Im almost done wrapping up the 350/t56 swap in my 86 sport coupe. The car was originally a 2.8MFI auto car, with an e-fan. Soooooo..... i cannot get the alternator to charge. Brand new alternator and battery were just installed.

Belt is tight and not slipping, alternator body has good ground, and the thick red wire on the back of the alternator has battery voltage. The alt also has the small 2 wire connector, which houses a thin red and a thin brown wire. The red wire has ignition switch voltage, and the brown only has 1.8 volts, which to my understanding should have battery voltage as well.

This is my first fuel injected thirdgen, so im not familiar with the wiring. I know when i had my carb'd 305 86, the brown wire was on the same circuit as the choke heater relay.

So right now, im running a carb'd 350, with a mechanical fuel pump. Removed the entire passenger side PCM harness, as well as the PCM itself. Im also using a 4th gen starter and battery harness, if that makes any difference. Wires coming off my battery are, thick negative to engine, smaller negative to the frame. On the positive side, thick wire to the starter, smaller wire to the alternator terminal, and the third smaller wire is running my stereo amps, as it use to go to a distribution block on the 4th gens, which i don't have.

OK........ Last, im running an aftermarket controller to run the cooling fan. All factory fan relays have been removed/no longer connected. I know i read somewhere that the alt is somehow wired through the fan fuse on some cars, so i figured i throw that out there.

Sorry for the long post, just want to give as much information as possible. Really want to get this thing fixed so i can get her on the road.

 

The small brown wire is for the charge light on the dash. In the wire diagram, it shows a 10 ohm resistance wire coming from the ignition switch to the c100 connector that's tied together before it turns into a single brown wire after the c100 connector going to the alternator. Of course this is for the factory 2.8l. 12 volts is correct on the big lug on the back of the alternator. Since your probably not using the factory 2.8l alternator, which probably doesn't fit on the 350, this is probably the problem. What alternator are you using? What vehicle, engine, etc. This will make a difference of how the alternator is hooked up.

 

Using an alternator from an 87 monte carlo ss 305. Has the same 2 wire connector on the back as the 2.8 alternator.