Assistance, please, in diagnosing charging system.

Early C Bodies - The Slab Side Years

  1. Crown of 66

    Crown of 66 New Member

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    Yes, I made the jumper connection with the car off. The more I think about it the more I think it must be this action I took that was causing the short circuit symptom:

    Set up direct charging wire (10 AWG, with crimped 14 AWG fusible link) going from ALT BATT post to starter relay batt post to bypass potential charging issues at bulkhead and/or ammeter.


    I'll try removing that when we get daylight and see if I get similar results when trying the jumper.
     
  2. Crown of 66

    Crown of 66 New Member

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    Yeah, same results with direct charging wire from ALT to starter relay removed. I think I will try to start from scratch after getting FuryGT's VR. Thanks for everyone's help!
     
  3. stubs300

    stubs300 Senior Member

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    Is that going to be the newer style or the old black box style VR?
     
  4. Crown of 66

    Crown of 66 New Member

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    Hey Stubs, not sure how to answer that - maybe some of both?! This is from the ebay listing and description:

    Mopar Voltage Regulator - Electronic Solid State with Correct Restoration Look


    This is a direct replacement for the factory mechanical voltage regulator. It uses the same connectors as the factory voltage regulators and can be used with either an electronic ignition or a points type ignition system.
     
  5. stubs300

    stubs300 Senior Member

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    Yeah, doesn't say a whole lot!
     
  6. Crown of 66

    Crown of 66 New Member

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    Lots of info on the listing, looks promising! I didn't know these VRs existed before.
     
  7. FURYGT

    FURYGT Senior Member

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    These are the solid state electronic voltage regulator that uses a circuit board to regulate voltage instead of old factory mechanical points type regulator.
     
  8. FURYGT

    FURYGT Senior Member

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    Make sure you have a good ground at the mounting holes when installing this new VR.

    Stubs, I though you would be interested in a photo of what's inside the VR. DCP_0845.JPG
     
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  9. stubs300

    stubs300 Senior Member

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    I know what the insides look like. I've just never cared for them is all, they don't work near as well as the new style VR's.
     
  10. FURYGT

    FURYGT Senior Member

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    Stubs, I wasn't sure how familiar you were these VR's.

    I agree that the 70 and up type is better but depending on how you use your car and what you have drawing juice. In my experience these work great on most situations on the 69 and earlier cars and my friends and I have some that have been our cars for 12 - 15 years with zero problems.
     
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  11. stubs300

    stubs300 Senior Member

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    My A100 had charging issues since the day I got it. Come to find out that some chowderhead [not me] borked up the wiring for the charging system, I just couldn't figure it out. Said screw it and upgraded with the newer stuff and have been happy since. The only power is the blower, wipers, lights, no radio. With a 60 amp unit, I'm more then happy with it!
     
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  12. marty koirtyohann

    marty koirtyohann New Member

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    u r messing around with it u ground one of the field wires then test the output on the battery it should make it go to full output if it dose then its the vr if not then its the alternator take it to a good rebuilding shop u need mopar only to Take the pully off it to replace the brushes more in likely hats yhe problem mopar charging system is easy to work on . do what I told u & u can find the problem (that is if u dont hav a bad wire in the system then u will need a factory service book with the wiring digrams in it .do not use the ones from the parts store tat r junk! I have been there & done that
     
  13. BillGrissom

    BillGrissom Active Member

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    Such charging questions are asked and answered a gazillion times on the A-body forum. 67Dart273 is ever patient there.
    Make it simple. Disconnect everything from the 2 field terminals. Using a multimeter, verify that both terminals are isolated from ground. The only difference in 1960's round-back alternators is that one field terminal is bolted to the housing and has no spade lug.

    Then, measure resistance between the terminals. I am guessing should be between 10 and 50 ohms. If <1 ohm or >1000 ohm the alternator is bad (field shorted to ground, broken field wires, or bad brushes). But, the factory manual should state proper readings.

    Finally, do as suggested by many. Ground one field terminal and apply BAT+ to the other terminal. That will manually force "full output". Do not have any other wires connected (like Vreg) to the fields, but do have the thick output wire connected. It should be a low resistance path thru the bulkhead, dash ammeter, bulkhead, to BAT+, but you can make it direct by running a thick jumper straight to BAT+ (termed "MAD Bypass"). Running the engine, you should see >15 VDC at the cigarette lighter (can buy a little voltmeter that plugs-in, great for monitoring so no charging surprises on long road trips), especially if you rev the engine. Don't turn on any bulbs or things you don't want damaged by over-voltage. If nothing above resting battery voltage (12.6V), verify a good ground connection from the case of the alternator thru engine block to BAT-. That was my problem once. I just needed to sand the alternator case where it bolts to the bracket. If you measure dV > 1V from case to BAT- (engine running), you have a bad ground path.

    Don't run too long as above or you will overcharge the battery. Now work on connecting the Vreg. The old typ use "high-side switching". You ground one terminal and it adjusts the other terminal up to 12.6 V to regulate field current, and thus output current. The old electro-mechanical Vreg switches on & off. The new solid-state ones probably switch on-off too, but could adjust proportionally. The 1970's Vreg use "low-side switching". You apply constant 12 V (key-switch) to one field terminal and Vreg connects the other terminal to ground on & off to regulate field current.

    For those w/ newer Mopars (say 1985+), they use the same Vreg circuit (low-side switching), but moved it into the PCM. If the Vreg circuit fails, rather than change the whole PCM, many people just intercept the wires and rig in a 1970's Vreg, plus apply a fake "I'm alive" signal to the PCM so it doesn't fuss.
     
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  14. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Grounding the field wire to test only works on cars with the '70 and up charging system.
     
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  15. Rusty

    Rusty New Member

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    I just use a cheap Fluke meter. I test output at the alternator first. If it reads 14V or above, it's OK. Then check the battery. If it's 14 or so, the connection is good then it's the battery. If the battery connection shows low voltage, it's a bad connection. FWIW, I have electronic ignition and a vr with no problem.
     
  16. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I wish I could rate that "Thanks" "Like" and "Agree"
     
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  17. John Kirby

    John Kirby New Member

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    You must be independently wealthy if you consider a Fluke multimeter cheap. Fluke is one of the best in the multimeter world and you pay for that. I do agree with the 70's electronic regulator upgrade. Did it 30+ years ago to my 66 Nyer. Helped quiet down the stereo. The points type generates a lot of noise when it's chattering away. I've since went to a 100 amp with an internal regulator and rerouted the firewall connections with 8ga wire. The alternator lead is now 4ga to a bulkhead connector. Lights and everything else runs off of it. Run them through relays and they are very bright. Did it this way to make the alt gauge work right, running the lights off the battery made it look like I was always charging when they were on. One of these days I will do more rewiring but other projects are more important right now.
     
  18. stubs300

    stubs300 Senior Member

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    Oh for cryin out loud, I agree! Why can't we have more then one choice or choose from a couple or 4?????