from the beginning of this process.

When you post photos, please try to provide a log in which you describe what each photo represents.

By the way: This has to rank as one of the better first posts on PriusChat!!

[tochatihu]

Yes an excellent first post gung-ho attitude, but sad that you got hit with the apparently rare failuerein your model.

The folks at Art's are communicative by email so I am sure they would be willing to share hints on the task you face. As with all major Prius projects I suppose the first step is the same - remove the windshield wipers

My concern is the possibility of collateral damage to the electronics, and I don't know if your DTC list allows us to exclude that. Maybe ask Art that also?

[dailyphotofix]

Originally Posted by bwilson4web

Interesting!

Any symptoms before the failure, unusual noises?

Take lots of photos. Folks will be fascinated with your progress.

Bob Wilson

Absolutely no unusual noises, which is what was strange. I pulled out of the parking lot and the lights came on at the same time the noise started.

I will be taking lots of photos. It might be a week until I start since I just ordered the transaxle, but I will keep you updated.

[dailyphotofix]

Originally Posted by a priori

Thank you for allowing all of us to tag along from the beginning of this process.

When you post photos, please try to provide a log in which you describe what each photo represents.

By the way: This has to rank as one of the better first posts on PriusChat!!

Thanks! I wish it were not such an interesting post! Cuz then I would not be in this situation...but hey life will go on and I will have some good experience.

Will do, as far as the photos go. I will try to take as many photos as I can.

[Mike Dimmick]

You can look up the codes in your new Factory Manual.

P0A90 is Drive Motor "A" Performance. It actually refers to any part of the transaxle. There are a bunch of subcodes that indicate more closely what is wrong - some indicate MG1, some indicate the input, some indicate the output or MG2. However, if Art's experience is anything to go by, you'll find a rebuild difficult. I would check that the subcode isn't 241, which indicates a transmission input damper failure. (You still have to separate the engine and transaxle to get at this part, so it wouldn't reduce labour very much, and there's a fair bit of diagnosis before reaching the 'replace input damper' step.)

Subcode 509 can potentially indicate an inverter failure, rather than a transaxle failure. The diagnosis asks you to check the resistances of the motor windings. Code 604 and 605 ask you to check the battery current sensor before replacing the transaxle.

P0A09 indicates that one of the signal lines between the DC/DC converter and the HV ECU is stuck low. It looks like these are digital comms signals that are expected to pulse between low and high voltages - voltages close to the ground point or the aux battery voltage are not expected. You should check for a short here first - if the DC/DC converter is shorted out, it could well be dragging down the traction battery voltage and causing the other problems.

B2799 is an immobilizer code. Given the other symptoms I think it's likely to be logged simply because the READY signal wasn't received within 10 seconds of pressing the power button and can probably be ignored. It might be worth checking for shorts in the connection between the HV ECU and the transponder key ECU.

P0300-P0304 are misfire codes. The last digit indicates the cylinder that misfired; P0300 is a general misfire code. If there are problems in the transaxle the engine is unlikely to start or run properly; I suspect these are symptoms rather than causes.

How much diagnosis did the dealer do before announcing you needed a new transaxle?

[dailyphotofix]

Originally Posted by tochatihu

Yes an excellent first post gung-ho attitude, but sad that you got hit with the apparently rare failuerein your model.

The folks at Art's are communicative by email so I am sure they would be willing to share hints on the task you face. As with all major Prius projects I suppose the first step is the same - remove the windshield wipers

My concern is the possibility of collateral damage to the electronics, and I don't know if your DTC list allows us to exclude that. Maybe ask Art that also?

Yeah, it almost looks like the inverter is blown as well according to the codes...I will check with Art's as well as the dealer.

[dailyphotofix]

Originally Posted by Mike Dimmick

You can look up the codes in your new Factory Manual.

P0A90 is Drive Motor "A" Performance. It actually refers to any part of the transaxle. There are a bunch of subcodes that indicate more closely what is wrong - some indicate MG1, some indicate the input, some indicate the output or MG2. However, if Art's experience is anything to go by, you'll find a rebuild difficult. I would check that the subcode isn't 241, which indicates a transmission input damper failure. (You still have to separate the engine and transaxle to get at this part, so it wouldn't reduce labour very much, and there's a fair bit of diagnosis before reaching the 'replace input damper' step.)

Subcode 509 can potentially indicate an inverter failure, rather than a transaxle failure. The diagnosis asks you to check the resistances of the motor windings. Code 604 and 605 ask you to check the battery current sensor before replacing the transaxle.

P0A09 indicates that one of the signal lines between the DC/DC converter and the HV ECU is stuck low. It looks like these are digital comms signals that are expected to pulse between low and high voltages - voltages close to the ground point or the aux battery voltage are not expected. You should check for a short here first - if the DC/DC converter is shorted out, it could well be dragging down the traction battery voltage and causing the other problems.

B2799 is an immobilizer code. Given the other symptoms I think it's likely to be logged simply because the READY signal wasn't received within 10 seconds of pressing the power button and can probably be ignored. It might be worth checking for shorts in the connection between the HV ECU and the transponder key ECU.

P0300-P0304 are misfire codes. The last digit indicates the cylinder that misfired; P0300 is a general misfire code. If there are problems in the transaxle the engine is unlikely to start or run properly; I suspect these are symptoms rather than causes.

How much diagnosis did the dealer do before announcing you needed a new transaxle?

The dealer told me that they checked each individual component since all the different codes came up. I am getting the car back today and I will check all the components to double check.

Thanks for the advice on the input dampener. I will check into that.

[richard schumacher]

Yeesh! Is there any other history behind this?