Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Sir, My 19993 Mustang GT 5.0 had been at the mechanic shop for three weeks. Just received it back today. Basically I had a miss. in August of this year a PA Performance 200 amp alternator was installed because the 130 amp PA Performance alternator could not keep up with the Denale cooling fans (50 amp) that were installed in July. There are also (2) 1000 watt amplifiers in this car hence the reason for the 130 amp alternator. My mechanic informed me that the alternator had a blown diode. BUT let me tell you what else happened...after installing another coil and ignition module....at 3000 rpms with the motor warmed up the RPM gauge was acting erratically and the mechanic said the motor was "breaking up". He then replaced the EEC-IV computer due to heat spots seen on the computer board. Didnt fix it. So he tested the new coil 1st and found it to be leaking oil....(ACCEL) brand. And then he tested the ignition module and it failed....that is when he went to the new alternator and tested it and it failed the diode test. My question to you is....when an alternator's diode fails and AC voltage ripples through a 1993 Mustang electrical system does it damage the computer /module and coil? And does the EEC-IV computer control the alternator in any way? Thank you for your time and attention to this matter! Love your You tube videos, thanks so much for your dedicated time to teaching us the right way!
Monde, thank you... I suppose what's confusing me the most is that if I take a low quality multimeter and I have it on DC setting I will fry that multimeter if I connect it to an AC circuit.. it just makes sense that it's no good for the electrical system that's designed for 12-volt DC
