Wiring diagram can be found here,
https://alavigne.net/Motorsports/Fea...s/S2000/DRL/#_

It's been a couple years sense I've diagnosed an electrical circuit. However I've taken the electrical portion of an automotive degree; A if it matters. My left(driver side) low beam stopped working. Both 20A fuses and relays check out. Swapped both around and the right head light still worked. Clearly the 100A fuse is also good.

What I find intriguing is that with the power on and the headlight switch off, the 20A fuse after relay #2 will only draw 20-50 mV. With the headlight switch on it will draw normal V. The other 20A fuse draws normal V with or without the switch on. Is this normal?

I have swapped out the ballast with a used unit with no luck. However I didn't check to see if it worked and I didn't switch bulbs ether due to time. The initial symptom was that the headlight would turn on normal for 5-10 seconds, then the color would turn from white to purple, start to flutter and would eventually go out completely. Now it won't even turn on. I just thought ballast without diagnosing.

I'm tired so I'm sure I'm missing something. It's clear that I need to switch bulbs and possibly ballasts but right now the V from that one fuse has me thinking. I'll get back to it tomorrow. Any thoughts?

 

Check the ground, it could be that it's not grounded. I'm not sure.

^^^ I'm pretty sure the ballast is relayed and the 20A fuse is for the constant on with the interior headlight lever being the switch. So it should be normal to have the other 20A fuse constantly drawing 12v. Again I'm not 100% sure, I'm just pretty sure. Haha

Edit: Had the helms manual as a .pdf on my computer and spent the last hour trying to convert it and here is what I got.

 

The term "draw" is normally used for current; are you measuring voltage or current? I'll assume voltage, in which case your measurements seem correct.

No, there should be no power on that fuse unless the headlight switch is on. The low beams are permanently connected to ground, so if you have +12 on the fuse (and thus the low beam too) then the low beam must be on. If it's not on, either you have some totally screwy wiring or you are not measuring something correctly.

Also, if you truly have +12 on the fuse from relay 1, it will feed through both high beam filaments and you should see significantly more than 20-50 mv on the driver's side. You'll see 4-6 volts if the low beam is good (and it will flicker trying to start), or you'll see +12v if the low beam is bad or disconnected or has a bad ground.