went to town today in truck and when i started it to go back home the check engine light came on..need to know what triggers this as i have good oil pressure on aftermarket guage..charging system is working and no lights on information panel.any suggestions thanks in advance

 

im sure someone will give you some better answers for this but in the mean time try cycling your ignition three times w/o actually turning it on and it should blink your codes to you via the check engine light. if you do a search on this you will probably find more details on this like the corresponding codes. sorry i could not be more help. good lucky!

 

The sticky tells how to check the codes.

 

ok finally had time to check codes and seems that i have a 12..which is batt connection prob in last 50 starts..no biggie...second is 23 which says air temp sensor shorted or open and 41 which says generator field not switching properly..ok that being said what is the air temp sensor and how do i check that..and then also how to check gen field and fixes on these..also could something have triggered these without an actual malfunction?..ways to reset check light..thanks for any and all advice..truck runs fine and starts every time so obviously not to major of a problem...thanks again

 

Air temp sensor is in the top of the manifold, make sure the wires look good and that it's plugged in.

Is the truck charging properly? The code 41 is telling you that something is up with the charging system, it's often bad brushes in the alt causing it.

 

ok finally had time to check things out air temp sensor appears to be plugged in and wiring seems ok so how do i proceed to check from here also alt at batt is putting out 14.4 volts so that seems to work also..lights are bright and wipers all function normal speed not slow like when just running on batt as well as good starts on cool mornings so seems to do its job....how do i reset the check engine light after i determine the problem with the air sensor...thanks for the help

 

The MIL will turn off if the problem goes away, even though the code will be stored. The codes can be cleared by disconnecting the battery. That will set a code 12 but that does not trigger an MIL.