Pulsing H lights (1 Viewer)

[Midwestcruiser]

After exhausting the search method, I come to the group to hopefully find an answer to my pulsing headlamps when I am driving.(upgraded to the ARB lamp harness)
There are posts similar to what I have going on but the basic remedies have not changed anything.(grounds, vr, belt etc)
Local parts shop are no help testing the alternator.
Just replaced the 3 terminal voltage reglator with a reman toyota

1970 f engine
Not sure if this could help with an answer but when I check the voltage at the regulator (f terminal) with the engine at fast idle it is an on/off signal)-shouldn't it be constant?
the voltage at the (ig) terminal pulses at varying voltage but does not go on/off like the (f) terminal
Could this be an issue with the alternator?

 

[DiHrdBowTi]

If i recall the ig is basically the switch to turn on the alternator. If that's pulsing then i would think the output will as well.

 

[platypusREX]

Pulsing while driving or at a stop light? Just making sure.

 

[Midwestcruiser]

It does it whether parked or driving but at a high idle/throttle applied and the alternator is putting out power.
I guess a more basic question is: should the current at the (F) terminal on the voltage regulator pulse on/off or be steady? Issue with the alternator?

 

[bj40green]

The mechanical VR is basically a 3 position switch.
When the Alt is charging the switch is closed. Vign goes to the field of the Alt.
When Vign (= Battery) reaches the set point of your VR the switch goes into the "trickle charge" position which is a resistor in series to the field so that half the Voltage goes to the field.
When the Voltage goes over the set point of the VR the switch goes into the 3rd position which is to ground so no voltage to the field. This only happens when you are jump starting your truck.
The second position is what you see on your meter. On, off, on, off. Full charge, half charge, full charge, half charge. It's the set point (switching point) of your VR and means that your battery is full. To answer your question, yes the voltage is pulsing (on these old timers).

Note: If you have a solid state sealed aftermarket VR you have a fat chance that it's only a 2 way switch. Just on and off, thus no "trickle charge" position in the middle. This switching is clearly visible at your ammeter and your light system.

Hope this helps a bit.

Rudi

 

[bj40green]

Found the diagram for the 3 wire VR I was talking about


Rudi

 

[Cruiser1975]

Found the diagram for the 3 wire VR I was talking about

Rudi

Awesome explanation! As there is SIGNIFICANT dimming of the light system at idle speeds, to the point I feel it's causing my stereo/hi-fi system to clip out, I wonder if there is an updated Voltage Regulator system I could install in my 6/75 FJ 40? Would LOVE to have a steady/stable voltage for my accessories and lights!

 

[bj40green]

Awesome explanation! As there is SIGNIFICANT dimming of the light system at idle speeds, to the point I feel it's causing my stereo/hi-fi system to clip out, I wonder if there is an updated Voltage Regulator system I could install in my 6/75 FJ 40? Would LOVE to have a steady/stable voltage for my accessories and lights!

You can try by turning your idle rpm's a bit higher.

Rudi

 

[Stumpalama]

Check the voltage at your battery... check that the alt isn't over charging the battery. Mine is charging @16 volts, shuts off then kicks on and cycles this way at idle.

 

[Cruiser1975]

Though I'd replaced all the electrical components- battery, alt, volt reg- my problem didn't go away. Battery wouldn't charge, headlights dim and ammeter needle dancing.
I spoke w the guru's CCOT who agreed my diagnostics were correct and suggested I replace my NEW volt regulator- supposing it was bad out of the box. Though reluctant, I did. And voila' ammeter showed a steady charge and headlights rock Solid bright. Seems the "new" replacement VR was bad outta the box.
All in all 20 man hours trying to figure this out. The satisfaction of a smooth steady charging electrical system: priceless.