Can anyone help me figure this out? I looked in my Haynes manual, and it says I need a volt meter and some other things to get the codes off. I don't have the tools to make this happen. Could it simply be a wire that wasn't connetect properly that maybe came off? I just wonder because not a week ago they had the engine out of it.

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94 Ford Ranger XLT 4x4
Extended Cab .
4.0 Automatic.