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electrical help needed / VR

BeavisHQV

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Hi, i took a longer ride in my 68 Coronet. Out of sudden the ammeter went to full discharge and after awhile it went to full charge. Back home i changed the VR (mechanical) and put in a new 60 amp alternator. Multimeter across the batt terminals show 12,6 volts. With engine on it show around 13 volts. Now it gets confussing. Put in another VR (electrical) and voltmeter show between 12,6 - 12,8 with engine on. So no charging.
Put back in the mech. VR out of sudden ill get 15 Volt with engine on. So went to a buddy and get a brandnew elec. VR and again its not charging. Put back the mech VR (the one that puts out 15 Volt) and all it charged was between 13,2 - 13,6 Volts.

Did a field circuit resitance test (field@reg to +@bat) and the multimeter shows around 4 - 5 Volts (manual says shoould not exceed .55 volts).

VR is grounded by a wire to the engine block.

Why isnt it charging with the electrical VR and why are the readings all over the place with the mechanical VR.

I should mention that i dropped the steering colum right before the drive to change the gearing box.

What to check next. Any help appreciated

 
under the two bolts which mount the regulator to the firewall there is still paint. I sanded the block where the ground wire goes. is that enough?
 
Make sure your ground connections at the battery are good and clean.
 
under the two bolts which mount the regulator to the firewall there is still paint. I sanded the block where the ground wire goes. is that enough?
Make sure every ground point is on clean metal. It needs to be right, not just enough. Also, see what the alternator is putting out in volts. Multi meter on volts, with red meter wire to large alternator lug. Black meter wire to ground. You need to find out if the alternator is putting out. If so, the problem is further up the wiring.
 
If the ground connections look good, do a voltage drop test on the wires and see what you get
 
I've had new VRs bad out of the box before. I had an old mechanical which charged properly and a new one that went to full retard in minutes. I have since switched out for solid state because I'm running an electronic ignition.
 
Pull the firewall bulk head connectors and make sure you do not have a melted connector in that harness in the circuit that goes through the firewall to feed the amp meter.
 
The other thing I found on my 68 is a modern battery is VERY VERY low impedance. If you were working on the car with the door open and discharged it unless your system can supply 100s of amps the battery will take all the current the alt can put out and the voltage won’t move.

Charge your battery with a stand alone charger for a few hours and try it again. Won’t tell you how I know but I won’t get that day back from my life. :)
 
still dont get it. thought i was over it. had several readings abobe 14,5 volts. today the mofo (^^) deceided to stop charging. batt dead . put another batt in , still no charging. what i dont get is that i putt a direct wire from the alt to the bat. no charging-_-
 
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