Electrical Issue, C1241 code thrown

Hello Everyone,

I've had a 2006 Prius now for a little over 3 years. Overall it's been a good car, but I'm now having an issue that has occured a few times and I'd like to get an idea of what might be wrong with it.

About 3 months ago, there was a problem that would occur while driving -- the loud constant beep along with most of the dash lights would come on (noticeably the red "BRAKE" light -- as if the parking brake were engaged) and I would lose brake pressure. There were a bunch of DTC codes thrown (U0293 and U0111 were among them, if I remember correctly, as well as a bunch of C-codes). I took it to the dealer, they were floating around possiblities of a bad inverter, bad DC-DC converter, bad acctuator, etc. The 12V battery was testing a bit low and it was 5 years old or so, so they replaced that and the problem (or at least the signs of the problem) disappeared.

Fast forward to last week, the dash lights up again (although no red BRAKE light) and the code thrown is P0A93. I check the coolant reservoir and sure enough, it is still. Since I'm in the middle of a road trip, the next day I take it to the dealer, have the inverter coolant pump replaced, and I am back on the road with seemingly no more problems.

Today, the dash lights up again and the loud, high pitch starts screaming again, brakes are soft as well. I pull off the interstate, turn off the car, turn it back on. The triangle and the check engine are still on, but the red BRAKE light is off -- no warning pitch either. The car seems to drive like normal and the brakes feel fine. I take it to an Advance Auto store to get a code reader and the only one their reader can find is C1241. Upon leaving the store, I drive the car back home (about 60 mile trip) with nothing out of the ordinary happening. All the lights have disappeared and the car drove, sounded, smelled, and felt like normal. Not sure if this is relevant, but today it was humid and rainy, in fact it has been rainy all week (I'm in Rochester, NY right now). When this problem first started in April, I was in Florida.

I'm planning to take it to a Toyota dealer tomorrow to get a more thorough diagnostic. I don't have the tools or experience to DIY any electrical issues on my Prius. I've been reading through some of the Prius Chat threads that mention the C1241 code and it sounds like there is a bad electrical connection somewhere. Most people seem to have other codes in tandem with the C1241, and maybe the Techstream will show them tomorrow. Does anyone have any insight as to what might be going on before I simply take the dealer's word for the problem?

 

Update: Took it to the dealer at which a tech ran the Techstream (see attached). While he did not see the code that I saw yesterday (C1421), he did see a P0A08 code (with subcode 264). He reset the code and drove it for about 11 miles without any code recurrence. The guy at the service desk said there was a laundry list of tests they could do, but he said that since the code was no longer active it wasn't worth paying for until the problem happens again.

So the questions I still have are:

1) Is the P0A08 code related in any way to the code I pulled yesterday (C1241) or the problem I had last week with the inverter coolant pump and the P0A93 code? The pump was replaced and the coolant appears agitated in the reservoir every time I check. Could any damage have been done in the 90 miles or so that I drove the car between when the old inverter pump first tripped a code and was replaced? If so, why did it take a week and 500 miles for the P0A08-264 code to trigger?

2) The current problem (all those dash lights and braking issue) happened back in April prior to the 12V battery replacement and were not seen again until yesterday. Is this problem something that will continue to happen more frequently as some part wears/ages (like those problems associated with a failing HV battery, fouled plugs, leaky , etc.), or is the problem conditional (driving at a partcular speed, in certain types of weather, etc.)?

3) Is the current problem part of the reason why sometimes a light (tail light or headlight) sometimes goes out while driving? Usually, turning the car off and on fixes this problem with the lights and they work fine afterwards. The lights themselves do not seem to be broken.

 

At some point -- yes, but the car only has 96k miles on it. I was hoping it would last at least another 4 or 5 years. My last car was a Corolla and it went 357,000 miles over 19 years. Is 200,000 miles unreasonable for a Prius?

 

Thanks, SFO!

I wish I had the tools and know-how to attempt all those tests in the write-up. I don't have a garage or a second car to drive while I fiddle on the Prius. I can at least take a look at the connections. When it says make sure "they are not loose," what exactly am I looking for? What would "loose" look/feel like? Is it simply that a bolt isn't tight enough or a clip in all the way? Also, when it says check to see that "there is no burnout" on the connectors, what would burnout look like? Trying to Google examples simply brings up videos of people smoking their tires.

 

Interesting in what way? What should the voltage be?