I'm trying to get the codes from my 98 Chevy c3500 dually 7.4/4l80e but can't afford a code reader and am to busy with work to go get it read. Is there a trick to pulling up codes on this truck? My transmission sometime will start shifting late and hard thru every gear and throw a check engine light and the all the sudden it's right back to being Norma like it should and light goes away. Any ideas?

 

you can't get codes from an obd II vehicle, 1996 to present, without a scan tool.
autozone will pull codes for free.