voltage regulator 71 gtx

[71 GTX]

Hi everyone hey can you check the ground side of the voltage regulator with a continuity test. I mean can I just put a probe on the pin and the bare body and see if it is grounded?

[440roadrunner]

The only ground on a 70 or later regulator is the case itself, which MUST BE GROUNDED to the body, and the body MUST BE grounded to the engine which in turn MUST BE GROUNDED to the battery

The normal path is as follows:

Big large battery negative is connected to engine block.

approx no10 or larger jumper from battery post to body

(This is normally the separate pigtail bonded into the battery neg cable)

approx no10 or larger jumper from engine block to firewall, right at regulator mount

If you mean you want to test the regulator, Here's how it works, refer to the diagram of my old '70

http://www.flickr.com/photos/1878694...90667/sizes/o/

First, notice in the top left corner the alternator.

BAT is the large bolted connection, which goes through the firewalll connector and then back again to the battery, through the ammeter circuit.

One fld goes down to the "number one splice" which is fed hot from the key "on" and this same point also feeds power to one pin of the regulator

The way that the regulator "regulates" is by controlling the other field connection, which goes from "F" on the regulator to the other fld connection

To check the regulator, you are first going to "really" check the alternator. Unhook the regulator connector to protect the regulator from damage.

With the key on, probe both pins at the reg connector. Both should be "hot." Now, disconnect one FLD at the alternator. Probe the unconnected terminal at the alternator. If it is NOT hot, then re-connect the wire you just disconnected, and disconnect the OPPOSITE wire.

Now recheck--both FLD terminals of the alternator should be hot with the key on

If the disconnected terminal is cold, then you have bad brushes or an open rotor

If both terminals are hot, then you can check the alternator:

Connect a clip lead from the UNCONNECTED fld terminal of the alternator to ground. Start the car, do NOT rev the engine beyond a fast idle.

If the alternator and the rest of the circuit is good, it should charge "full output" depending on engine speed.

If this is OK, and the regulator was tightly mounted and grounded, then the regulator is bad

If the above "jumper" test does not cause the alternator to charge, then either you have a bad alternator, or something wrong in the wiring for the big "bat" connection, THAT is a whole 'nother story!!

[71 GTX]

Thanks alot I had a bad regulator its charging great now. your diagram was very helpful. thanks again 440roadrunner!!!!!