I just replaced my sealed beam headlights with Holley LEDs in a all-four-low, all-four-high configuration (thread). There's some stuff that confused me about this whole thing that I want to write down here before I forget. I hope it helps somebody else, or, most likely, myself when I need to make a change to this in six months and don't understand it anymore.
Basically, slcfj62 has said everything you need to understand how the headlights on these trucks work in one thread or another, but I was confused about a few things when I started doing this:
* fnpierce's incredibly helpful thread about upgrading to some JW Speaker lights doesn't add any new relays, it just swaps some pins around.
* more recently, vankho posted this thread about using Holley RetroBright with the Holley H840 harness, which does have include new relays to deal with the switched grounds
So do you need to find a place to mount the new relays or not? The answer is it depends how you want your headlights to work.
On the factory setup, there's four headlamps. I'm going to call them the 'outside' lamps and the 'inside' pairs to avoid saying high beam since that will get confusing, but in the stock setup, the inner pair light up only on high beams. The outer sealed beams have three pins: ground, low beam, high beam. There are two filaments inside (or whatever lights up in there, gas envelopes, I don't know, it's easy to see though if you unook the inner lamps and switch between high and low on the outers). The inner units only have two pins, and only have the single filament that's lit in high beam mode. To summarize
* FACTORY OFF: Everything's off
* FACTORY LOW BEAM: Outer pair low beam lit, inner pair off
* FACTORY HIGH BEAM: Outer pair LOW + HIGH lit, inner pair HIGH lit.
When the FJ62 was initially designed in Japan, the engineers inserted a flaw in it, because perfect things are an offense against God. The engineers decided the flaw would be inserted in the design of the headlight electrics, which as a result, are completely deranged.
The outer pair of lights are driven by three pin H4-style connectors. These connectors, looking into the connector as if you were standing in front of the truck looking towards the grille (so the driver lights on your right side, passenger lights are on your left side) have the following pin arrangement:
LOW BEAM GROUND +12V THATS ON WHENEVER THE HEADLIGHTS ARE ON
HIGH BEAM GROUND
For the sealed beam lights, this is ok, they don't care about polarity. The ground pins are left floating when that particular light isn't supposed to be on.
The inner lamps connector, the ones that are only used for high beams, has only two pins:
HIGH BEAM GROUND +12V THATS ON WHENEVER THE HEADLIGHTS ARE ON
A lot of posts in here refer to the problem being that the system was designed with switched grounds. I get why people say that now but it was a bit confusing to me when I was trying to figure this out. The problem isn't really that the grounds are being switched. The LEDs will work fine if you switch the grounds. It's really that any replacement LED headlamp is going to only have one ground, and you can't wire it backwards, because the LEDs only work one way. So you can connect either of the switched grounds to the headlamp, but it's going to light whatever led in the headlamp has +12V on it when you do.
The clever dudes that fnpierce talked to noticed something important about the way the factory harness is set up though: Everyone says it has a 'hot common' and a 'switched ground, but in reality, the common is switched as well. When the lights are off, there's no power at the +12V pin in either of the connectors. This really confused me before I took it apart and tested it. I assumed "hot common" just meant there was a 12V supply wire that was energized whenever the car was on. No. I'm assuming this is so the lights can work when the rest of the electrical system is deactivated (i.e. when the car isn't running). So if you turn the control stalk to off, no power anyway. Turn it to LOW and the +12V pins of both connectors have power.
So, when fnpierce wrote:
What he's saying are the 'high beams' here are the inner lamps' What he's saying are the low beams are the outer (I assume). That's why that works: when you take the wire from inner connector, it's switched on by the low beams. So you wire it to the high and low beams, it'll have power when the lights are on. The ground wire from the low beams goes straight to chassis ground. Oh no what about the switch on the ground leg! Well, the switch on the control stalk ALSO turns the power supply in the inner lamp connector on and off, so this will work to switch the low beams. What about the high beams? Well, on these led lights, when you drive the high beam input, both things light up. You don't actually need to power both anyway. And connecting the ground wire from the inner lamps to the inner connector's ground means that when you engage high beams, you connect that left pin in the high beam connector to ground so the high beams will light up.
The limitation of this strategy is that your outer lamps are JUST low beams, and your inner lamps are JUST high beams. Why? For the outer lamps, you connected the ground to vehicle ground, and you're switching whatever power is connected with the high beam's supply, which is switched on when the lights are on at all. So either you connect the outer lamp's low and high pins to this power, or just one, either only the low beams work OR the high+low are both on. There's no pin available anywhere in the stock harness that gets power only when the high beams are on, this is how switching the grounds becomes a problem.
