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Brown alternator wire on a 86 caprice classic 305 engine

the reason im trying to find this out is the car runs just off the battery. it has a new alternator battery and starter. when i put the test light on it, it does not Light up. the Other wire lighted up as positive witch i already new that my friends car showed the wire that read as nothing is supposed to b negative. but i need to no where it runs to or if i can just run a new neg from the battery or something thanks in advance.

here’s a picture

this is a pic of the 2 im talkin about


The brown wire goes to the alternator light on the dash. It is suppose to light up if there is a problem with the alternator. The Red wire is supposed to power up the regulator. This wire should carry 12V+ with the ignition on. If it has no power, then the problem is here. The alternator will not generate a charging voltage until the regulator gets power.

ok thank u i will try this and get back with u and let u no. thanks again

then if this is the problem should i replace the wire. it goes down to the starter right, i think this wire and one more are on the same screw on the starter.

the person the installed the starter did not hook the wire up i guess they forgot, but i hucked it up and the car was fine for a while then it started doing the same thing again

i unplugged the 2 piece wire harness and tested the prong that the brown wire connects to on the alternator and it showed nothing, no sparks, and no power reading, i did the same test on a regal and a malibu and they both sparked and showed a reading they showed as a negitive. so with this being said i think the alternator is bad becouse the car is still dying. i also fixed the choke and changed the batter ends that connect to the batteries.

the battery light also did not come on with the other dash lights right before u start the car, my cousin has the same car as this one and his does come on with the others. any thoughts is it the alternator

If you remove the plug from the alternator and then ground the brown wire with the ignition switch on, the battery warning light should turn on. If it doesn’t then there is a wiring problem to the light, the light is bad, or 12 volts isn’t getting to the light from the ignition switch.

The wire supplies power to the exciter in the alternator. If there is a problem with the lead then the alternator can’t function.

yep i put power to the brown wire and the battey light did come on, so we new it was the alternator so after a change of alternators and spark plugs it ran as good as new thanks for all the help

You’re welcome for the help and thanks for the update. Glad to hear you got it fixed.