Weird light question???

[gavinmosher]

84 chevy stepside the brake lights work and blinkers all work until you turn the headlights on then the blinkers don't work and the brake lights don't work and finally the right driver light doesn't work anyone have any ideas why?
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[Rifter_Chevy]

check the grounds, both under the dash and on the tail lights themselves.

[babyJay]

Buy a good ground strap kit, and ground the heck out of everything.

[Keith Seymore]

Ditto.

I used to paint the taillight brackets every spring and clean up the attaching bolts, using stainless nuts and washers (rather than the original star washers). I never could figure out why my lights didn't work - until I realized I was totally killing the ground circuit by doing so.

I ran a separate ground from the bulb socket, down the taillight harness and directly to a clean spot on the frame; no more problems after that.

K

[James McClure]

As a general rule of thumb, garnered from years of expirence, the weirder an electrical problem is and the more systems it affects at the most weird times the more the issue will be a ground failure someplace. The reason is simple. B+ goes to one thing at a time in seperate circuts. Grounds are ganged to serve a group of loads. EG, at the tail lights there are 3 B+ circuts but only 1 ground. Thats the same at all 4 corners. IP clusters are the worst especially with guages and courtesy lighs are wired backwards from everything else with power going to the lamp first and ground supplied later. Jim