We are going to attemp to install a JC Whitney cruise control (Audiovox) on a 1999 Subaru Impreza outback sport. The directions only include the years 93-94, and there are big warnings about accidentally setting off the air bag, so we don't want to go poking around. The directions for the 93-94 say to use the green/black wire on the ECM, 4th position on the 26 pin connector. Does this sound correct. Thanks in advance.

The wiring for the ECU is completely different for those year vehicles.

 

May want to search http://www.scoobymods.com/forums I think he may have an ECU pinout

Maybe you should Disconnect the battery so the air bag doesn't break your face? Or is there some reason you can't?

Did you consider a factory cruise control kit? It should be still available for a '99. Costs more than Audiovox but all connections are simply by plugging in, and the parts are so much more solid.