Join Date: Sep 2001
Location: Temple City, Ca
Just my opinion and it seems to be shared by MAD:
I am not a fan of true one-wire alternators. They don't have the best regulator circuit in there for a car. Actually I prefer the 10 SI and the 12 SI style of alternator because you can get a replacement just about anywhere. Fixing cars on the road isn't fun and having special parts in there makes it rough. Again just my preference.
I haven't read anywhere, including Mr. Wes Vann's tech reference articles, that you need to change pulley diameters going from a DN alternator. (external regulator) to a SI alternator.
I don't remember seeing that in the MAD articles either. Some aftermarket alternators probably do have a different size pulley. The manufacturers probably felt their design needed it.
The point I was trying to make was to check the alternator output voltage at idle and check the junction block (or horn relay) at idle. As the MAD article points out, there could be a voltage drop between these 2 depending on how things are hooked up and the load the car is seeing. Wes Vann's information says to jumper the sense line to the back of the alternator. He is referring to a car that hasn't been modified with a lot of aftermarket items.
By moving the sense line further away from the alternator, the regulator sense circuit still tries to control at around 14 volts. If you tie the sense line at the horn relay, for example, it will take its reading at that junction. The voltage, on the back of the alternator, will be higher but you really only care about the junction where the wire leading inside the car is tied to. Chevy likes to tie this to the horn relay.