Phizinza Posted February 8, 2009 Share Posted February 8, 2009 So when the car is off, the sense wire on the alternator (the one on the plug marked "S") has a constant draw of 0.24amps. This is a EA82 alternator (I think 87 or 88 model) on an 83 EA81 car. Is this because they aren't compatible or is it because the alternator is screwed? I looked all through the wiring diagrams and can't see how they aren't compatible. But with my knowledge of electrics and my dads knowledge and help I can't see how it could go wrong like this yet still charge fine and cut back fine? Quote Link to comment Share on other sites More sharing options...
XT6 Magic Posted February 8, 2009 Share Posted February 8, 2009 Check for bad diodes in the alternator. Quote Link to comment Share on other sites More sharing options...
Phizinza Posted February 8, 2009 Author Share Posted February 8, 2009 But how would a bad diode do this? I know diodes to just die completely. Oh and can I just make sure, even though it is all factory wiring in my car, is the sense wire supposed to be directly connected to the charge wire right after the alternator? If I have to pull the alternator apart and replace anything I'll just ditch it, I have another alternator that works well just has too much mud in it and thought I'd swap it instead of cleaning lol. Quote Link to comment Share on other sites More sharing options...
Phizinza Posted February 8, 2009 Author Share Posted February 8, 2009 Never mind. I went down the block and found two other alternators (god knows where they came from) and put one in, charges fine and only draws 0.01amps now (which might just be my multimeter). So all is good now. I still would be interested to know what went wrong, but not interested enough to open it up and investigate. Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 8, 2009 Share Posted February 8, 2009 The sense wire is for the regulator circuit inside the alternator. The regulator uses this wire to monitor the battery voltage and to set the output of the alternator to keep up with the load demand on the electrical system. The current draw you had was excessive and something was bad inside the regulator circuit. Quote Link to comment Share on other sites More sharing options...
Skip Posted February 8, 2009 Share Posted February 8, 2009 But how would a bad diode do this? I know diodes to just die completely. Phiz, as you know a diode is a one way street for electrons a "check valve "in H20 parlance. When bad... They can turn into an open circuit thus allowing no passage of current but they can also turn into a two way street allowing current in both directions. This is probably what happened to the regulator in the bad alt. Quote Link to comment Share on other sites More sharing options...
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