It's an auto 2WD, Banks Power. I keep finding the terminal on the negative post of the driver's side battery twist-able, and the wire to the fuel shutoff solenoid attaches at that point. I have shined the connector and the problem seems to have disappeared, however, the 'jaws' of the terminal cannot close completely, so the terminal can still be twisted fairly easily. I shall file away some of the 'jaw' (or whatever it's called) to permit a much better grip on the battery post. Meanwhile, I greatly appreciate all the suggestions I've received.