Dash lights oscillate

[ArtH]

My dash instrument lights oscillate, they get brighter and dimmer constantly when the light switch is on. The car is a 77 Cordoba. I recently replaced the alternator and regulator. I replaced the body to engine ground cable and have a separate wire grounding the regulator to that cable as well as grounding it to the body. The regulator is a Standard VR125T. It's a cheap part ($8.89 at Rock Auto). The alternator was purchased through a parts supplier at the dealership, but it was fairly low priced, around $25 +/- as I recall.

 

[Hemi Rebel]

just the dash lights, or all the lights?

 

[FridayGt]

i'm interested to hear how this turns out. I know mine flutter a smidge with the rumble of the engine and with the turn signals.

 

[ArtH]

just the dash lights, or all the lights?

I went out and ran some tests on it today. Battery voltage with engine off was 12.7v. I was using a digital multimeter. With the engine running I'm getting anywhere from 15.3 to 15.8 and it sometimes hits 16.0volts. That's too much IMO. I then checked both the blue and green wires that connect to the voltage regulator with the key in the ON position but without the engine running. I got battery voltage at both terminals. According to the service manual, that would indicate I have a defective voltage regulator.

I could see all dash lights pulsating or oscillating, the courtesy lights on the door panels were doing the same thing and the parking lights in front which also serve as directionals. I couldn't see the head lights doing it, maybe if I did it at night that would show up better. Voltage at the battery "bounced" around 15.3 to as high as just over 16 volts. Sooo, I'ma guessing I have a bad regulator. I've seen this before on an old GMC pick up I had and was told it was the alternator by one of our techs. However, the voltage regulator on those Delcotron alternators is inside the unit. I never bothered to test or replace it because I traded it in on a new truck.

Both the replacement alternator and regulator were relatively cheap although I've been told Standard makes a good product. The alternator came from one of our vendors and even the parts manager at the store was surprised how low the cost was. I'm pretty sure it's a 55 Amp unit which I believe was standard for that car. The car doesn't have any power units such as windows, seats only A/C. I would expect a certain amount of dip in the lights when an additional drain is put on the system such as directionals but only for a second. Normally, that is adjusted. My problem is constant and it doesn't matter if the dash lights are on or off. I can see it on the door panel courtesy lights when I open the door and the engine is running.

 

[FridayGt]

Thanks for the info on your issue. Looks like I've got another project for next weekend. Time to check my regulator out.

 

[TRAMO]

Thanks for the info on your issue. Looks like I've got another project for next weekend. Time to check my regulator out.

how did you fix it ?i have the same problem