Ford Repair: 2000 Ranger 4 x 4, solenoid, overdrive

Question
I've noticed when I drive my truck that it feels as if it is slipping from overdrive to drive, only have 45,000 miles on truck. Could this be electrical? Would a Diagnostic machine help find the problem?  

Answer
Yes, there are some tests than can be done with a scanner, the overdrive I believe is controlled by a solenoid. Is the OD or check engine light blinking? If the problem is electrical one or both of those lights should come on or blink. This could also be a mechanical breakage.

Sorry, my trans knowledge is limited.