If it's a Federal car as opposed to a California car, you won't need a scanner, only a DMM with a Duty Cycle scale. Connect to pin 3 of the round connector on the ignition control module located on the drivers side fender well, and to ground. Read the duty cycle with Key On Engine Off(KOEO) as I recall. If there is a code it will be one of ten codes indicated by 10%, 20%, 30%........ etc.

A very small amount of searching will turn up the key for these ten codes. It can be found on the factory service manual CD as well as this site via search.

Happy Hunting,
Larry