91 hdj81 headlight issues. (1 Viewer)

[IxEquilibrium]

Hello everyone I am a long time creeper but first time posting. I have recently picked up a nice 91 RHD diesel 80 and I was warned of some issues. I have been searching here and can't find anything like this particular problem. So here goes

My signals /running lights and tail lights all work just fine but both my headlights high and low do not. They can be made to work by pulling the fuse for the dome lights. Yes you heard me correctly. Removing the fuse for the dome lights will turn my headlights on whether the key is in the ignition or not. I checked the headlight wiring up until it enters the loom but I was hoping somebody might had come across something like this before and might know the problem. Thanks a bunch guys and gals.

 

[gnarlynick2072]

Hello everyone I am a long time creeper but first time posting. I have recently picked up a nice 91 RHD diesel 80 and I was warned of some issues. I have been searching here and can't find anything like this particular problem. So here goes

My signals /running lights and tail lights all work just fine but both my headlights high and low do not. They can be made to work by pulling the fuse for the dome lights. Yes you heard me correctly. Removing the fuse for the dome lights will turn my headlights on whether the key is in the ignition or not. I checked the headlight wiring up until it enters the loom but I was hoping somebody might had come across something like this before and might know the problem. Thanks a bunch guys and gals.

That is certainly weird. Looking at the wiring diagram, the Dome Fuse should be independent of the headlight fuses. Perhaps there is a short somewhere where the headlight circuit jumps to the Dome circuit. Do your interior lights work with the Dome fuse in?

Do you have a copy of the electrical diagrams? That will help you a lot. Also, there seems to be a bunch of s***ty custom wiring jobs in these JDM trucks so anything that doesn't look Toyota could be an easy first step.

 

[IxEquilibrium]

Yes I had noticed some aftermarket wiring in there for sure. (Led tail lights and module, double din with a bunch of weird Japanese features. And it has halo hid head lights. Day time running lights wired in to the horn haha lots of good stuff)

The dome lights and stereo function just fine with the fuse in place. When the fuse is pulled the head lights come on and the radio and dome lights die. Very odd.

I do not have a wiring diagram sadly.
Thanks for your time.

 

[gnarlynick2072]

If you type in "offroad80s fsm" on google you can find the link to the fsm downloads. The wiring diagrams are at the end of the chassis manual (the 88 MB document).

It's always a mess trying to figure out what the previous owners were doing in japan... I had headlight issues as well but I think your issue is probably due to the entire headlight system shorting with the some circuit. Perhaps check in the junction box.

 

[tacosupreme]

Toyota has a weird system for the headlights. The wires going to the bulb are +12V all the time, both of them. When you turn "on" the headlight switch, it grounds out one leg of the bulb circuit turning the lights on. I've been trying to wire in my aux driving lights to come on with the high beams and found out about the strange set up. I wonder if the dome lights share a common ground with the headlights? Either way, you will have to chase wires if you don't have a schematic.

 

[IxEquilibrium]

Sounds good. I will download the fsm and start going through that tonight. I appreciate the input and I'm happy to be part of the cruiser community

 

[gnarlynick2072]

Toyota has a weird system for the headlights. The wires going to the bulb are +12V all the time, both of them. When you turn "on" the headlight switch, it grounds out one leg of the bulb circuit turning the lights on. I've been trying to wire in my aux driving lights to come on with the high beams and found out about the strange set up. I wonder if the dome lights share a common ground with the headlights? Either way, you will have to chase wires if you don't have a schematic.

This. That was my problem with my headlights, bad ground connection. Would be more likely than the +12V circuit maybe. Lol

 

[IxEquilibrium]

So you had the same problem with your headlights as I am having?

 

[IxEquilibrium]

Sorry I misread never mind. Haha

 

[Squash]

Tracked that for a long time and finally wired a ground via dash mounted switch to engine bay light relay.
I had noticed that just a plain test light poking around in the relay would switch on the headlight and this was my cure.

Yes there was some crazy JDM wiring!
Had the steering wheel of numerous times, replaced the OEM stalk with another stalk, you may need to accept this and move on, I feel for you.

 

[3ontwo]

Did you ever find the issue
Bought a 94 cruiser that had a toggle to the headlight relay and removed it and plugged the relay in now headlights always on.
I replaced the headlight switch removed the alarm and still headlight are always on (only headlights) unless I remove relay.

 

[jonheld]

Did you ever find the issue
Bought a 94 cruiser that had a toggle to the headlight relay and removed it and plugged the relay in now headlights always on.
I replaced the headlight switch removed the alarm and still headlight are always on (only headlights) unless I remove relay.

Download the 94 EWD from the resources section.
Some of the answers in this particular thread do not apply to US spec. Only the high beam bulbs are switched ground on a US spec 80. The low beams are switched +12.

If your low beams are on all the time regardless of stalk switch position, then someone bypassed the stalk switch due to failure. You should be able to troubleshoot this pretty easily.

 

[jonheld]

And please pick 1 thread and stick with it. If you post to multiple threads, it gets a bit confusing for folks to follow.

 

[3ontwo]

And please pick 1 thread and stick with it. If you post to multiple threads, it gets a bit confusing for folks to follow.

I get it. I was not getting far on my thread and figured I found someone who already fixed the issue.
Thanks for the help!

 

[Dusten]

Did you ever find the issue
Bought a 94 cruiser that had a toggle to the headlight relay and removed it and plugged the relay in now headlights always on.
I replaced the headlight switch removed the alarm and still headlight are always on (only headlights) unless I remove relay.

If you can pull the relay and the lights turn off you need to check two easy things.

Verify when the relay is out that you have an open across one point of the relay. When power is applied the relay should close contacts and pass power through. This is how relays work.
IE pins 1 and 2 are the coil.
Pins 3 and 4 are the signal.
So when you turn on the headlights 1 sends power through the relay and energizes the coil which moves the contactor and applies power from 3 to 4.

If the relay is showing continuity all the time, the relay has failed.

If the relay checks good, verify the power to the relay coil. It should come and go whyyou turn the head light switch on and off.

 

[jonheld]

IE pins 1 and 2 are the coil.
Pins 3 and 4 are the signal.

Pins 3 and 4 are the coil (logic)
Pins 1 and 2 are the closure (load)

 

[Dusten]

Pins 3 and 4 are the coil (logic)
Pins 1 and 2 are the closure (load)

I was using an example as I don't have the schematic in front of me. That's why I said IE.

Most vehicle relays are 85/86 for 12v and ground and 30/87 12v fused/lights

The air craft I work on use x1 and X2 for the relay coil.

So your blanket statement isn't needed.

 

[jonheld]

I was using an example as I don't have the schematic in front of me. That's why I said IE.

Most vehicle relays are 85/86 for 12v and ground and 30/87 12v fused/lights

The air craft I work on use x1 and X2 for the relay coil.

So your blanket statement isn't needed.

That was not a "blanket" statement. It was specific to the circuit in question.