Alternator Light Blinks / Flashes When Driving

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1

My Alternator Light Blinks / Flashes When Driving

1969 Cougar 390 / Automatic

I’m not a great diagnostician so please be patient.

When driving the Alternator Light Blinks / Flashes, like a turn signal indicator would when activated.

Not a flicker, but a steady blink / flash.

When I stop at a light or if it’s sitting at idle it does not.

Here’s what I’ve done so far:

Checked the battery:

Fresh off the Battery Tender = 13.15 V

12 Hours off the Battery Tender = 12.85 V

At Idle = Bounces between 14.85 V and 15.5 V

Checked Battery Terminal Connections = They are tight

Checked all connections at Voltage Regulator = They are all tight

I noticed that at idle the interior lights are flickering. When I rev the engine, they do not.

Thoughts?

Thanks in advance.

2

Take the alternator off the car. Take it to the nearest part store. They will test it to see if it is any good.

3

@Royce
Thanks for the reply.
I’ll do that, but before I do I want to give a little more information.
I just took her out for a ride.
The alternator light is still blinking / flashing like a turn signal while driving.
BUT…
When I turn on the turn signals. 4-way flashers, headlights, heater fan, and when the brake lights come on it immediately stops.
I’ve never had something like this happen…weird.
Just wanted to put that out there to see if that helps.
Thanks
Tony

4

I don’t know why that happens - the basics are what counts. I bet if you fix those it will all start working.

5

I finally found time to remove the alternator and have it tested.
They said it’s working.
See picture.

I’m guessing the next step would be the voltage regulator??

EDIT: I noticed that the current voltage regulator is a reproduction unit with yellow writing on the top.
Searching the internet, I’m finding that the reproduction units with yellow writing are for a car with air conditioning.
And, units for cars without AC have silver writing.
Could this be the issue?

Also, I noticed that my battery is slightly swollen on the “short” sides.
Should I replace it or will it be OK to use once I fix the over charging issue?
I used my battery tester and it said the battery is still good.

Thanks in advance for the assistance.
Like I said, I’m not the best diagnostician.

Cougar Alternator Test Results
Cougar Alternator Test Results1920×1440 206 KB

6

Your battery voltages look fine, and alternator tests OK. So assuming everything is wired up correctly, the voltage regulator is the most likely problem. The yellow stamped repros are a bit heavier duty, but should work even without air conditioning.