Have a 1997 1500 with 200,000 miles on it. Took it in to get State Emissions done, 2 different places said we can't read anything. I put my Autel MS 300 OBDII scanner on it and it showed no codes. I also did the key on off, on, off, on and it showed no codes, but it never gave me the 55 code saying all is complete.
I checked the wiring at the diagnostic connector---pins look fine also.
Truck seems to run just fine.
Has anyone got any Ideas????

 

Did you reset the pcm within the past 200 miles

 

No, Should I, and if so how do I do that?

 

Disconnect the Negative battery cable for a few minutes.

 

When you reset the pcm it can take up to 200 miles for it to be ready to read the codes from.

If you can drive it another 200 miles if needed I would reset the pcm and then see if you still have problems reading, should really only take about 50 miles for it to be ready.

To reset, disconnect on battery cable and turn your headlights on for 30 seconds turns lights back off and reconnect cable, you might notice a struggleing idle but that is normal