I own a 1988 Mazda.B2200 pickup. After it sits for a day or two the battery goes dead. I put a new battery and new alternator on it and it still goes dead. I put a test light on the negative terminal of the battery and put the other end to the disconnected negative battery clamp. The light went on and stayed on while I disconnected every fuse under the hood as well. I then disconnected the large connection on the back of the alternator and the light went out. Thought the problem was a bad diode in the alternator and replaced the alternator. Ater installing the new alternator I hooked up all the connections and the alternator and it is still doing the same thing. If I pull the large plug from the back the test light goes out the same as it did on the old alternator. Please tell me how do I find the short after pulling every fuse and the light stills stays on. I am at wits end.
Thanks Doug

 

Have you checked the ignition switch?

 

No I havent.Tested both wires at the connector on the back of the alternator. the yellow wire is hot with key off and that shouldnt be. Going to have to get a wiring diagram. Does anyone out there have one?