My girlfriends mother has a 1990 ramcharger 318 4x4 auto and the maint required light has been on since she has had some work done ( I forget what it was). I was wondering if I have to reset the PCM or if there was another way to do it.

I know on my Durango, I have to disconnect the battery and hold the key to the start position for 30 secs. Is this the way to reset these old trucks as well?