Scanner Plug?

I have a 1996 Dodge Grand Caravan 121,000 miles. I took the van to get inspected and the mechanic told me that I could not get it inspected because there was no power coming from the computer. The computer is working but the "plug" that hooks up to the computer is not. I obviously do not know a thing about cars :oops: but my husband knows a little and he is equally perplexed by this we have the "book" to the van as he has replaced lots of diffrent parts on the vehicle. When we asked the mechanic where we should even begin to lookto check how to fix this problem he had no answer for us. So now what? Please help!