headlight problem

[joel]

I just recently did some work on my 86 silverado including new dimmer switch, new headlight switch and now when i run the brights, after a few mins, they will flicker on and off with no discernable pattern.  The low beams work just fine.  All thoughts and advice appreciated. Thank goodness for this wonderful place!

[78 Chevyrado]

Sounds like a bad connection somewhere.  I'd start checking everything that got unhooked and check there, maybe the connectors are hooked up good but a tab inside is screwy.

Sounds like it gets worse after whatever it is heats up.  Resistance makes heat and heat makes more resistance.

[ssapach]

I had this exact problem with my 1986.  It has the 4 headlight setup and I replaced the sealed beams with some fancy new housings and Sylvannia bulbs.  Before that I had also replaced the headlight on/off switch because my dimmer was worn and would not work properly for the dash lighting.

After I put the new headlights in, they would flicker randomly with the high beams on.  With high beams on it was all 4 headlights on at once.

The problem I was having was too much current through the dimmer switch.  All I did was put a relay under the hood and cut the current draw through the switch by about half the amperage and suddenly I have no more headlight issues with high beams. 

I also put the high beams powered off the relay, in case of any problems I should hope to not lose my low beams this way.

Hope this helps!

[firefighter]

I do know for sure if the dimmer switch is not hooked into the circuit, the headlights won't work at all.
That said, a flaky connection may allow the lights to flicker under a heavier load.
I also agree that it is possibly a loose connection issue with something you just worked on.
I'd disconnect each connection, inspect for any possible corrosion, smear the terminals with dielectric grease and firmly plug back in.
I'm guessing your issue will be gone.

[joel]

Great ideas!  Thanks and I'll check my connections and see if I have a drop while I'm at it.  Let y'all know how it goes after the weekend I'm sure.  Dependent on the jumpy TN weather of course.

[bd]

3 Questions:  1) Why did you replace the headlamp switch?  2) Are you running sealed beams or capsules with replaceable bulbs?  3) Did you make any changes to your headlamp wiring?  If the symptoms persist after you check/clean/tighten your connections, replace the headlamp switch again.  The headlamp switch contains a non-servicable circuit breaker.  Random cycling of the lights is a common problem for a weak, or under-engineered, or over-stressed breaker.  Try a different brand headlamp switch, or as mentioned, add a relay.

[joel]

bd, I had no rear parking lights. couldn't figure out what was going on, so as i usually do, started replacing parts. I knew there was an onboard breaker in the switch, and i already thought if the problem was still there it could have got the new switch and its an off brand switch too.  I still have the stock light setup with sealed beams.  all lights burn great with no problem except the high beams.  I just have to get the time to look around again.  The bad thing is this is my daily driver so its hard to pull it off the road. I don't drive far so I'm just waiting for decent weather to get out there on it .  My garage is the old Tennessee tool shed. HA!

[bd]

I know what you mean about the daily driver.  I have similar circumstances.  I'm sure you've already thought of this, but if you still have the old headlamp switch, plug it back in and see if your highbeam problem goes away.  Might save you some time(?).  IMO, the relay idea would be a last resort for a factory build.

BTW:  do your rear park lights work now?

[joel]

yeah everything works great except the highs.  Before everything worked great except the tails.

[bd]

  ...go figure....