ok ..my car was not charging at all so i bought a brand new battery and alternator for my 87 IROC 5.7L ... and I even had them test it before i left autozone just to make sure they were all working ... i install it into my car and it is still not charging... I took the alternator back off and tested the wires going to it .... with the key on .. battery reads 12.36V .. the red wire going to the Voltage Reg. on the alternator reads the same 12.36V .. the brown wire without a white stripe reads .004V the other brown wire with the white stripe reads zero volts...i just can't get the alternator to turn on .. my VOLT gauge does work fine ... any ideas on what my problem is .. or at least something else i can test to figure this out ... thanks matt

 

if you unplug the connector from the alternator, both brown wires should be hot when the ignition switch is turned to the run position. neither should be hot when the key is turned to the off or accessory positions.

 

should i get a reading around 12V or something lower on those brown wires when the key is on?

 

should see 12volts on both when key is on.

one brown wire is wired in series with a resistor and gets power from the guages circuit. other is a direct run from interior fusebox "c/h-fan" fuse to alternator.

 

Ran into this on my 92 3.1v6, the power for the alternator comes from the cooling fan fuse in the panel. May or may not help you. Dave Roberts

 

i will have to check that because someone has rewire the fans .. they could have cut a wire somewhere .. thanks ... any more ideas?