[1980 TA]

I just picked up a 1971 Lemans sport and am trying to get it ready for inspection. The headlights work fine on low. When I flip to high, the left side has neither bulb illuminated and both on the right. The previous owner said he replaced the bulbs a short time ago and they don't look burnt.

What is throwing me is that the left side low went out as I would have assumed it would have stayed on.

I'm not familiar with the lighting circuit at all and would appreciate any pointers on trouble shooting. Once I get this fixed, it should pass inspection.

[Scarebird]

Check and clean the grounds at the core support first - easy, free and the source of many ills.

[tjs72lemans]

Also, try to wiggle or unplug and plug connector to lights back in.

[Goatracer1]

It sounds like you are losing power to the left when high beam is on.. The low beam bulb has two filaments. One for high and one for low. When you turned on the high beams you turned OFF the low beam filament in the bulb therefore no light. If you have a voltmeter (or at least a test light) work your way back from the light until you find the problem.

[1980 TA]

Thanks for the help everyone. I thought the low beam might have two filaments but wasn't sure. I do have a volt meter and test light, I just wasn't sure how it was all supposed to work together.

[OG68]

This is a rough sketch I drew up when rewiring my headlights.
Note the factory high beam splice on the left side.

During your meter check, if you have no power to the high beams on the left side, but hot on the right, check this splice. Unroll the black tape from the left (Driver) headlight socket to where the harness passes through the core support.

[OG68]

Additional photo. Green/Black tracer wires are the high beam circuit.

[1980 TA]

OG68 that helps out tremendously. Thank you.

[1980 TA]

Ended up being burnt out high filament on the low beam and burnt out high beam. Sometimes its nice to get the easy fixes.