I went to pull codes on my 92 5.0 by using the jumper method but the check engine light wouldn't read out the codes, it just stayed steady on. I've read the codes before a different time using this method and it worked before. What could I be doing wrong?

 

The truck also won't start right now.

 

azone has a cheap code reader that plugs in under the hood, worth a try, to me it beats trying to count blinks

 

Or if you have an analog voltmeter you can use that as shown in JCMS pulling codes thread.