Anthony Liardo

Car: 1993 Civic DX w D16z6 in it

So I had some electrical problems in 2017 and I think it’s what destroyed my distributor and ecu, but it may have been from using those loud horns (the ones everyone puts on a Subaru, can’t think of the name) AND/OR the problem I’m having now.

So I got the car with Hondata but I swapped in my p28 and everything ran fine besides the ecu/o2 sensor wiring being different. I read on here that it goes to a safe tune and I ran that for years and didn’t think much of it. Always told myself I’d go back to Hondata when I turbo it and it’ll be set up for me on the wiring. 3 months ago died while in neutral and wouldn’t start. Fuse 15 (I believe it was 15, whatever the ecu one is) blew and I replaced it and the car started and died a second later. Fuse blew again. Found out it was the O2 sensor because I disconnected the sensor and it ran. So I took the time to put a stock O2 sensor in and wire it stock. Finally got no check engine light but I noticed on my first drive that my battery light when on when I coasted, as in went in neutral after accelerating. Any bit of throttle would turn it off and it would turn on and off with no pattern. I drove it daily until last week and discovered some things: 1. if I disconnect the vehicle speed sensor, it doesn’t go on, but I get a check engine light for VSS after 10-15 minutes of driving. 2. If I have anything electrical on like headlights or ac, it never goes on, even driving 4 hours straight. 3. If I ever give it a tiny bit of throttle when the light is on, the battery light goes off. 4. I’ve measured voltage while the light was on and I believe it was normal battery voltage (12.6ish, def not 14+).
My car wouldn’t start last week and the first time I tried, it started like normal but never fully got to normal idle and died. I thought I didn’t hold the key long enough so I tried again and it died faster. Then it just started cranking with no start. Towed it home and realized the fuel pump wasn’t priming. Measured voltage and it’s getting voltage at the pump. So I believe this electrical problem/battery light issue might’ve contributed to or caused this part to die because it was a genuine Walbro 190 lph fuel pump that I put in in 2017 when I could not find out what was causing my car not to start.

So I want to get to the root cause of why my battery light goes on at idle when the VSS is plugged in and no other major electronics are on. (I replaced VSS because my speedometer jumped a little every now and then and I thought that was the electrical issue but there was no corrosion and I cleaned it perfectly.) Again, it goes off as soon as I give any throttle. I checked continuity from blue wire on alternator plug all the way to D9 pin on ecu, as well as white/yellow wire on alternator all the way to ecu A16 pin. White/blue (dash battery light) wire goes to driver side harness plug and I’m sure it goes to the dash because that’s how the light comes on, right? What voltage does the ignition black/yellow wire get? Battery voltage whenever key is turned to on?

Im going to ride around (when my fuel pump gets in and I get the car running again) with wires going from the battery to a voltmeter in cabin so I can see what the battery voltage does as the light comes on/off. For now, can somebody please explain to me like a kid how the alternator voltage regulator and “fr” and “c” and “l” work with the ecu and eld and what causes the battery light to go on and what might be going on? My ELD is correctly wired to the ecu as well (well the wire is in the pin and I’d bet it’s in the engine bay fuse box harness because there are no loose wires there). But yeah, please explain how they all work together and what causes the light to go on and what would cause it to go on at idle with no electronics on while never going on if headlights or ac is on.

thanks