C1241 is low voltage warning and C1223 is an ABS control system malfunction.

Are or could these be related? Where should I start to troubleshoot the issue?

 

How old is your battery? If you measure the voltage on the terminals while it's running, what do you read? And again with the engine stopped?

Chip H.

 

So I have the same codes...replaced my battery as it was the culprit...still have the codes, plus a new one.has to do with yaw rate and steering angle??! Any body have a clue? 2005 Gx470. Thanks

 

Check the condition of the ground straps.

Chip H.

 

could be the alt going out !!

 

I believe you may need to do a Zero Point Calibration.

http://www.toyota-4runner.org/5th-ge...libration.html

 

While I am still searching for my P0010 i came across your DTC Codes. See the Toyota Factory repair manuals. They don't make sense to me but will to someone who is more knowledgeable in Car Tech.

Hope it helps some what.