Improving the quad headlights

[vlad13]

1983 Subaru coupe, 4 square lights. This information seems to apply to brumby as well.


I was fixing things on my car today when I remembered that long time ago I measured the voltage the headlights get and it was quite low. So I measured it again and the headlights on low beam get about 10.6 V, about 1.6 V below the battery.That seemed a pretty high drop, so I started measuring some more. I found that the ground wire that connects the negative battey terminal to the car body has between 0.2V drop at idle and 0.4V with lights on. That seemed high, so I made a strap (from amp wire) between the engine head, opposed to where the other negative wire goes, to the ignition coil mounting bracket. There might be better solutions but my battery terminals are non standard so I can't change them without a new battery.

That reduced the voltage drop on the battery wire to 0.05V. Now back to the headlights.

The voltage drop was on the ground wire, which I found unusual, so I had a look on the wiring loom diagram in the manual and decided to ground it closer to the battery. I did this by soldering a wire on the sealed beam lug closest to the driver's side (the beam lug is marked with an L). Then I earthed this on what seemed to be a horn mount a long time ago. The headlights now get almost battery voltage, and connecting and disconnecting the additional ground wire with the lights on makes a noticeable difference in brightness.

Hope this helps.

[Gannon]

Good find, very helpful.

I did a similar thing, but i rewired them completely... Independant Headlight Relay Conversion