Take a close look at the connectors on the cable and make sure the slides are clear. I once had a cable set where the plastic guides on the connector were a bit munged and this kept it from making good contacts. Once I cleaned up the guides it worked fine. Just for yucks I'd also check the battery compartment to make sure the previous owner didn't leave a set of bateries in it that have leaked. The Autostar works best when it has a stable power supply and an AC adapter or an external battery pack like a jumpstart battery works well in keeping the ETX-125PE humming all night long.