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ChevyMan
08-05-2009, 04:26 PM
My '76 Chevy has run into headlight trouble. They are the four-lamp system. On HIGH beam, all lights comes on. On LOW beam, only the RIGHT OUT BOARD comes on.

Fact: One switch control all headlamps, parking lamps, etc. All parking lamps lights.

Any opinions welcome. State statute require headlamps be operational or car will not pass annual State Safety Check. No pass, car grounded.

Larry

chiph
08-05-2009, 06:44 PM
Left low-beam filament is burned out.

The '81 Fairmont had quad headlamps, and I had both low beams burn out at the exact same time. I spent most of a day rationalizing why it couldn't have been the bulbs and was obviously a wiring problem.

It was the bulbs.

Chip H.

ChevyMan
08-05-2009, 09:37 PM
I don't quite get what you mean.In a 4-light system, the HIGH sealed beam lamps comes on when you activate the switch in the driver's compartment, and the LOW beams comes on when it is switched off. One of the lamps that failed to light when I turned on the LOW beam is a brand new lamp Installed yesterday.
When on "low beam", only the 2 in-board lamps should light but they did not light, ONLY the RIGHT outboard lamp came on. Go figure.

Larry

Ken
08-06-2009, 06:13 AM
I don't quite get what you mean.In a 4-light system, the HIGH sealed beam lamps comes on when you activate the switch in the driver's compartment, and the LOW beams comes on when it is switched off. One of the lamps that failed to light when I turned on the LOW beam is a brand new lamp Installed yesterday.
When on "low beam", only the 2 in-board lamps should light but they did not light, ONLY the RIGHT outboard lamp came on. Go figure.

Larry

I don't know the system, Larry but one thing that can cause that type of problem is a poor earth or missing earth wire. I've had some funnies due to poor earth connections, indicator lights coming on when it should have been the sidelights, brake lights blinking in time with indicators - that sort of thing. Another, less likely option is that a plug could have been mis-orientated when fitting the new light.

Ken.

chiph
08-06-2009, 09:35 AM
Ken has a good point. There are likely separate left/right grounding points on the fenders.

ChevyMan
08-06-2009, 06:19 PM
Excuse this Dummie who made a big boo boo regarding the lamps. I got the positions of the high and the low beams mixed up. I thought the INBOARD LAMPS were the LOW beam and vise versa. My bad.! Twenty lashes for me!!

Larry