Headlight wiring questions.....

Still working through the bugs on a 96 that we picked up about a month ago. Next on the list.....headlights.

The PO swapped in aftermarket headlights, but something isn't right. I've included photos below.

They work......but the Hi-beam switch turns them completely off (if you push the selector, they go dark). And.....when they are in normal / low beam mode......it appears that one of the lights is in fact on high-beams. (Photo #2)

Before i dig into this, I thought I'd check:

1. Is anyone familiar with the upgrade and how the PO got his "wires crossed"?? (no pun intended)

2. Anyone recognize the brand or have the wiring instructions?

Photos 3-6 are of the wiring on the left / right. As you can see......several wires (2 blue on each side and 1 red on each side) are not even connected. Any help much appreciated. Thanks!!!



Thanks again - Chris

 

This might help!

 

So I've checked the wiring - and good / bad news......we've fixed 1/2 problems. I now have legit low beams (the PO had swapped 1 of the two wires on the hi / low beam plug). So unlike the photo # 2 above....both light will illuminate correctly in low beam mode. But....I still have an issue when switching to hi beams. I had thought they go completely out.....but they actually produce a little (very little) light. I'm thinking the switch is okay.....because whether I push it (to lock in the high beams) or pull it (as if you were quickly flashing someone)........the lights go out (or almost out). It is barely noticeable in the daytime......but you can see partially lit leds in each of the 2 headlights. From what I can find in the manual and online......there is no separate fuse for hi-beams......and like I mentioned.....the switch *seems* to be functioning.....otherwise I'd expect to see no change.

As Wulf mentioned above......I verified the ground is in the correct location.....and I can measure 12+ volts when "low beams" is selected with the switch - and those work fine. But when the switch is moved to high beams.....I have no voltage (actually a slight negative voltage??) on the high beam pin. AND.....I still have the full 12+ volts on the low beam pin.....but no lights at all (or barely noticeable).....not even low beams.

Not sure if that makes sense.....but I need some wiring gurus to talk me through this. I have a volt meter.....and I'm familiar with how to use it......I'm just not sure how these trucks are wired. Here's my questions, hopefully condensed where it makes sense:

1. When high beams are selected with the switch.......should the low beam pin (top of the connector) switch off and the 12+ volts go to the high beam pin?? Or is voltage sent to BOTH pins?? And what controls where the voltage is sent???

2. Since I'm getting no voltage at the high beam pin.....is there a fuse, relay, etc that I should be looking at??? Or a broken wire that is somewhere between the connector and the switch??

Again.....I suspect the switch is operating......because I do see a change whenever it's toggled - I just have no high beams.

Hope that makes sense - thanks so much for any help!!

 

Maybe this one:

$79 SPL 105W Brightest 5x7 7x6 Projector Led Headlights Sealed Beam H4 Plug H6054 H5054 with DRL Compatible with Jeep Wrangler YJ Cherokee XJ Ford Chevy GMC Toyota etc(Black Pair)

https://www.amazon.com/SPL-Brightes...6+h4+headlight+housing,automotive,259&sr=1-12

 

I'm not 100% sure about the wiring on first gen Tacos, but I am going to go out on a limb and guess the lights are negatively switched. I haven't done a conversion on my truck but did help a friend who was having this exact issue with LED headlights on his FJ60, it seemed like we could rearrange cables in every possible configuration but no matter what they wouldn't function correctly on both high and low beam. The issue ended up being that the OE lights switch on the negative, whereas the LED bulbs are made to switch on the positive. This can be remedied with some relays, either ones you get yourself from the parts store or one that I'll link below (the link is what we used and it worked like magic once installed) and also some video/documentation that helped me figure out the fix before I pulled the trigger on parts. Again, I don't know for sure that this will work on the Tacoma but it worked great on the FJ. I do not recall if the dash high-beam indicator was working or not after the fix.

Info:
DIY with accumulated parts, the pre-wired kit from Amazon will have the same effect, but this guy gives a decent explanation of the issue and resolution (https://www.youtube.com/watch?v=iB0JHkLyFHg , https://www.youtube.com/watch?v=qZoP1pTa_ag)

Ramblings on wiring (https://forum.ih8mud.com/threads/led-headlights-for-fj60-and-fj62-landcruisers.907201/)

Pre-wired relay set I used:
We used this on a FJ60, but reviews indicate it should work for your Tacoma also (

$22 True Mods H6054 H4 LED Headlight Wiring Harness [Negative Switched Conversion] [Fused] Universal H4 Head Light Relay Harness Kit for 9003 H5054 H6054LL 6014 H6024 6052 6053 Subaru Toyota Jeep Headlamp

https://www.amazon.com/gp/product/B07M6W1PMK?ie=UTF8)

 

Super helpful - thanks to both of you. I do think the kit (if not the exact same) appears to be very similar to the one linked above in the Amazon post.....so thank you for that. And - FatBilliam.....I definitely think you're on the right track - I should have thought of that. I have an old CJ7 that I upgraded the lights on (early CJ's had TERRIBLE stock lights). I used a relay kit for it that uses power directly from the battery like the link you provided. The previous owner of this Taco skipped any relay install - the H4 sockets plug directly into the vehicle harness. So, as you say, if the factory switches on the negative, I'm guessing that's the issue. Anyway - I'll continue to research, but I suspect you're onto something. I'll report back.

