Another headlight issue - main beams stay on.

[Eurasiaoverland]

I decided to upgrade the headlights on my 60 with Koito semi-sealed beam (H4//H1) headlights. Mine is a 1989 so has four headlights, like a US FJ62. I made a simple harness which is driven by the old headlight connectors on the LH side (passenger side) of the wiring harness. I have three relay-driven circuits: Outer dipped beam, outer main beam and inner main beam. Each relay's trigger circuit is driven by the original wire in the harness, and the trigger circuit is earthed back to the earths in the original headlight connectors.

The relays switch from the battery, through to new headlight connectors (which are connected to the new headlights) and back to battery.

The issue I have is as follows:
When I turn headlights on (dipped beam), they come on normally.
If I flash the high beams (stalk towards myself), they stay on when the stalk returns to the dipped beam position. They only go off when I turn the headlights off at the stalk (switch back to side lights/parking lights).
If I turn the headlight on and push the stalk forward to main beam, the main beams come on, with the dipped beams, and won't switch off when I return the stalk to dipped beam.

If I run an LED in the main beam switch, it flickers on for a split second when the main beams come on. If I run the original incandescent bulb, nothing.

The above symptoms happen whether I have an LED, incandescent, or no bulb at all in the high beam indicator.

I'm not great at electrics, but I suspect that the issue is due to me not understanding how the original headlights are switched. There is a single relay switching the headlights on/off and somehow from dipped to main, even though there is only one, single circuit headlight relay in the vehicle. I suspect that the main beam circuit is somehow earthing from both ends and staying on even when there should not be current to the main beam wires. Would it help if I earthed the trigger circuits for my relays to the body, and not to the headlight circuit?

Thanks for reading this far, I'm hoping someone better at electrics than I can suggest what has gone wrong!
EO

 

[Lead Head]

Do you have a schematic drawing of how you wired your relays? Without that, it will really be impossible to troubleshoot.

 

[TreadingLight]

You need to make sure both the ground and the positive is switched, identical to the factory circuit.

If it were me, I'd look for the old forum thread where @slcfj62 posted the wiring diagrams for his Ultimate Harness. He no longer makes and sells them but he gifted the schematic to the community.

 

[Spike Strip]

Post in thread 'Headlight wire harness FJ60 and FJ62'

Aug 16, 2025

I'll even throw in one for the FJ80. I could only find the schematic and not the wiring diagram. I only built two of these and I don't remember whether this is the accurate schematic for those, but for what it may be worth to someone, here you go:

Now that I'm looking at this again, I believe this harness was built for a guy that wanted his low beams to stay on when he went to high beams.

• slcfj62

Post in thread 'Headlight wire harness FJ60 and FJ62'

Aug 16, 2025

Here are the diagrams for the FJ60. It's been a long time since I looked at these, so hopefully they match version level:

• slcfj62

• 

 

[Eurasiaoverland]

Thank you for all the responses, and to the link to the wiring diagram - I'll have to sit down and look at it carefully.

Here is a schematic of how I made my wiring loom. Mine is a four headlight model so I have outer main beams, outer dipped beams and inner main beams in separate, relay-driven circuits.

I'll try to explain the circuit here:

-I use the factory feed for the LH headlights (inner and outer) to drive the relay solenoids. Note that mine is a RHD so this is the passenger side.
-I have main outer, dipped outer and main inner relays. The trigger circuit (solenoids) are earthed back to the W-B earth wire in the respective original headlight connector - they are not grounded directly like slcfj62's circuit diagram implies.
-The relays switch fused battery voltage to the bulbs. Each relay drives the left and right light.
-The bulbs are earthed to the body, or effectively straight to the battery as it is the same point where the main battery negative wire earths on the LH wing (fender).
-The RH factory headlight connectors are not used at all, they remain unplugged.

Unfortunately, I don't have a wiring diagram for a four headlight 60, only the 1981 wiring diagram for a two headlight model, but I think the circuit is much the same (there is still only one factory headlight relay). I do not have the Euro style circuit with separate high and low beam fuses.

@Lead Head thanks for the comment on switching both positive and negative, but I'm afraid I'm not smart enough to understand how that works in practice! Could you explain please? I have the relay solenoids running back to the original wiring, so I would assume they are switched the same as the original wiring. But my bulbs are only switched at the relay (positive only).

Would it be an issue that my RH original headlight connectors are not connected? From what I have seen of the Koito headlight and loom kit, these also only use a single factory headlight connector, but I'm not sure if the instructions stipulate that it must be the driver's side connector.

Thank you very much for your time looking at this! I have a freshly rebuilt nut-and-bolt restored BJ60 with an engine upgrade and I'm very annoyed with myself for screwing up this headlight 'upgrade' (though the headlights do work, so I can still drive it. But it won't pass a serious technical inspection.

EDIT: I think I have one fuse for the Inner headlight circuit, and one for the outer headlight circuit, rather than main and dipped beam circuits as I have draw it. But that does not make any difference to the logic of the circuit.

