DC/DC converter malfunction

2005 Prius. Manufacture date Dec 2004. 40200 miles. Has had 50P ECM Reprogram and 60C steering shaft. 5k service was done just Friday, 2/1. Drove normally over the weekend. Filled up on Sunday & drove to and from super bowl party after that.

Unusually cold for here this a.m. (40-45F). Started normally. Proceeded about 1 mi downhill to red light; noticed battery full at bottom of hill. Got a BEEP, red exclamation point, check engine, + "PROBLEM" on MFD. Restarted car; same lights. Was able to turn right and go into gas station; seemed to run normally. Turned off and reseated gas cap (did not seem obviously loose). Turned on: exclamation point, check engine, + red exclamation car (hybrid malfunction) on MFD. Consulted manual ("Take to dealer immediately") and called home about a ride from the dealer; got a suggestion to make sure it didn't blow all its oil out of a mis-seated filter (happened to us on another vehicle!). Turned off, checked oil (slightly overfull), turned on: no abnormal lights.

Called dealer. They suggested since the lights went off, I could drive it there, but it should be checked. Drove there uneventfully. They hooked up the computer, saying "probably the gas cap," then "Huh, I've never seen that before: DC/DC converter malfunction." I left it with them for a thorough checkout.

They called a few hours later and said apparently I'm not the first; the Toyota database said to replace a computer with an updated version. They said it'd be under the hybrid warranty and ready tomorrow.

I asked for the code: P0A78. From a little light googling, this seems to be related to TSB 02505, which seems to suggest an inverter replacement rather than ECU. Any thoughts? I suppose it's possible there are other codes they didn't read to me.

 

Yeah, I understand: I restarted 3 times and the error condition was no longer present, so the lights didn't come on anymore.

I guess my real question is what's the link between P0A78 and an ECU replacement? Is there a TSB other than 02505 (sorry I typo'd that earlier) that I'm not seeing?

 

Well, I've got the car back, and the sheet has some different information than they had given me on the phone:

CODE P0A94 INVERTER MALFUNCTION
REPLACED HYBRID ECU PER TSB EG058-06

Still no subcodes, but P0A94's been seen here before. Not sure if I actually had both P0A94 and P0A78 or what.

The TSB was discussed here also. This implies that my subcode was 588 since they decided this TSB applied. Definitely looks like a replacement rather than just a firmware update.

Someone over on the yahoo group had both P0A94 and P0A78, and had the ECU replaced.

My charge was $662.03 to the hybrid warranty. Hope that's the last I hear of it, or if not, that recurrences also fall within the warranty period!

 

Yup!

Yeah, and quite possibly not under my own power either.

I'll hope for the ECU having actually been the problem.

 

Does not sound that similar to me, except for the part where several warning lights were lit.

I'm glad I took mine to get the code read, despite my initial sense that it was probably a loose gas cap. I'll do the same thing in the future, especially for sure while it's still under the hybrid warranty.

 

Guess what! No such luck. It happened again, except that it did not clear after 4 reboots. I was on the freeway right at the exit for a toyota dealer, so I did get there on my own power. Dropped off the key & form for them to pull the codes in the morning. Unfortunately it's my least fav dealer in the area, but I guess I can't be too choosy when it's putting up hybrid system errors where the manual says take it to a dealer immediately. I have a feeling I'm joining the inverter replacement club.

 

Thanks for the file!

It's at Toyota of Pasadena. I had a less-than-pleasant experience with their service manager at the 30000 service and had been going the extra distance to Longo since then. I took it to Longo for that warranty service about a month ago; since the error messages cleared and it had just been there for a service 3 days prior, I thought it was worth driving it down there. With the lights staying on, I did not want to ignore them and keep driving. So, here's Pasadena's chance to change my mind. They should just be opening up about now, so hopefully I'll know some codes before long.

 

P0A93. I'm getting a new water pump under powertrain warranty. Is my inverter failing piece by piece?

I guess I should have started a new topic.

 

I take mostly shortish but not microscopic trips (11mi/30min partially in traffic, partially at fwy speeds), but I can think of at least one that was more like 30mi/1h each way in traffic since the Feb. ECU replacement. I live on a foothill and I work on a different foothill, so this prius goes up and down more than some. I get full green battery going down with some regularity. I have wondered at times about side effects from this lifestyle.

The idea of one inverter-related failure per calendar month is not really what I am looking for.