You need a scan tool, or cycle the key on,off,on,off,on and depending on the year either count the flashes of the check engine light or read the code in the odometer.
You hook up a scanner and check it for codes.
The codes are read with an OBD2 scanner.
There are literally hundreds of diagnostic codes that would cause the check engine light to come on. Many auto parts stores will check the codes for free and tell you what is needed to fix it.
The computer is detecting a malfunction. you need to have it checked for codes
Check engine light codes, air filter, spark plugs, tire pressure, catalytic converter ,
your main computer -pcm- is bad. This is an internal error which can only be repaired by replacement.
Random Misfire.
There are pages and pages of codes for a 2005 ram. You need to have it checked for cades to know what is the cause.
The cruise is ran by the same fuses that power the computer. You need to check the computers for trouble codes.
"c" codes are chassis codes. Such as ABS failures.
PO700 is a Tran CTRL Sys Error PO750 is a Shift Solenoid A Error
Shift Solenoid A Error