Thanks again for the help.....

 

Still scratching my head on this. I did order the Amazon harness.....but unfortunately that didn't solve it.

To recap - I have working low beams (12v at the top pin) but when I toggle the selector to high beams....the lights go out (or almost out). The voltage continues to read 12v at the top pin......but then 4.xx volts on the ground pin. Like you mentioned above.....I'm thinking it may be a "negatively switched" circuit. BUT - if this was the case.......wouldn't there be a constant 12v supply to one of the pins whenever the key is on? Then, based on the switch selector......either a loop for the low beam circuit or high beam circuit??

The documentation with the relay kit mentioned this (as step 1). "Check to make sure your vehicle is negatively switched by turning the key on and verifying you have 12v at the factory connector". Mine doesn't - and I'm not sure if it's supposed to or not. I did install the harness briefly just to see.....and it didn't solve the issue....so I can always return it.

Sorry - I know I'm probably making this more complicated. I feel like it's something with the wiring. The switch at the column I'm guessing is okay.....since it will toggle and change the voltage.....it's just not correct.

The above videos has (2) relays on each side.....for a total of 4. Basically 2 for the low beams (r and l), and 2 for the high beams (r and l). The harness I ordered only has 2 total.....one for each side. Seems like a lot, but maybe that is necessary......and what is needed to work with the factory wiring. Anyway......before I go piecing something together with parts......I thought I'd check back. Any other ideas?? Or advice / info??

Thanks!

 

If your instructions are not for Toyota`s but just general that might be part of your problem.

Our headlights work by the headlight switch completing the circuit to ground.

Unless the last owner changed things the headlight circuit is not switched power! Not sure where you saw the ignition switch needed to be on.

Pin #3 should always have battery voltage !!

You need to check both sides of the headlight switch if the high beam position is not completing the circuit to ground

Someplace you have a poor connection or miss wired . You need to go wire by wire for what is not correct.

I wish I was close I would have this figured out.

I lost my 96 EWD when my computer crashed someone has to have a copy I downloaded it from here.

Good luck!!

 

Headlight high/low beam is switched on the ground side which is different from most vehicles.

 

IIRC the video uses 4 because he puts 2 on each side and hooks into both factory headlight plugs, the Amazon kit just uses one of the factory plugs to switch high and low, thus only needing half as many relays. Did you try swapping around those high and low pins that the PO had switched around? Just wondering if it may need some reordering of the wires. Other than that, I'm with @Bivouac it could just be a bad run of wire somewhere and you may have to follow every wire from end to end to verify they're doing what they should be...

 

Thanks for posting this !!

 

I wish I were a little more adept at reading wiring diagrams. Thanks for everyone being patient with me on this. Here's where I am currently - using the diagram below to explain:



PIN #1:

I'm calling this "low beams". It has zero volts with key off. It has zero volts with key in the "ON" position. When head lights are turned on - it has 12+ volts, and low beam lights illuminate as they should. When the switch is toggled to high beams, pin #1 STILL HAS 12+volts.

PIN #2:

I'm calling this "high beams". It has minimal / nominal voltage......regardless of the key......and regardless of where the selector is set (hi / low beams).

PIN #3:

I'm calling this "ground". It measures grounded to the negative battery terminal, chassis, etc. Zero (or very low voltage).....UNLESS the high beam is selected......at which point it reads 4.xx volts.

Couple other notes: Both sides are the same in the pin / ground readings. Low beams work, but when switched to high beams......lights go almost all the way out (very faint.....so dim it's hard to recognize in the daytime).

FATBILLIAM - you're correct about the "only using 1 factory plug" on the relay kit I have (the one I ran on my Jeep was the same way). But - it didn't solve the issue. AND.....I think you could be correct with the pins being somehow swapped / the wires needing "re-ordering"

So here's my question (which I'm embarrassed that I can't answer with the wiring diagram)......but....

Can someone explain (using the #1,2, 3 pins in my diagram) when there *should* be 12v in the various modes - Key on / off......high beam / low beam......ground to chassis.....etc??

ie: Low beams, Pin 1 (12v) Pin 2 (0) Pin 3 (ground)........High beams (Pin 1 ?) Pin 2 (?)....etc...etc??

EDIT: I guess I'm wondering if when high beams are selected, it should switch off the 12V at pin #1 and transfer to Pin #2 - correct??

Thanks again guys, and sorry I haven't been able to answer these questions with all the info you've given me above. And thanks DM93 for the diagram.....It makes more sense, but I'm still scratching my head unfortunately.

 

Using your numbers, the negatively switched Toyota wiring is going to be something like this: PIN 1 - Always has 12V+ when lights are on (high and low), PIN 2 - Ground for your high beams, PIN 3 - Ground for your low beams
Pic ref. https://www.toyotanation.com/threads/led-headlights-only-throw-high-beam-no-low-beam.1550322/


Assuming you have switched the black and yellow cables from how they are shown in the OP, I'm not sure why the relay wouldn't be working unless there is a bad ground somewhere.