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Dim Passenger Headlight


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Hey guys. 90 Loyale 1.8 4wd. My passenger headlight went dim after a massive snowstorm last year and hasn't been bright since. The driver is nice and bright, and all other lights are working properly. I tried wiggling the bulb connector with no change. Went ahead and replaced the connector with a known good one. No change. Any ideas? I understand these don't use your typical ground wire. I tried adding a ground to the solid red and it just kept the headlights on dim with the switch off. My understanding is red/blk is low beam, red/white hi beam, so I assumed the red was ground wire. Electrical isn't my fortay, and faulty ground seems to be the most common explanation. Also, I understand these use a seperate relay for the right and left side lights, but I can't find anything on their location. Fuse for right and left are good.

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Relays are round looking canisters above the driver’s feet. You’ll need to remove the kick panel to access them. 

Any damage to the wiring on that side of the vehicle, or wiring added in that general area?

Have you tried swapping the globes from left to right? 

Cheers 

Bennie

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Have you tried a new bulb? Or just switch the bulbs from one side to the other?

Generally speaking, a dim light is usually in the ground side of the circuit (far more likely to have resistance without a break on that side of the circuit). But if you ran a ground wire to the low-beam wire and it was still dim, that's not your issue. After the bulb, the thing to do is to put a Multimeter between the bulb power wire and battery negative, and check your voltage. That will confirm which side of the circuit is the problem.

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check your fuses i had that problem and couldent figure out why one was dim and the other was good then i lost my tail lights and while trying to fix that i found a burnt fuse i thought was for the rear but it was the headlight dont ask me why it was still getting power but it was new fuse nice bright headlights i think theres a bit of a back feed from one headlight to the other

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All fuses were good. I did find a body ground just below the harness. Tried cleaning with a wirebrush and no change. So I started pulling back the wiring protector on the entire passenger harness almost all the way back to the driver side. No visual damage and no change going down the wiring bending to see if it was an internal short. I finally got tired of chasing it and just wired it into the driver light harness with some quality heat shrink crimp connectors. Back to nice and bright. 

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And im pretty sure there is alot of backfeed between them. While bulb swapping and checking for loose connections, I noticed the passenger bulb wouldn't come on at all with the driver side removed. Either the passenger side was wired directly into the driver, or a previous owner had made it into a single circuit like christmas lights. Either way, it's fully functional again and my next step is upgrading to led bulbs. Wattage is lower draw on the electrical and I might actually be able to see more than 5 feet in front of me. Lol.

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The stock headlights should not be that bad.  Not as good as for real projector type, but way better than the old sealed beams.   If the reflectors are rusty, no bulb you put in them will fix it.  I have seen some get rusty, if moisture got into them.  

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51 minutes ago, DaveT said:

The stock headlights should not be that bad.  Not as good as for real projector type, but way better than the old sealed beams.   If the reflectors are rusty, no bulb you put in them will fix it.  I have seen some get rusty, if moisture got into them.  

They aren't horrible as some i've had in my day, but there is definitely much left to be desired. As I use it alot for offroad and winter weather, the brighter the better. Also hooking up some waterproof led fog/driving lights to assist.

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The symptoms described mean that either the Passenger side HL fuse is blown, or the Pass side relay is out.

This is confirmed by the fact that the pass side goes out entirely when the driver side is disconnected.

Since you checked fuses, I suggest checking the relay.  It is under the dash, left of column, black connector, with a BW, BY, B, and smaller Black wires.

BW is power from battery, BY is power out to Headlight fuse 8. Large B (or other color in some years) is Ig. switched power, and the small black is ground.

Hope this helps.

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Quote

 

1991 Loyale. Try swapping out the relays under the dash. There are three relay canisters that are same part #.  I was working on a heater fan problem and checking under dash for heater relay.  So I swapped them out [same part#] to check heater motor. Anyway, one of the swaps gave similar right headlight behavior.

Edited by rickyhils
added "relay"
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  • 1 year later...

I just now found this thread. 98 Forester, left side went dim. Replaced connector, nuthin' changed. Swapped relays, left side worked, right side went dim. Just now got a new relay, everything is fine.

Connector was degraded somewhat, probably brought the relay to its end. There is definitely backfeed between the right and left.

Edited by Daddybob
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