2013 FR-S wiring issue
 

Headlights aren't right, (very dim Lows, and almost no Hi beam) and it doesn't seem to be the fault of the aftermarket headlights.
Tested hi and low on both sides, at the connectors, w/ headlights unplugged.

RH side;
with lights on low: low beam wire shows 12V; high beam shows 0.24.
Lights on high; low beam and high beam show about 12V.

LH side;
lights on low: low wire shows about 12V, high is about 0.24.
Lights on hi, low is 12V, high shows 0.12.

The wiring under the hood appears unmolested. I don't see any obvious damage / tampering under the dash, but can't see much. The headlight dust covers have holes hacked in the back which are taped up: don't know what used to be in there.

What to test next?
All suggestions welcome.
Many thanks;
Alan

Dunno but let me know if you need the body harness. I probably have one laying around.

Other than tracing the wires.. :shrug:

What type of lights are they?

If he's measuring it at the car harness it shouldn't matter... unless there are headlights for these cars with dumb wiring?

God only knows! Is relevant info to know.

Follow up question, OP, are your aftermarket headlights HID?


humfrz

Replies appreciated.
I think the headlights are Spec-D's. They have LED elements in them now. I'll try better bulbs, if I can figure out the wiring.
And yes, Dave-ROR, I may very well try to buy a harness off you, if I can't get this straightened out.
I wouldn't be surprised if the previous owner had HID's, but don't know for sure. The PO took decent care of the car, but was not a mechanical genius. And, the car looks like it got lightly stuffed into a grassy high spot, at one point. The fender liners are a bit chewed, and I picked some weeds outta there when I got it. But I don't see evidence of significant damage.
I'll keep tracing the faulty wire back as far as I can. But, the way the hi beam voltage drops when turned on makes me suspect a short, or a cross up somewhere.
All opinions welcome; I'll post the solution if I find it.
Many thanks, (and how do I, "thank" folks who reply?)
Alan
Central CA

It does not seem to be the fault of the headlights?

It does not SEEM to be the fault of the headlights???

Seems like those Spec Ds use a single hi-lo projector. All it needs is a 12V to power the light source and another 12V for the high beam solenoid. If you've got those, it doesn't seem to be the fault of the car.

Ok, there's more you could look into. Where are you testing for voltage? At the plug? Good, but where's your ground probe? On the ground terminal at the plug or on a separate ground point? a bad ground can make lights go dim, which is also why you don't test a high amp circuit like headlights with a multimeter: It seems like a good plan, but a multimeter doens't load the circuit thus will have a hard time picking up on bad splices/terminals/grounds. Use a test light with both ends at the headlight plug, look for it to be as bright as when it's testing at the battery terminals.

Also, those "LED elements" they've got right now, what are they? Aftermarket LED bulbs? Which bulbs? What are the headlights meant to use? Have you tried the original bulbs? Many aftermarket LED bulbs are PIECES OF JUNK and have the absolute worst light output when put into a housing meant for any other light source. Everything could be working as intended and you've just gone and borked it with junk light sources.

Recommendations on an LED H1 hi/lo combo "bulb"?

So, after I realized I'd written down the wiring diagram wrong, I see that I'm getting 12V to both high and low, correctly, for both sides, as far as the car's harness.

The headlights, (or rather, the PO) are at fault. AND the bulb's wrong. Sheesh. What I have is the + and - for the low beams, hooked up to the single light. Which is not a hi/lo combo. Inside the light I see empty spade lugs on the side of the socket where I guess both the high and low should ground. Wires for high beam go into the light assembly, but are not visible at socket.

So, I need to open up the light assembly, ground both hi and lo, and then install an H1 LED combo. Right? Off base on that? Missing anything?
Many thanks;
Alan

Just. stop.

Looking at your other post...

The two blue wires near the socket, that's your lo ground and lo power. Stick the ground back to the socket and install a halogen H1 in there and stick the power wire to it. If you're flipping the high beams on and off and you can hear a solenoid going clack clack inside the headlights, that's working fine. See diagram, you don't need a hi/lo bulb, there's a shade in the projector that flips down for high beams.

Restore the headlight to it's original setup. Install normal H1 bulbs, confirm operation and light output, that is your number one priority. Once you've got lights on the car, you'll have all the time in the world to pay too much money to some shady online retailer for some wonky LEDs that'll fail too soon. When dealing with bad things badly installed by bad people, you don't way to play around in the mess they made, go as far back towards stock as you can go. You probably don't have a set of stock headlights lying around, but at least you can ditch the shitty LEDs.

After you make about 10 posts a "thanks" button will appear at the bottom of peoples posts, you can punch it if you wish - ;)

Sorry, I can't help you with your headlights, my knowledge base ended with the sealed beam headlights - that had two prongs in the back of them that plugged into a socket with two slots. - :iono:


humfrz

Geez even the 3 prong variety is beyond your experience? What about negatively switched vs positively?

Yepper, I had a headlight burn out in my 1937 Chev PU, that was the last time I had a headlight burn out, so, that's where my hands-on knowledge ended - ;)

+ or - switched? Didn't much matter, back in the day, as long as one stopped the electrons from moving. I preferred positively switched - just made more sense to me. - :iono:

BTW, what's your age, there Dave-ROR?


humfrz

Youngin’ At 42