Mopar issues

By Macgyver22
Jul 11, 2011
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  1. I am working on a 73 Challenger and cannot figure out why it is not charging. Hoping someone can help. It has a 340. New enging wiring harness, voltage regulator, battery and the alternator has been tested by a shop and said to be good. Any ideas?
  2. jobeard

    jobeard TS Ambassador Posts: 9,160   +599

    the alternator has a case ground and the hot lead to the battery PLUS a small wire to the voltage regulator.

    disconnect that wire (to protect the VR) and then ground the terminal it came from.

    the Alternator will go to full output (if it's any good) and the engine will bog down in rpm from the heave load - - disconnect as soon has you have response.

    the VR is bad if you get the response noted above - - if not, the Alt is in question.
  3. Macgyver22

    Macgyver22 TS Rookie Topic Starter

    It is a 3 wire alternator. The main output and 2 field wires from the vr . One has ignition power with the key. There is no case ground. How do I full field that one. Same way? Pull the non powered field and ground the terminal it came from? Something else I find strange is the power out of the alt is 22 volts but yet I have 11.2 at the battery and other power sources. Could it be the amp gauge in the dash causing it?
  4. jobeard

    jobeard TS Ambassador Posts: 9,160   +599

    yea, it's been quite a while since I did this stuff
    yes it is - - at the ALT side in the physical mounting, not wired
    that's the idea, but the 2-wire from the VR is iffy.
    Yea, there's a key switch lead, but not to/from the VR.
    grrr, that would FRY everything in the car; charging voltage should not be more than 14.7v. 22v sounds like the coils internally are not correct.
    An alternator is a 3-phase a-c device with a diode in each loop. Sounds like one of the loops is not grounded; 11+11 = 22
    recommend you get a Chilton's Manual for that year and check it out

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