Similarly, the inner lamps you're getting around the 'no +12V pin when the high beams are on' problem by connecting the ground to the switched ground in the high beam connector. But this means you have the same choice: connect the high beam pin to the power and get the high+low beams when the high beams are on, or get just the low beams when the high beams are on, but there's no path to ground when the high beams are off, and if you use the vehicle ground, now there's no way to switch this light between high and low, it's switched by the low beams.
I might be totally wrong about this as I didn't test it, but my guess is, the way the fnpierce's lights are set up, you have an outer lamp that's always a low beam, and you have an inner lamp that's lights up when you turn on the high beams (but it lights up the high and low beams). So you're basically just sacrificing "all four low" mode, and not using the outer lamp's high beams. I'm not even sure if this is bad. It's a lot easier to do, and there's a lot less moving parts (you're getting rid of four relays) and a lot less trouble to install it.
If you want all four low, all four high, the solution is relays. Control the relays with the ground switching in the factory harness (because the relay doesn't care which side of the coil is which), and wire the power up in the correct direction through the switched side of the relay.
That's what the Holley H840 harness, which you can find for less than $20, is supposed to do.
Holley basically produces no documentation about this harness, other than the tantalizing clue 'Designed for vehicles with switched ground application (typically older Toyotas)'. I was hoping that since it specifically says 'for older Toyotas' that this would be fairly plug and play but for me at least it was not.
The harness doesn't come with anything that explains its pins or anything. The first problem is the harness has three pins, which means one of them must be common since there's two relays. Spoiler alert: it's the one with the black wire, presumably because it's supposed to be ground. Of course, we're using this backwards, so we actually need this wire to be the wire that always has +12V, and we're going to switch the grounds. So you'd think, ok, I bet the put the pin for the common connector in the side of the H4 connector that matches the "ALWAYS ON WHEN THE LIGHTS ARE ON" pin in the factory harness. No, they don't. So you need to make an adapter or chop up the harness.
Ok so concern #1 when you make your adapter / harness mods is "get the black common wire to the +12V pin (the right most pin in my diagram above).
The second concern I still don't totally understand, but the relays are not totally independent like I'd assumed they were. From my other thread:
The trouble here is that when the high beams are switched on, the low-beam pin in the outer connector does not get its connection to ground broken. It stays connected, and the high beam ground is connected as well. So both relays will be energized in high beam mode.
The trick here is both high and low lights are lit if the headlamp gets power to the high beam pin. So we just have to make sure to power the high beams with the red relay (the relay that has all the red wires going to it). I don't know how stable this color coding is from Holley so probably best to check on your own before you install it or make any adapters or start chopping it up.
It's very easy to make pin-swapping adapters using something like these Holley H820s.
The final wrinkle that I ran into really made me feel like I was nuts, but the pinout on my headlamps does not follow the info on Holley's site or on any site for any headlamp i've ever seen, which is what my first post was about. There's two differences:
* Ground pin is swapped to the other outside pin
* High beam pin is the middle pin
I still have no idea what to make of this and even writing it down makes me think it sounds wrong and I must be mistaken. But you can see the pics in the post.
So you have to adapt the output side of the Holley harness to make it so the red relay is driving the high beam pin of your LED headlamps, the white relay is driving your low beam pin, and ground is on the other side.
Finally, you gotta figure out how to drive two of these harnesses because you need the other lights to work. What I did was cut up two of those H820 things and mult the outside connector on the battery side, because I was thinking it would be convenient to have the other low beam connector to fix the dash lamp and would save me figuring out how to route the power. In reality, I needed to splice extra wire into one of the harnesses' power connectors anyway, and it wouldn't have been any more annoying to make it a few feet longer, and for reasons I don't understand the high beam indicator in the dash is lighting up anyway.
For mounting the relays, I put one down where Tor puts his, the other is bolted next to the battery. For ground wires I used the bolts in the bottom outside edges of the headlight frame.
Lastly, I couldn't find the four bolts that hold each light in its frame, so I used some stainless M4-0.7s I had around with loctite. I did order the replacement adjustment bolts from partsouq. Replacing this bit of hardware was good, the old little bolts were in really, really rough shape but Kroil + screw pliers did the job pretty easily. Other bits seemed to hold up pretty well.
