[Mrwood]

I have decided to use a 3 wire on my 48 chevy 250, the alt was on the engine when i first bought it, so why change it. But i dont know how to wire it. I have looked at all the post on this and cant find my answer. Can someone draw me a simple diagram so i can get this hooked up. The only wire i know how to hook up is the hot wire from the alt to the starter solinoid.The other 2 wires plug in to the Alt which is a red and brown wire, these are the ones i dont know about. Thanks for any help.

 

[docvette]

Doc here, imp:

Assuming your Body wires are unmolested and still the stock colors...

• Terminal #1 = RED 10 Gauge to PROPER FUSE LINK and to the starter solenoid BATT cable terminal.
  
  
• TERMINAL #2 = BROWN wire to the Idiot lamp.
  
  
• TERMINAL #3 = Red 12 or 14 gauge wire to the Remote sensing/Regulator..(usually on the horn relay POWER).
  
  
  
• TERMINAL or LUG #4 - BLACK 10 gauge ground to the vehicle main ground buss at or near the starter.

This is for an SI series , Internally regulated GM type Alternator...




IF it was externally regulated...

This is the bypass for it.

Doc imp:

 

[Mrwood]

Thanks, thats all i needed. Great help on this site.

 

[Mrwood]

The attachment shows how im hooking up my Alt. Can i install an ammeter between the # 1 wire that says to Ind Light.

 

[docvette]

Doc here, imp:

No, That is for idiot lamp only.

To install an AMP gauge, It must be placed in Series Between the current source (The Battery) and the Load (the Vehicle electrical system).

Traditionally, it is placed between the Battery cable at the solenoid, and the Main Fuse link , Fuse Buss wire, that supports the car's fuse panel.

A safer, Better alternative, to an AMP gauge is a Voltmeter..and it's easier to install..The + wire goes to ANY fused , switched power wire, and the - wire goes to ground..That's it~

The AMP gauge must be wired to direct (high current ) Full time Power, and you have wires under the dash that can short and start major fires, or can be hit by tools when working under the dash, (like dropping a screwdriver across the battery) A hazard you don't really need to install. Plus..If the shunt burns out..It will leave the car powerless.

Once used to a Volt gauge, It will report all the information needed to monitor your state of charge.

Doc imp:

 

[Mrwood]

Ok i got what you mean, sure dont want any fire after all this work. Thanks.

 

[Mrwood]

Well i got problems, got everything hooked up and my Alt does not work. Will have to take it to Napa tomorrow and have it tested. Hope its something simple.I hooked up the wires just like the last photo i posted. So it should have worked.

 

[docvette]

Doc here, imp:

Bummer, How did you determine it is not charging? Did you check across the battery while it was running with a DVOM, and it was less than 13.95 volts?

If you hooked it up as per your photo, it should work fine..

Be sure you have voltage at #1 and #3 (as per my photo) and it should charge if the unit is not bad.

Doc imp:

 

[Mrwood]

I checked #1 and #3, and had no voltage. So maybe its just bad. Ill keep you posted, and we will get this fixed. I dont get to excited, as there is always an answer. I could not check across the Battery as i dont have a DVOM. I will let you know more tomorrow ok. Thanks for your help.

 

[Mrwood]

Well i got my charging unit working today. Had the Alt checked out and it was ok, so i went back and checked my wires, and they were hooked up right. Well i had my Alt brackets powder coated and i was not getting any ground. Cleaned out the holes and did some small grinding on the back side of the lower bracket. Put the Alt back on and guess what? it works great. Thanks again for everyones help. Im happy now.

 

[docvette]

Doc here, imp:

Glad to hear it was simple, AND cheap to fix!! :thumbup:

Now would be a very good time to install that 10 gauge ground wire to terminal #4 (my photo) , to prevent future problems!

Doc imp:

 

[Mrwood]

Very good idea, even if i have a good ground at this time. Thanks.