 

[Eurasiaoverland]

With reference to the below, I have sat down with a friend and worked out at least one problem with my wiring loom. I have effectively been using the R-Y as a ground, as it is common to both main and dipped beam filaments. For the mains, it is on the negative side of the filament, but not for the dipped beams. So I need to change the way that the dipped beam relay is integrated into my wiring loom.

 

[TreadingLight]

You should have 4 relays also if you look at @slcfj62's design. Follow it exactly if you want your high beam indicators to work.

 

[Eurasiaoverland]

You should have 4 relays also if you look at @slcfj62's design. Follow it exactly if you want your high beam indicators to work.

That was going to be a further question; why that fourth relay is there. I have a sealed relay box in my engine compartment from a Toyota Avensis which carries up to four single pole relays, so it would be problematic for me to accommodate a fourth relay which is of a double pole form. I'm going to fix my mistake as outlined above and see how things work. If it is still not switching correctly I'll have to start from scratch with slcfj62's design. Thanks.

 

[Eurasiaoverland]

I'm an idiot. At some point I must have had the idea to switch the factory terminal positions around in the headlight connector to the H4 configuration (which is different from the sealed beam configuration). But when I came to rebuild by wiring loom, I used the original sealed beam positions. I just swapped the terminals around in my wiring loom and it works perfectly, with (LED) high beam indicator.

So,
-my circuit above is useable (note the obvious mistake on the main beam outer relay terminals, and the fuses are for inner/outer lights respectively, not main/dipped beam as I have drawn).
-you don't need a fourth relay in the system (using an LED bulb at least) to have a working high beam indicator.

My loom is basically a neatend, shortened version of the Koito outer and inner halogen bulb wiring kits (the outer ones are sold by Toyota very cheaply, the inner looms are not supplied by Toyota as far as I know). All components are weatherproof (unlike the Koito relays) and there is no change to factory wiring. The wiring runs over the radiator shroud, using factory clamps and Japanese conduit which is exactly what would carry the battery cable if I had a 24 V model.

Here is my setup installed:

 

[TreadingLight]

Personally I'm not a fan of LED dash indicators but I know folks have gotten their HBI working with an LED after adding a headlight harness. I'm guessing the low current draw is the trick.

If it ever starts to flicker, yoink it outta there before it melts. I've seen posts of failed melted dash LEDs that looked a little dangerous.

 

[Eurasiaoverland]

Thanks. I tried the original incandescent and it's very dim (though as main beams are only used at night, this might not be an issue). I've seen other solutions of adding a resistor to the circuit but they seem to have a high failure rate. What causes the LED to melt?

 

[TreadingLight]

I think they are not all as resilient as we'd like. Quality.

The OEM circuit let's the HBI get power through the low beam filament when the high beams are on.

 

[Eurasiaoverland]

I think they are not all as resilient as we'd like. Quality.

The OEM circuit let's the HBI get power through the low beam filament when the high beams are on.

There's so little curernt flowing in the circuit now that it's just switching relays instead of sealed beam filaments, that I can't see it benig much of a risk. I may down-rate the HEAD fuses now to 7.5 A given that the relay solenoids are connected with 1 mm2 wire (16.5 A).

 

[AussieHJ6X]

Looks very neat and is inspiring me to finally get around to doing this on my ‘88 HJ.

Nice to hear you can get the HBI working with just the 3 relays. I’m not a wiring wizard, so cutting a relay/resistors from some of the circuits I’ve seen seems very much worth the effort of changing the dash globe to LED

 

[TreadingLight]

If you use 4 relays and follow @slcfj62 design, you can keep your normal incandescent HBI.

If you use 3 relays like @Eurasiaoverland, you'll need to use an LED HBI.

 

[AussieHJ6X]

My dash lights are very dim, so I’ve been meaning to swap them to LEDs anyway

(Probably should also check the A-pillar grounds and the dimmer function)

 

[TreadingLight]

The little green plastic bulb covers get cooked over time and dim the dash lights. If you buy normal bulbs get new covers for them. If you get LEDs (yuck) you can buy them colored.

Now that I'm thinking about it, I wonder if you can get incandescent bulbs with tinted glass instead of plastic covers...

 

[Eurasiaoverland]

I would think twice about LEDs, I like the soft glow of the original illumination. LEDs are invariably brighter (not what I want when driving at night), and don't spread light the same way that incandescents do - fine if the LED is behind an indicator card (e.g. the glow or fuel fiter warning indicatiors, )but not great for the illumination LEDs which rely on reflected light. I only went with an LED HBI because of the inherent issue of having very low current in the headlight circuit now.

But I absolutely recommend the headlight wiring upgrade. Even with standard Koito bulbs the difference is huge, and your headlight switch will thank you for it. I think I caught mine just before it burned out from the poor current switching design it came with from factory.

 

[AussieHJ6X]

Any tips on what to check to improve the brightness of the stock bulbs?

 

[Eurasiaoverland]

As the light is reflected from the bulbs inside the instruments, onto the light coloured surrounds or housings and then onto their faces, it's important that they are spotlessly clean. If your bulbs are old and blackened inside, or the green rubber caps hardened and opaque, that will also lose you light.