I think that about covers it? I didn't cut into the factory harness so should be easy enough to switch back if this doesn't work so well.
Basically, slcfj62 has said everything you need to understand how the headlights on these trucks work in one thread or another, but I was confused about a few things when I started doing this:
* fnpierce's incredibly helpful thread about upgrading to some JW Speaker lights doesn't add any new relays, it just swaps some pins around.
* more recently, vankho posted this thread about using Holley RetroBright with the Holley H840 harness, which does have include new relays to deal with the switched grounds
So do you need to find a place to mount the new relays or not? The answer is it depends how you want your headlights to work.
On the factory setup, there's four headlamps. I'm going to call them the 'outside' lamps and the 'inside' pairs to avoid saying high beam since that will get confusing, but in the stock setup, the inner pair light up only on high beams. The outer sealed beams have three pins: ground, low beam, high beam. There are two filaments inside (or whatever lights up in there, gas envelopes, I don't know, it's easy to see though if you unook the inner lamps and switch between high and low on the outers). The inner units only have two pins, and only have the single filament that's lit in high beam mode. To summarize
* FACTORY OFF: Everything's off
* FACTORY LOW BEAM: Outer pair low beam lit, inner pair off
* FACTORY HIGH BEAM: Outer pair LOW + HIGH lit, inner pair HIGH lit.
When the FJ62 was initially designed in Japan, the engineers inserted a flaw in it, because perfect things are an offense against God. The engineers decided the flaw would be inserted in the design of the headlight electrics, which as a result, are completely deranged.
The outer pair of lights are driven by three pin H4-style connectors. These connectors, looking into the connector as if you were standing in front of the truck looking towards the grille (so the driver lights on your right side, passenger lights are on your left side) have the following pin arrangement:
LOW BEAM GROUND +12V THATS ON WHENEVER THE HEADLIGHTS ARE ON
HIGH BEAM GROUND
For the sealed beam lights, this is ok, they don't care about polarity. The ground pins are left floating when that particular light isn't supposed to be on.
The inner lamps connector, the ones that are only used for high beams, has only two pins:
HIGH BEAM GROUND +12V THATS ON WHENEVER THE HEADLIGHTS ARE ON
A lot of posts in here refer to the problem being that the system was designed with switched grounds. I get why people say that now but it was a bit confusing to me when I was trying to figure this out. The problem isn't really that the grounds are being switched. The LEDs will work fine if you switch the grounds. It's really that any replacement LED headlamp is going to only have one ground, and you can't wire it backwards, because the LEDs only work one way. So you can connect either of the switched grounds to the headlamp, but it's going to light whatever led in the headlamp has +12V on it when you do.
The clever dudes that fnpierce talked to noticed something important about the way the factory harness is set up though: Everyone says it has a 'hot common' and a 'switched ground, but in reality, the common is switched as well. When the lights are off, there's no power at the +12V pin in either of the connectors. This really confused me before I took it apart and tested it. I assumed "hot common" just meant there was a 12V supply wire that was energized whenever the car was on. No. I'm assuming this is so the lights can work when the rest of the electrical system is deactivated (i.e. when the car isn't running). So if you turn the control stalk to off, no power anyway. Turn it to LOW and the +12V pins of both connectors have power.
So, when fnpierce wrote:
What he's saying are the 'high beams' here are the inner lamps' What he's saying are the low beams are the outer (I assume). That's why that works: when you take the wire from inner connector, it's switched on by the low beams. So you wire it to the high and low beams, it'll have power when the lights are on. The ground wire from the low beams goes straight to chassis ground. Oh no what about the switch on the ground leg! Well, the switch on the control stalk ALSO turns the power supply in the inner lamp connector on and off, so this will work to switch the low beams. What about the high beams? Well, on these led lights, when you drive the high beam input, both things light up. You don't actually need to power both anyway. And connecting the ground wire from the inner lamps to the inner connector's ground means that when you engage high beams, you connect that left pin in the high beam connector to ground so the high beams will light up.
The limitation of this strategy is that your outer lamps are JUST low beams, and your inner lamps are JUST high beams. Why? For the outer lamps, you connected the ground to vehicle ground, and you're switching whatever power is connected with the high beam's supply, which is switched on when the lights are on at all. So either you connect the outer lamp's low and high pins to this power, or just one, either only the low beams work OR the high+low are both on. There's no pin available anywhere in the stock harness that gets power only when the high beams are on, this is how switching the grounds becomes a problem.
