GMC Repair: CRUISE CONTROL, cruise control module, gas mileage

Question
WE HAVE A 94 GMC 3/4 TON CONV.VAN. THE CRUISE CONTROL DOES NOT WORK.  WE HAVE BRAKE LIGHTS. WHAT ARE SOME THINGS MY HUSBND CAN CHECK ON. HE IS FAIRLY HANDY. THERE IS AN AIRBAG ON WHEEL/DRIVER OBVIOUSLY.  SOMEONE MENTIONED YOU COULD SHORT IT OUT ON ACCID, WHILE TRYING TO FIND PROBLEM.
WHERE SHOULD WE START.? MY HUSBAND REPLACED RELAY SWITCH IN 94 S-10BLAZER THANKS TO YOU. NO ONE ELSE COULD FIGURE IT OUT. THANKS FOR WISE AND CORRECT INFO. LOOKING FORWARD TO SOME IDEAS.  I MISS CRUISE CONTROL. WE TRAVEL  PLUS DOESNT IT HELP GAS MILEAGE WHEN IN TACT. THANKS AGAIN..
SANDI IN ST.L.  

Answer
First I would check for the third brake lamp, that is the only one that would interfere with cruise operation.

Then I would unplug the cruise control module and us a test lamp to check for power and ground, and for power when you hit all of the switch positions. If you have good powers, and ground to the module then the cruise module is bad. If you find that part of the switch is not sending power to the module then there is your problem.

You can short out the airbag coil if you try hard, it is not as easy as some think. If you need wiring info I will do my best to get it to you.

Also sorry for taking so long to get back to you.