Does anyone know what the small cable with the plastic end that connects to the voltage regulator does? I just replaced my voltage regulator with one off eBay that didn't have the metal post for that cable to connect to. So now that cable is flyin in the breeze.

 

That wire basically turns the alternator ON to charge the battery. Referred to as the sense wire. What kind of connection of the alternator do you have now? Its easy to change the connector type for the harness.

 

Thanks for the response. The aftermarket voltage regulator did not have a metal rectangular post like the Bosch has so once I installed it there was nothing to connect that "sense wire" to. So I just left it disconnected. The car drove well and the volts seemed to be in an appropriate range like 13.9 running without many electronics on and 13.5 with the A/C and brights on etc. However, something drained the battery overnight with that aftermarket voltage regulator installed so I replaced my original bosch one and ran an extra 4 gauge cable from the positive terminal of the battery to the positive terminal on the alternator. Also put a 100amp fuse in that cable line using an ANL fuse holder/connector. I also connected the "sense wire" back up. Now running, the car's volts are at 13.8 without electronics on and 13.4 or so with them on.

 

If it ain't broke don't fix it. Sounds like you should leave it alone since it is working. Have a plan in case anything happens later.

 

The pcm regulates voltage in most obdII cars, the "voltage regulator" is more like a relay, sending and receiving voltage information between the alternator and computer and activating the field inside the alternator. Changing to an aftermarket unit (and when i see aftermarket 9 times out of 10 its also generic) will work because it is a self contained unit, but, the pcm wont interact with it which can cause other issues as you found out.