i have a 1997 dodge ram 1500 4x4 and the check engine light came on the other day. after it came on i noticed that at certain rpms and speeds the truck vibrates quite abit. the fault codes are 12 and 43 (OBD 1 system) anyone have any idea on what this could be?

 

I have a 96 and it's an OBD II however, I am not really sure but, you may in fact, have a latter PCM.

Code 12: is a battery connection code: relating to problems with the connection or, if it was disconnected within the last 50 ignition cycles.

Code 43: Primary peak circuit current is not achieved with max dwell time.

Check your ignition system: Cap, wires, and coil as a a start. You may have bad wires or a faulty coil. Also, check your plugs.