1973 Duster charging issue

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rp23g7

rp23g7

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Hey guys. My 73 has a issue with the charging system.

My battery was dead at work yesterday, so i called AAA and they came to test and replace it.

I needed a new bat anyway, but he said it was not getting charged. I didnt see the results though.

I checked it this morning, car running, bat voltage is 12.25 volts, so i guess it is the alt, or could it be the voltage regulator? How do you test the VR?

the VR is new though, and i replaced the engine harness with a new Evens harness just last week.
 
Im thinking that your alt is bad. You should have 13 volts at battery while running. Start car and disconnect battery. If alt is bad-engine will die. May not be the approved way for some people, but thats the back yard way lol.
I cant remember the way of easily checking the VR other than unplugging it and watching the volt change on the alt or battery +.
 
thanks guys, i disconnected the Neg cable and the car died..

I was unsure i hooked the harness up correct even though i didnt connect anything until i made sure of the wires.

Mymopar shows two single field wires on the Valiant and Dart alternator on the diagrams, but the 73 Service Manual shows one single and a dual wire field wire set up on the Valiant/Duster diagram.
 
There was a change in the wiring about that year; I can't recall the exact year but my '73 is diagram is different than the older style charging system.

I believe testing of the two systems is also different.
 
from what ive read, the old school way of checking the alt was to pull off the pos cable of the battery while the car is running. of course you dont want to do that either because it will burn up the alt. if you pull the neg it will die no matter what, you have to have a good ground for any of it to work. maybe 67Dart273 will set this straight, but in the meantime, you can get your meter out and go to work checking out the system using methods described in the thread i posted a link to
 
Well, if you keep disconnecting the battery on a running vehicle, you will keep having troubles with the charging system.

This is not a valid test for anything in an alternator equipped car. It can lead to blown diodes, burned out lamps and fried electronics.

You will never find this so called "test" in any automotive manual. Not Chilton's, Motor, Haynes, etc.

Do not remove either battery cable from the battery while the engine is running.

Buy a decent DVM, and learn to use it.

B.
 
bohica2xo said:
Well, if you keep disconnecting the battery on a running vehicle, you will keep having troubles with the charging system.

This is not a valid test for anything in an alternator equipped car. It can lead to blown diodes, burned out lamps and fried electronics.

You will never find this so called "test" in any automotive manual. Not Chilton's, Motor, Haynes, etc.

Do not remove either battery cable from the battery while the engine is running.

Buy a decent DVM, and learn to use it.

B.
Click to expand...

exactly
 
If there was another wire added to one of the field terminals on the alternator it would have to be with the dark blue wire. That is switched 12 volts. Probably just the easiest spot for the factory to tap in something like that auxilary choke heater added in 73.
Might have been for those models with their ignition module on the right inner fender too. Anyway.. the isolated field alternator has 2 field terminals and each requires only 1 wire, dark blue and green. Hope this helps.
 
Actually, it was the voltage regulator, jumpered it to ground and checked the battery, nothing, switched it out and it is charging again
 
I too would not disconnect the battery while the car is running. Bad thing can happen! You can set the system up for large voltage spikes that can blow the regulator and/or diodes in the alternator as mentioned above. Good luck.
 
The regulator must be internally bad, it wouldnt charge unless i jumpered it. put the new one on and its fine. Oh well, at least all the electrics are new now.
 
For the next time, buy a multimeter, or free w/ coupon at HF. If you measure 12 V across the 2 alternator field terminals, it should be putting out full current, which you should see on your dash ammeter. You can apply 12 V yourself with jumper wires (disconnect factory field wires). If your battery is low, and you don't measure a difference across the field wires, Vreg isn't doing its job. In your car, one field terminal should be +12 V constant (rel. to BATT-) and Vreg controls the other terminal (+12 V = off, 0 V = full on, proportions between them).
 
BillGrissom said:
For the next time, buy a multimeter, or free w/ coupon at HF. If you measure 12 V across the 2 alternator field terminals, it should be putting out full current, which you should see on your dash ammeter. You can apply 12 V yourself with jumper wires (disconnect factory field wires). If your battery is low, and you don't measure a difference across the field wires, Vreg isn't doing its job. In your car, one field terminal should be +12 V constant (rel. to BATT-) and Vreg controls the other terminal (+12 V = off, 0 V = full on, proportions between them).
Click to expand...

LOL Dash ammeter????? just kidding, you dont know the history of the car. Somewhere on here i have pictures of the wiring some whiz kid did on this car.

For a exampe, he had a radio in it and for power he had a spade connector jammed inbetween a fuse, and a quarter jammed inbetween another for the heater, the heater switch had fried itself.

I bypassed the ammeter a while ago, and rewired most of the car.

I really bought it for a parts car for the Bee as it has big bolt disk brakes and a 8 3/4 in it, but i decoded the fender tag and its actually a nicely optioned Space Duster.

I think i am actually going to sell it when i get the heads replaced on the Ram Charger, it needs a good home where someone can do the body work and restore it. HMMM if anyone is interested.

73 Space Duster

console/bucket seat car, had high backs in it.

318 car

Heavy duty cooling, 26 in radiator

racing sport mirrors

Canopy top

it had AC

2.76 sure grip

someone put dual exhaust on it, DNW driveshaft

new holley 600 with LD4B manifold

I have pics if interested
 
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