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No low beam but high beam works

22036 Views 4 Replies 2 Participants Last post by  shantz24
Having a problem with my girlfriends 2005 Equinox. Passenger side high beam works but low beam does not. Changed bulb 2x, no luck. Socket was cracked and 2 wires showed some corrosion, clipped wires and bought a new socket and installed it. Still same problem. Used a volt meter and can not find a difference between passenger and driver side either with lights on or off. RH/LH Headlamp fuses under the hood are OK. I am at a loss as to what it can be.

Can anyone tell me how these dual filament bulbs work? Seems like what appears to be the ground for low beam becomes energized when the high beams are on. Are the 3 wires wired in some sort of phases that switch? I had originally thought that one would always be ground and the others would be hot. I guess thats not it?

Any help would be greatly appreciated. Don't really want to pay someone $70/hour to fix this.
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Just a guess but check the relays. My Saturn Vue uses a relay to switch the grounds. Those vehicles are on the same platform so maybe it will apply to your problem.
Keep us posted
I had checked the fuse box under the hood and only saw the two fuses for the headlamps, no relays. There was the driving lamp relay and fog lamp relay. Might it be the driving lamp one? I am not real sure what lights are the driving lamps on it.

On the center console there is the Headlamp relay but it doesn't look like it would control Left/Right independently.

I'll be the first to admin I don't know much about these cars, so any info is great. Thanks for the quick response fireman.
shantz24 said:
I had checked the fuse box under the hood and only saw the two fuses for the headlamps, no relays. There was the driving lamp relay and fog lamp relay. Might it be the driving lamp one? I am not real sure what lights are the driving lamps on it.

On the center console there is the Headlamp relay but it doesn't look like it would control Left/Right independently.

I'll be the first to admin I don't know much about these cars, so any info is great. Thanks for the quick response fireman.
Most light relays are "double through" Meaning they have a output post for 2 lights. A four prong relay is a single through and a five prong relay is a double through.
Was not able to determine exact cause of it but after talking to a local mechanic that has seen this happen in other cars we "fixed" it. Mechanic suggested the fix he uses......ran a jumper from the driver side to the passenger side. Everything works just fine. Mechanic said he traced the cause to a ground short or defect in the wiring harness but for the price of a harness this works.
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