GMC Truck Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter · #1 ·
I am about to go crazy if I do not find out how to properly wire the charging system for my 1975 chevy blazer. I have a 3 wire alternator that I just purchased pushing about 80 amps. The guy I just bought it from dropped a brand new motor in and I think he did not wire the battery, starter and alternator back correctly b/c he says its not charging up the battery. I took all the wire out of the engine bay b/c they were rotten and shorting out in places. I figured that was the problem. I just dont understand why from the alternator the batt connection runs up to this junction block onto the firewall and then down to the starter. The main Positive battery cable runs from the batt to the starter. I just dont see the point in these junction studs on the firewall. If anyone knows where I can find info on this wiring I would love you forever. I just want to do it right b/c we all know that the charging system is by far the most important part of our trucks. I have googled High and Low for this info and even bought a Chilton manual. Nothing!
 

·
OGMFS Member
Joined
·
1,327 Posts
If your 100% sure the alty is working, and takes this plug below. Run some 4 ga from the large post on the back of the alty to your battery positive.This is your main charge wire.

Now for the plug, the white wire is the ignition or, "I" terminal on the alty.It needs to be hot when the ignition is on, or keyed hot.In the factory harness it goes to the ignition switch through the dummy light.

The red is the sense or ,"S" terminal on the alty .It needs to be hot + constant.The regulator "senses" battery voltage here. If your not using the factory harness, you can connect this right to the back of the alt with the 4 ga. charge wire. This should get you charging.

Oh yeah, if I was you I would edit that "love you forever" stuff.:supergay: If the GMFS Strike Force sees this that, they might crush you.:read: :rofl2:

100_0828.jpg
 
1 - 2 of 2 Posts
Top