We have a 2012 Toyota Sienna (around 100K miles) that suddenly had all of the electrical components give out while driving. First the battery dash light came on and then shortly afterwards all of the dash lights came on. The power steering, breaks went out but we were able to get it to a parking lot. We shut the engine off and tried to turn it back on but were greeted with the clicking that often accompanies a dead battery. The AAA guy who came to jump us said that although the battery was old (Mar. 2018) it still was working properly and was fully charged. He also inspected the alternator (which we replaced in 2018) and said it looked fine. We were able to start the car and took it to our mechanic who wasn't able to find anything wrong with the battery or alternator or at all. It has turned on and not shown any sign of problems for the last week or so.
Our diagnostic tool is showing code C1241. Any suggestions or thoughts where we go from here? We don't want to drive around a car that might suddenly die on us, but no one has figured out what caused the electrical failure in the first place.
The C1241 code is typically caused by low voltage.
Intermittent problems can be really tough to find. You may have a cable working loose - check that your battery cables and connections are in good condition and tight, and check grounds.
If your battery is dated 2018, it is about due anyway to be changed. I would go ahead and do that, just to make sure.
Did the AAA guy actually jump the battery, or it was able to start again on it's own?
Yeah, a 5-year-old battery is definitely suspect even if it tests "good". (I've had batteries that test OK turn out to be bad after all.)
When the AAA guy arrived he asked us to try to start the car and it wouldn't start so he hooked up his charging pack to the battery and jumped the battery. We were able to start the car immediately. The AAA guy said that the battery already looked fully charged so he unhooked his charging pack.
If the battery were bad, could that cause an issue while driving? When the battery dash light came on we had been driving for 15-20 minutes at that point.