Dim Headlight

Jul 25, 2003 9 Replies

Greetings all.



I have a 1997 Outback. The other night I noticed that the right headlight was very dim... barely glowing at all.



I replaced the bulb, but the new bulb is just as dim as the old one.



Any ideas what the problem might be? And advice on how to fix it myself?



THANKS! : )


Check the ground for that lamp. Happened to me on a Toy Pick-up once... Bill

Hmmm...the ground, the ground... um... I reckon that's one of the three wires that connects to the bulb, right? Any idea which one, and where it should be grounded?

Hmmm...the ground, the ground... um... I reckon that's one of the three wires that connects to the bulb, right? Any idea which one, and where it should be grounded?

To complicate things even further, Subaru headlights run on a switched-ground format. Looking at your headlight connector the power flows in through the center wire/pin, through both filaments, and out the two side wires/pins. The relays deep in the dash then switch one filament or the other to ground, thus creating the circuit. So, assuming a new bulb didn't fix things, there isn't really anything you as an average Joe can do to fix this. My guess is a flaky relay in the ground-switching system. IOW, it's dealer time.

Why not clean them all then?

-DanD

Thanks, Ned.

Just out of curiosity, why would they use something like this? Isn't it just as well to use a single ground?

This is not totally bizzare, I've seen the same headlight wiring on some older Datsun's (PL-510's in particular).

What is really odd is the way FHI chose to wire the dash lighting: Basically, the "ground" is a constant +12V and the "hot" varies through

0V, +3V, +6V, +9V, and +12V, effectively giving 12V, 9V, 6V, 3V, 0V to the gauge lights, which progressively dims the dash lighting. Makes it real tough to get aftermarket gauges that share a common ground between the sending unit & gauge lighting to work properly... As to why they did it this way, who knows?

Brent.

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