Similarly, the inner lamps you're getting around the 'no +12V pin when the high beams are on' problem by connecting the ground to the switched ground in the high beam connector. But this means you have the same choice: connect the high beam pin to the power and get the high+low beams when the high beams are on, or get just the low beams when the high beams are on, but there's no path to ground when the high beams are off, and if you use the vehicle ground, now there's no way to switch this light between high and low, it's switched by the low beams.
I might be totally wrong about this as I didn't test it, but my guess is, the way the fnpierce's lights are set up, you have an outer lamp that's always a low beam, and you have an inner lamp that's lights up when you turn on the high beams (but it lights up the high and low beams). So you're basically just sacrificing "all four low" mode, and not using the outer lamp's high beams. I'm not even sure if this is bad. It's a lot easier to do, and there's a lot less moving parts (you're getting rid of four relays) and a lot less trouble to install it.
If you want all four low, all four high, the solution is relays. Control the relays with the ground switching in the factory harness (because the relay doesn't care which side of the coil is which), and wire the power up in the correct direction through the switched side of the relay.
That's what the Holley H840 harness, which you can find for less than $20, is supposed to do.
Holley basically produces no documentation about this harness, other than the tantalizing clue 'Designed for vehicles with switched ground application (typically older Toyotas)'. I was hoping that since it specifically says 'for older Toyotas' that this would be fairly plug and play but for me at least it was not.
The harness doesn't come with anything that explains its pins or anything. The first problem is the harness has three pins, which means one of them must be common since there's two relays. Spoiler alert: it's the one with the black wire, presumably because it's supposed to be ground. Of course, we're using this backwards, so we actually need this wire to be the wire that always has +12V, and we're going to switch the grounds. So you'd think, ok, I bet the put the pin for the common connector in the side of the H4 connector that matches the "ALWAYS ON WHEN THE LIGHTS ARE ON" pin in the factory harness. No, they don't. So you need to make an adapter or chop up the harness.
Ok so concern #1 when you make your adapter / harness mods is "get the black common wire to the +12V pin (the right most pin in my diagram above).
The second concern I still don't totally understand, but the relays are not totally independent like I'd assumed they were. From my other thread:
The trouble here is that when the high beams are switched on, the low-beam pin in the outer connector does not get its connection to ground broken. It stays connected, and the high beam ground is connected as well. So both relays will be energized in high beam mode.
The trick here is both high and low lights are lit if the headlamp gets power to the high beam pin. So we just have to make sure to power the high beams with the red relay (the relay that has all the red wires going to it). I don't know how stable this color coding is from Holley so probably best to check on your own before you install it or make any adapters or start chopping it up.
It's very easy to make pin-swapping adapters using something like these Holley H820s.
The final wrinkle that I ran into really made me feel like I was nuts, but the pinout on my headlamps does not follow the info on Holley's site or on any site for any headlamp i've ever seen, which is what my first post was about. There's two differences:
* Ground pin is swapped to the other outside pin
* High beam pin is the middle pin
I still have no idea what to make of this and even writing it down makes me think it sounds wrong and I must be mistaken. But you can see the pics in the post.
So you have to adapt the output side of the Holley harness to make it so the red relay is driving the high beam pin of your LED headlamps, the white relay is driving your low beam pin, and ground is on the other side.
Finally, you gotta figure out how to drive two of these harnesses because you need the other lights to work. What I did was cut up two of those H820 things and mult the outside connector on the battery side, because I was thinking it would be convenient to have the other low beam connector to fix the dash lamp and would save me figuring out how to route the power. In reality, I needed to splice extra wire into one of the harnesses' power connectors anyway, and it wouldn't have been any more annoying to make it a few feet longer, and for reasons I don't understand the high beam indicator in the dash is lighting up anyway.
For mounting the relays, I put one down where Tor puts his, the other is bolted next to the battery. For ground wires I used the bolts in the bottom outside edges of the headlight frame.
Lastly, I couldn't find the four bolts that hold each light in its frame, so I used some stainless M4-0.7s I had around with loctite. I did order the replacement adjustment bolts from partsouq. Replacing this bit of hardware was good, the old little bolts were in really, really rough shape but Kroil + screw pliers did the job pretty easily. Other bits seemed to hold up pretty well.
I think that about covers it? I didn't cut into the factory harness so should be easy enough to switch back if this doesn't work so well.
