89 PathFinder Power Shift Indicator Light

[PFFlyer]

I need some help/direction please.......I have an 89 PF 4x4 VG30 Automatic trans. I have had this vehicle forever (or so it seems) and it has given me next to no problems! Recently I replaced the alternator-(it died)-now I have a new problem: The Power Shift Iindicator Light constantly flickers-- I can also hear a clicking that seems to be coming from inside the transmission pan. Occasionally the car has difficulty shifting from 1st to Second. Once it gets going it runs fine. I did the procedure to get theindicator light to flash a code, but all it does it flicker (in no pattern). I have had the transmission serviced and checked---they found nothing "mechanically" wrong. The shop, however, could not run diagnostics---(I live in a small Texas town of under 600 people) and Iii was told to take it to "the city" where they have such stuff. So now you are saying "well, take it there" I am a woman and just know the minute I go to the BIG shop someone is going to "see me coming". I would like to know what this might possibly be. One of those electronic transmission sensors, I'm sure...I do all of the basic work on the car myself---but this is beyond me. Thanks for your help in advance