Leave the ground cable connected and remove the positive cable, and just tap the cable to the battery post. If you see a small spark, there's a parasitic drain. If it's drawing enough current to make a test light come on full brightness when connected between the battery post and the cable, the battery will be drained overnight, or within a few hours. Start disconnecting circuits or pulling fuses one at a time until the light dims considerably or goes out, then trace that circuit to find the source of the drain. Start with the big 12 volt output lead of the alternator- - - -a leaky diode is the most common cause of parasitic battery drain on an alternator-equipped vehicle. Even with a bad diode, the voltage output will be right, but the charging current capacity will be drastically reduced.
Jerry
