Lights dim question about the 81 and 84 Accords

Lucky me, I have 2 old Accords in really nice shape. What's even weirder is they both have this dimming issue, but it dims at different times.

On the 81 Accord, the lights dim and the fan is not as "powerful" when the headlights are turned on. If the headlights are turned on and I use the turn signal, the little gear light on the tach. dims when the turn light is actually lit up. It's like my dash light slightly dim in unison with the exterior bulbs actually being lit during the blinking stage. I turn off the headlights and the blower goes "faster" (yeah, super tornado) and the dome light will be brighter. The little gear indicator also glows a darker green.

On the 84 Accord, the lights on the dash grow brighter as I give it gas. The headlights also get brighter if I hit the gas (and slightly dimmer if I just idle). None of the issues is super noticeable or anything, but they are a warning sign of either a voltage regulator or alternator, right? I probably just notice them more because the cars are in storage and it's dark in there, so I turn on the headlights.

So which sounds like a regulator and which sounds like the alternator? At this stage the voltage reg. will be easier to do. I guess I'm just lazy right now and looking for the quick fix. Thanks!

I'd say both of them with regulator going out. On your 81 it could be grounding issues or dying alternator (brushes?). I'm having the exact same problem with my car as your 81 and never got around to replace the regulator. You could take apart the regulator and check the contacts and see if its fine. Mine are burned so bad, I filed them to shape and readjust. It helped a bit with the dimming lights, but its still there, just not as noticeable like what it used to.

My 84 has always had "brighter" headlights above 1000RPMS. The alternators in these cars are only 60amps, IIRC. I'm on my 3rd alternator since I've had the car, so maybe something is wrong. Maybe it's the 3 amps and the power inverter I have in my car... But I've replaced all my grounds and main wires with new, bigger wires, and it does the same thing, even with the stereo off.

If you look at the output for the alt in the FSM, you'll see that the output drops at a certain RPM. Also, any load will initially cause a slight drop in voltage throughout the electrical system, and hence the lighting dim that you're seeing. I could be wrong, but I wouldn't worry too much about it unless the dimming is across all your lights, and is an extremely significant dim in the lights.

My friend's car has a noisy GM fuel pump. You can hear the pump speed up and slow down ever-so-slightly with the turn signals. I think it's just the nature of DC electrical systems.

Yeah, it seems all my Hondas over the years have gotten slightly brighter when I revved up the mighty engines. Plus, the storage area is SO dark that I prolly just notice it that much more due to the pitch black... it really isn't that significant at all in the bigger picture (the open roads). I think I'll just start looking for a regulator on the cheap and put them in as I acquire them. I think the electrical systems are healthy in both whips; nothing seems out of the ordinary otherwise. Just one of those things we notice as underbuilt all these years later (blower motors, ANY torque, stereos, etc etc). Kinda makes it cool I suppose.

Both my 82 and 83 would "brighten" when revved above idle. The "brake" warning light on the dash of my Toyota dims with the turn signals, and the alternator is brand new. I wouldn't worry about either problem. Fix it when it breaks.

Forgot to add that my car have the lights brighten above idle. I noticed that my voltmeter that whenever I revved the engine from idle the voltage would jump to almost 15v and drops to 14.5 and stay that way. Its like the regulator has some delay in cutting off the alternator output or something. I want to replace mine!!!