Ford Repair: check engine light bulb burned...dosent light., computer problem, light bulb

Question
ok, first of all, i just fully repaired my transmission on my 1999 windstar, and like 2 days later the OD light started to flash on and off...i took it back to the shop and we tried to put the scanner to read the code...but there was no communication with the vehicles computer. We notice that when we open the switch to the on position with out starting the vehicle, the check engine light doesn't come on at all.  So at the shop they told me that i need to get that fixed because if the light bulb was burnt, there was no communication with the vehicles computer.....so....can i do it my self? is it true? where do i buy the check engine light bulb? any advise on what to do?
thanks i will appreciate your help.

Answer
A burned out check-engine light will NOT affect the ability to communicate with the PCM. The people at the shop should know that.   It may have a burned out bulb, but it is much more likely you are dealing with a wiring or computer problem.  Take it to at least one more shop for a second opinion.