Ok, so I searched and couldn't find this one.

The other night I was doing about 65 down the highway, and I clicked on the radio, (factory Delco with tape only) and a few seconds later my headlights went from low beams to running lights. Which scared the crap out of me and my fiance, seeing as we were doing 65 in the dark in the black hills of South Dakota. lol

I have tried to duplicate it since then, and can't. However, going down the road at about 40 last night, it did it again, but the radio wasn't touched this time, it was on, but had been for two days.

I have been having problems with the power seat controls turning the dome lights on, and the door locks moving the seat off and on as well, but that all seems to point to a short in a wire under the seat or in the door jamb.

And help? Also, any way to make the headlights brighter? I've read this is a common problem,

 

It sounds like you have some pretty serious electrical gremlins in your truck that are affecting a few circuits. It will take patience and attention to detail on your end to properly diagnose the problem. There are several different circuits involved that cover a number of different wiring diagrams (power seats, power locks, interior lighting, and headlights based on what you have posted)...

Here are some diagrams (attached). What style headlights do you have (single square glass bulb for hi/lo or plastic housing with two separate smaller bulbs for hi/lo one on top of the other in the housing)?

 

Check what Kyle said & are you a newer owner to this blazer? I'd check the grounds, any & all wiring that's along the bundles for breaks & or bare wires. Might be something grounding out causing all the commotion with lights, seats etc - something common to them all, like behind a fuse panel, grommet through the firewall etc.

In my '80 Seirra Grande I hooked up the lighter (it wasn't hooked up when I got it) I just 3 way spliced it into a power all the time wire. When I pushed it in the interior lights came on lol. I didn't notice this for 3 weeks until I was driving at night.

 

Thanks for the replies. Sorry for the delay in replying, I don't have internet at home anymore, and I've been working crazy hours. Anyway...

Swartlkk: I have the plastic housing headlights. (Unfortunately.) I would rather have the sealed beams so I could just get an HID kit.

Yes, I just got the blazer a couple of weeks ago. Another problem I noticed the other night was when the turn signal is on, all of the dash lights dim with the flashing and the gauge needles move slightly as well.

Rottidog: lmao Luckily my problems are fairly intermittent. (For now anyway.) So I can still drive it while I diagnose.

I read somewhere the other day that the lumbar switch wire under the seat tends to get the sheathing worn off and cause a short. And that the locks, the seat, and the dome lights are all on the same circuit. I'll pull the seat out this week and see. So that's where I'll start, however, I think the headlight issue is a different thing all together.

I'm planning on doing "the big 3" (Replacing all of the main grounds with 0 gauge wire.) to the truck in the near future. Maybe that will fix it, or maybe I'll find the problem in the process.

I did check the headlight grounds, and they look fine.

Is there anything I can do to make the lights brighter? They are just so dim, and the high beams look almost as dim as the lows, they just seem to be aimed higher.

 

Check out this post for schematics:
Headlights go on and off while driving

 

Thanks. I'll have to check it out eventually. I'm out of town for the next few days, so I can't really do much with it.