check engine light came on yesterday, 2004 Dakota Quad cab, 233,000 miles, V8 (engine re built in 2013 when it threw a rod). How do I check the code? I tried turning key to "on-off-on-off-on" and nothing came up. Thank you very much. (I bought this truck new in 04). Thanks.

 

Take it to an auto parts store and they will read it. Or buy yourself a code reader. They are cheap these days.

 

What happened when you tried to read codes? Did it say "P DONE"?

You also have to do it fairly quickly.

 

Yea those easy plug in testers are the way to go to test it all while it's running, an read/reset codes.Link it to a app on phone.These are becoming easier to buy in stores too.
I like mine -Live data is great!
If getting key codes-be sure your timing of key turn is in quick ,equal sequence..

 

Thank you. It didn't say anything, and when I started it up the light went out! 2 days constantly on and it disappeared. When it happens again, I'll try the faster method! I appreciate your help.