Originally Posted by 94SSEgold
the 94 works good. the 91 is not working at all. Please advise with it.
I can't give you any personal experience with it because I haven't checked out mine yet, but in general I think the first thing to do is to extract the light cell from the top of the dash and test it. As someone else said, you need to measure its resistance in light and in darkness to see if it falls within the proper range. While it'* unplugged, you should also measure voltage on its wiring at the connector, to make sure it'* getting what it'* supposed to. (I'm not sure if it'* supposed to get 12 volts, 5 volts, or something else; my factory manual is at home.)
That would be my starting point. You'll need to do a little careful prying up of the panel containing that light cell in order to extract it. Again, I haven't done that myself yet; maybe somebody else here has some tips on that.