Had the heater running turned on lights zzz zzz under dash Fuse box!?

[CUCV85]

last night - Had the truck warming up with heater on.
Headed for work- Jumped in, turned on the wipers- was raining.
then turned the lights on,
got a half mile away zz zzz zzz under the dash like from the fuse box.
The lights dimed back and forth to the beat of the zz zz zzz zz zz. SO, I shut off the heater because thinking quickly oh oh no no need the lights to see.
Wipers quit working.

Drove home after work with heater going,
no lights needed, I work nights.
pulled into driveway turned on lights, checked wipers Good no issues.

It was rain not snow, so there wasn't a huge load on the wiper motor!
OK, who's got an idea?
Everything seems ok now, but I think that was a warning of some sort.

 

[HardCorps79]

Check all of your fuses. Replace the applicable ones- even if they don't look burnt out, for whatever reason, I've had this issue more than once. So far that's all it's been. If you want to hunt and peck with the multimeter there's probably a short in your accessory circuit somewhere.

 

[CUCV85]

Check all of your fuses. Replace the applicable ones- even if they don't look burnt out, for whatever reason, I've had this issue more than once. So far that's all it's been. If you want to hunt and peck with the multimeter there's probably a short in your accessory circuit somewhere.

I was thinking that's where to start. I did replace all fuses and relays, flasher ETC ECT Went right through the whole truck 3 years ago. Man I hope there's no short. Hopefully one of the fuses will look a little distorted. I've seen fuses beforeswomewhat melted looking. Mine were all good when I replaced them and looked old as dirt, maybe originals? I'll post back what I find. At least I reacted quick enough shut down the heater and the lights restored. My Gen 1 light never even flickered. I do want to rebuild both they look original and I have noticed that once in a great while that the gen 1 light will lite very dim at night with high beams on and the heater on high As many others have noticed. There's something in that heater blower wiring that excites into the gen 1 making it light up. It probably only happens to us that still run 25 year old Alternators

 

[raiburn]

Mine did something like that a coulple weeks ago, It was a loud buzzing, that got faster and higher pitch for about 4-5 seconds, and i shut the truck of. I then waited about a minute, long enough to looks for smoke, or melted wiring, and it started and everything is fine.
I agree, it seems like some sort of warning...