Can I run the fog lights without the headlamps? (1 Viewer)

[NautiqueGuy]

simple question.

I’d love to replace the fog bulbs with an amber colored LED, but that only makes sense IF I can run them without the headlamps. You know, as a true fog lamp...

Is there any way to do this? Or should I just grab white LEDs to match the HID ?

This is a 2014 btw...

 

[ToyotaMatt]

No , or at least not stock like u have it / how toyota designed it

U need to do whats called " Any time Fog Light / Lamp Modification "


this will allow u to run them in lights off , park position and high beams

 

[gaijin]

No , or at least not stock like u have it / how toyota designed it

U need to do whats called " Any time Fog Light / Lamp Modification "


this will allow u to run them in lights off , park position and high beams

OK. Great! And just how would one do that on a 2013 Land Cruiser?

TIA

P.S. A Google search turned up no LC-specific info and nothing I could access without a membership/registration - which I don't like to do.

 

[NautiqueGuy]

Agree with the above.

The search feature here turns up no results...

 

[linuxgod]

It's technically illegal to run fog lights without headlights in most (all?) states. Having lived up the top of a steep mountain road, I know it's much more effective to run fog lights without headlights reflecting back at you, but most of the state DOT rules say something like "fog lamps meeting the requirements may be used with lower headlamp beams".

It's also illegal in most states for lights which aren't DOT approved to be uncovered when on road, even if they're not in use, but many of us have light bars uncovered and are not bothered.

You might look at rewiring the fog light relay into the parking light circuit rather than the headlamp circuit, so that you can run them with your parking lights. After all you may want to run fog lights without headlights in very thick fog, but you still need side markers and tail lights on so others can see you.

 

[HRTROB]

Wait, the headlights have to be switched on to be able to use the fog lights? In my GEN spec 200, the fog lights can be turned on even with just the parking lights switched on. I have the front fog light wiring diagram from a GEN/Europe spec 200 if anybody needs it

 

[619TOY]

Agree with the above.

The search feature here turns up no results...

 

[OregonLC]

The control side of the fog light relay gets ground from ECU and 12V+ from the tail relay. That the tail light (parking light) is on but the fogs don't come on means that the ECU logic is inhibiting ground on that circuit without the head lights being on. So you would need to wire directly from the fog light switch to the relay, bypassing the ECU. Could be done fairly simply just would take time.

Shown below, you would need to cut the Red wire 4 from the combination switch and reconnect the switch side to pin 1 of the Fog relay, also severing the Red wire from the main body ECU. This would give fog control using the factory switch with the tail lights. You would need to power the fog relay from a different switched (or unswitched) source if you wanted truly independent operation.

This is all in theory, try at your own risk. But the logic seems reasonable. I'm always a bit worried with a Canbus vehicle of what unintended consequences there may be with messing with factory controls.

 

[linuxgod]

Wait, the headlights have to be switched on to be able to use the fog lights? In my GEN spec 200, the fog lights can be turned on even with just the parking lights switched on. I have the front fog light wiring diagram from a GEN/Europe spec 200 if anybody needs it

Maybe the non-US vehicles are different but yes, I leave my fog lights in the "on" position and they will not light up unless the headlights are on (DRLs and parking lights don't count). They also turn off when you flip on the high beams.

The above may very well be due to US (NHTSA) operating requirements and may be different in other countries.

 

[linuxgod]

Shown below, you would need to cut the Red wire 4 from the combination switch and reconnect the switch side to pin 1 of the Fog relay, also severing the Red wire from the main body ECU. This would give fog control using the factory switch with the tail lights. You would need to power the fog relay from a different switched (or unswitched) source if you wanted truly independent operation.

Or just buy some aftermarket Rigid lights and mount them inside the bumper or grill and wire to a separate switch. AOB has tons of 200-series switches you can use.

 

[OregonLC]

That would work too. I have the OPOR ones (Rigid clones) mounted flush in the MetalTech bumper shell. Those come with adapters that plug right into the factory harness, so it's a nice PNP running off of the existing system.

 

[HRTROB]

The control side of the fog light relay gets ground from ECU and 12V+ from the tail relay. That the tail light (parking light) is on but the fogs don't come on means that the ECU logic is inhibiting ground on that circuit without the head lights being on. So you would need to wire directly from the fog light switch to the relay, bypassing the ECU. Could be done fairly simply just would take time.

Shown below, you would need to cut the Red wire 4 from the combination switch and reconnect the switch side to pin 1 of the Fog relay, also severing the Red wire from the main body ECU. This would give fog control using the factory switch with the tail lights. You would need to power the fog relay from a different switched (or unswitched) source if you wanted truly independent operation.

This is all in theory, try at your own risk. But the logic seems reasonable. I'm always a bit worried with a Canbus vehicle of what unintended consequences there may be with messing with factory controls.

