my alternator went bad last week and i changed it..... i cleared the CEL that it turned on but the CEL came back with the code 10 01, 09 01, and 02 01.

i know what the first two means but the last one(02 01) says 'Ignition signal circuit.
what does this mean?

 

all depends. you need to state what symptoms you are experiencing.

 

none, there's no symptoms realy except that i get a areal rough idles about once a week... real rough like its about to cut off... that only lasts a few minutes , but besides that the car runs fine....

 

could be time fro plugs. coul be time for some Redline SI-1 fuel system cleaner (no matter what put some of this in your tank now), could be time for you to test coils to see if they are bad (this should be the last of all things). what was your last tuneup?

 

my coils should be fine... my plugs got changed few month ago and i checked then last week and they were just like new.....
what are they really referring to when they say 'ignition circuit system'...... what are all the parts covered by this system?

 

coil(s) prob got fried when the alt went. there is a reason you are shaking to the point of almost shutting off. and that code refers to your ignition coils. perhaps you should try to pull codes again to see if a new cylinder misfire code has been set off. That will help you locate the problem.