Lights pulsing

[BrianX128]

So my old 1g alternator or voltage regulator may be dying. On the way home from work tonight I noticed a faint pulse in my lights. Not my headlights as they're LEDs on the old 6.9, but the faint green bulbs in the dash and any incandescent bulbs I turn on will pulse brighter and fade a bit every second, but the kicker is only above 1000 rpm.

I've had this happen before in vehicles but it usually did it at all rpms and was worse at idle this is perfect at idle and bad at rpm.. my digital volt meter says 13v at idle and 14.4 at higher rpm when the pulse starts but the pulse doesnt make it change.

It's the only old ford of mine I haven't 3 g swapped so perhaps it's time, but I have the old 1g alternators from the other trucks so what's everyone think is more likely with my issue, it or the regulator? I have one of those sitting too that was good. Dunno what I should swap first but were supposed to get some fun snow and ice Sunday and I'm on call at 4am at the hospital so this is the best winter vehicle so I'd like to mess with it tomorrow, not that it would be the end of the world if I had to drive a different one or drive without the heater to save juice if the electric gremlins die on me on the ride in or home.

 

[IDIBRONCO]

Did you try to fix the issue? What did you do? Like you, I've had it happen at idle before, but it would always stop completely with higher RPMs. I've even had it start on a truck that never did it before. And that was AFTER I changed alternators.

 

[BrianX128]

Welllll I put a new voltage regulator in. I noticed on the harness for it the plug for the third terminal in.. I believe it went "f,s,i,something" was rusted and not making good connection so I cut the harness out re stripped the wires and put new spade connectors on the wires and plugged them into the new voltage regulator and it seems good now!

 

[IDIBRONCO]

Glad to hear it.

 

[snicklas]

I wonder if that is the same thing we had issues with on our bullnose. We had the same light pulsing issue in our 83. What we found was over in the battery / voltage regulator area. It was a small box, with 2 threaded studs on it, and had 2 wires held on with nuts. The connectors on this little box were bad. Once we replaced the connectors on the wires and bolted them on, it went away. Keep in mind though, that truck was a 351 gasser, not an IDI.