I was driving home tonight (friday) through a section with no street lights. I noticed real fast that I hit a small bump in the road and my headlights kinda blinked real fast. They didn't go off completely, but just dimmed a little, enough to notice obviously. I notice it a couple of times every time I drive at night if the section of road isn't really well lit. Anybody know what coupld be causing this. Could it be a loose battery terminal, or just something with the headlights. I have silvania silverstar headlights if that makes a diff.

 

I'd have a good look at all of the grounds in the engine bay as well as the battery terminals. Also, maybe have a look at the bulbs to make sure that something isn't wrong with the filaments. Another place to look would be in the fuse/relay center under the hood. Make sure that the relays and fuses for the headlights are in tight.

When I get back up to my laptop, I'll have a look at the ground locations for the headlights to help you narrow it down.

*EDIT* - in the headlight schematic, it looks like G200 & G201 are used... They are both located pretty high up under the dash on the driver's side. Pretty much behind the instrument cluster... These should not be your problem.

But it could be a relay starting to flake out, or simply a loose connection somewhere in the wiring harness...

 

Aren't there a couple of ground wires in the headlight harness near the core supports....people use them for the "quad headlight" conversion...I think they are "yellow" and screw into the core about halfway down below the headlights in the engine bay side of the core support...

 

They go into the main front harness in the engine bay. I just took a look at some more schematics and one of them made reference to G102. But this ground is also used on the DRL relay, Low Beam relay, Fuel Pump relay, Starter relay, Windshield Washer Pump, Rear Window Washer Pump Motor, the heated oxygen sensors and a few other things... I could not find out where this ground was located, but it should be somewhere near the underhood fuse block.

 

Found this pic on my GM Service DVD:

RH core support locations for some grounds:



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Thanks. I'll go outside today and check the fuses and relays, make sure everything snug. I check out those grounds too sometime. I want to get a chiltons book off of ebay for my blazer. I had one for my last car and it helped me figure things out big time. What book do you recommend? Chilton's or Haynes?

 

They both have their strengths and weaknesses. If I were to buy one, I would get the factory service manual from GM. You can purchase them at HelmInc.com, but they are pretty pricey...