OBDII Reader
Anything newer than '96 will be compliant. Could be your reader. Have you tried checking both key on-engine off and key on-engine running codes? Some cheapo readers need to be installed before you turn the key.
Depends on how old the scanner is. I have a Actron that is about 8 yrs old. Works great on my 99 Explorer and my kids 02 and 03 Chevys. it will not work on my 05 truck. Contacted Actron and was told even though the truck is obd2 they use CAN protocol.






