we are dealing with a 91 celica...the positive terminal has grounded out before(issue resolved)the alternator B lead (battery) had burnt before(issue resolved) and we have went through 6 alternators(new from discount ap)popping diodes, a lot of that was not me;)...anyway the leads to the three prong plug that comes from the harness to the alt had some bad wires (lamp and sencing)the other is ignition but it ws ok.I had thought that possibly the battery wire coming from the alt was shorting to ground causing this but it's not...trust me.Now the question:"would the alternator not being able to sence the voltage from the battery cause it to pop diode/triodes?"