C1241 after replacing 12v battery

I the red triangle on my 2004 Prius (generation 2, gen 2). After reading posts it seemed like it could be a bad 12v battery although it wasn't that old. It read 11.9v during operation. I replaced the battery and the triangle went away. However, the C1241 error code was still current. Reading through other threads there are a number of things that could be indicated, but I wanted to give some background.

My speedometer display went out and I read about the bad capacitor issue on these forums. I disassembled the dash and pulled out the combination meter that was listed as a probable cause and confirmed that the capacitor read low on my multimeter and was the original one. I got a refurbished combo meter and put it in, but didn't get the connectors right so I had to pull it apart again and reseat them, and then pull part of the dash off again because I didn't plug in the passenger air bag completely. So far, none of this should apply to the C1241 error code. A month or so later my multi-functional display became wonky and the air conditioner wasn't controllable through it and the radio started to go in and out. I bought an Innova 5160rs computer code reader so I would feel less ignorant and it told me I had a bad inverter cooling pump. I thought maybe this had something to do with the air conditioning problem so I replaced it. However, I neglected to ensure I replaced the coolant that spilled during the fix. Continued to have the MFD issue with air and radio (check the air conditioner connection) which sometimes worked and sometimes didn't, but then I saw something online which made me check the coolant level and I filled it up and bled the system. I also removed the MFD and put it back in to ensure the connections were secure. Now I was worried that I had damaged something when the coolant was low. Shortly afterwards I got the red triangle and after doing some reading here I replaced the 12v battery and the triangle went away. However, the C1241 error code remained. The MFD is better now, in that the air conditioning works through the display, but the radio is completely silent even though the display and controls indicate that it's changing stations and all.

So, I've got several questions.

• When I replaced the combo meter, which requires pulling out the MFD, could I have damaged it since that year has the issue that Hobbit noted had a manufacturing defect that is prone to having a communication issue that throws the air conditioner message?
• Could I have damaged something with the low coolant that may now be a problem throwing the C1241 error code?
• It's an old car. Is everything just starting to fail at once?
• Given everything I messed with, may I have created these problems I'm now experiencing?
• What the best, systematic way, to check systems to start honing in on what the problem is and if they are related or completely unrelated to each other?
• If I get Steve at AutoBeYours to fix the MFD, will that have no effect on the C1241 error code?
• Is there a reset that I should have done after replacing the 12v battery? Am I chasing a ghost that was already exorcised when I replaced the battery?

Thanks,

-Josh

 

In what way? It resolved the red triangle and the on-board system check shows it as 12.4 volts when in accessory mode. I figured that was a good enough check for it. The old battery was showing 11.9 volts. I could hook up my multimeter, but it would probably only read higher at the battery if the computer is reading 12.4.