2009 electrical issues

[ComplexSuburban]

Over a year ago the cruise control stopped working. Several times in the past year I've encountered the traction control error, but always goes away within a day or so. This past week the battery went completely dead. Replaced with a brand new battery. Next day got the check engine light with p0121. I replaced the throttle position sensor. Next day check engine light is back on and now have the cod c0900. Something to do with high voltage from what I've read.

Any suggestions on what the root cause is? Are all of these issues connected to an underlying issue ?

Autozone checked the starter and alternator and they are good according to them

Thanks
ComplexSuburban

 

[zora]

the code C0900 appears to be low voltage not high.
did you have the charging system checked when you replaced the battery?
what is the battery voltage with the engine off?
what is the battery voltage with the engine running?
you are sure the battery connections are tight and clean?

 

[ComplexSuburban]

the code C0900 appears to be low voltage not high.
did you have the charging system checked when you replaced the battery?
what is the battery voltage with the engine off?
what is the battery voltage with the engine running?
you are sure the battery connections are tight and clean?

Yes charging system checked out fine.

Not sure if the battery voltage when off but it stays around 14 when running.

I'll double check the connections.

Since posting this the check engine light has went off.