View attachment 1722472

View attachment 1722474

I wouldn't cut the red wire on pin 4 of the combination switch. I'd cut the red wire on pin 4 of connector E1 on the main body ECU, then tap that red wire that goes to pin 34 of EA2 to pin 4 of the combination switch. That way, the fog light relay is grounded directly by the combination switch, and the switch also continues to send the signal to the main body ECU which will turn on the fog light indicator on the dash but only when the low beams are switched on

 

[OregonLC]

That probably would work if you really wanted to see the indicator light with the low beams. I say probably because of concern that when the tail light relay is energized it could result in stray 12V+ current on pin 28 of ECU harness A. Not sure how sensitive the ECU is. That leg appears to only want ground and it would be exposed to an energized 12V circuit (if you tapped into pin 1 of the fog relay with the tail lights on it would glow). I'd probably want to throw a diode on it just to make sure. Seems like it's a risk without much benefit (indicator would only be on with low beams, not tail lights or high beams). Then again, this might just me being really conservative. I'd probably run it completely off the ECU just to be safe.

 

[HRTROB]

That probably would work if you really wanted to see the indicator light with the low beams. I say probably because of concern that when the tail light relay is energized it could result in stray 12V+ current on pin 28 of ECU harness A. Not sure how sensitive the ECU is. That leg appears to only want ground and it would be exposed to an energized 12V circuit (if you tapped into pin 1 of the fog relay with the tail lights on it would glow). I'd probably want to throw a diode on it just to make sure. Seems like it's a risk without much benefit (indicator would only be on with low beams, not tail lights or high beams). Then again, this might just me being really conservative. I'd probably run it completely off the ECU just to be safe.

Pin 1 on the relay is the negative side of the coil. It won't feed +12v from from any of the other pins on that relay.

 

[OregonLC]

Electricity will follow the path of least resistance. My concern is that the ECU could become the ground path for that circuit. If I'm understanding your suggestion you'd be landing Pin 1 of the fog light relay onto the switched leg (Wire 4/28) of the fog light portion of the combo switch. When that switch is open (and the tail light relay is closed), it creates a potential ground path for the fog light relay through the ECU. Even when that switch is closed, the ECU could become a ground path if it's resistance was less than the switched leg. (Sorry for the crappy whiteboard drawing).

I'm not saying the ECU has the ability to become the ground path or that anything damaging would occur if it did. However, there is the potential for damage. Risking an ECU on something as trivial as a fog indicator lamp that only glows when in low beam isn't worth that risk to me but I understand what you're trying to achieve with your idea.

This discussion has actually motivated me to see if I can make it happen. Primarily for having the fog circuit on with the high beams.

 

[HRTROB]

Electricity will follow the path of least resistance. My concern is that the ECU could become the ground path for that circuit. If I'm understanding your suggestion you'd be landing Pin 1 of the fog light relay onto the switched leg (Wire 4/28) of the fog light portion of the combo switch. When that switch is open (and the tail light relay is closed), it creates a potential ground path for the fog light relay through the ECU. Even when that switch is closed, the ECU could become a ground path if it's resistance was less than the switched leg. (Sorry for the crappy whiteboard drawing).

I'm not saying the ECU has the ability to become the ground path or that anything damaging would occur if it did. However, there is the potential for damage. Risking an ECU on something as trivial as a fog indicator lamp that only glows when in low beam isn't worth that risk to me but I understand what you're trying to achieve with your idea.

This discussion has actually motivated me to see if I can make it happen. Primarily for having the fog circuit on with the high beams.

View attachment 1722655

I see your point. I guess if you really want to run the fog lights with the parking lights and keep the dash indicator without risking any damage to the body ECU, you can use a standard SPST relay to ground the ecu and the fog light relay. Cut the red wire on pin 4 of the combination switch, feed it to pin 85 of a standard SPST relay, then +12v to pin 86. Pin 30 to ground, then 87 to the main body ECU and fog light relay.

 

[619TOY]

Electricity will follow the path of least resistance. My concern is that the ECU could become the ground path for that circuit. If I'm understanding your suggestion you'd be landing Pin 1 of the fog light relay onto the switched leg (Wire 4/28) of the fog light portion of the combo switch. When that switch is open (and the tail light relay is closed), it creates a potential ground path for the fog light relay through the ECU. Even when that switch is closed, the ECU could become a ground path if it's resistance was less than the switched leg. (Sorry for the crappy whiteboard drawing).

I'm not saying the ECU has the ability to become the ground path or that anything damaging would occur if it did. However, there is the potential for damage. Risking an ECU on something as trivial as a fog indicator lamp that only glows when in low beam isn't worth that risk to me but I understand what you're trying to achieve with your idea.

This discussion has actually motivated me to see if I can make it happen. Primarily for having the fog circuit on with the high beams.

View attachment 1722655

Two additional points to consider with adding an external relay:
1. Positive 12V will be resting on the input to the BCM on the fog light switch wire when the relay isn't activated and that wire may only ever "see" open or ground normally, it may never "see" 12V in the factory configuration.

2. You'll be introducing an AC spike directly into the BCM every time the relay latches and unlatches.

Both of these byproducts can be alleviated with diodes, but I just figured I'd throw it out there. And maybe neither would even have a negative effect in the first place...

 

[linuxgod]

As a techie I know it's fun to figure out how to make this work, but for the OP my suggestion would be:

1. Buy these - https://www.amazon.com/Rigid-Industries-50481-SAE-Light/dp/B00Q1RS83M
2. And buy one of these for your dash - Toyota OEM Replacement Push Switch in green for Highlander Tacoma Tundra 4 Runner and FJ Cruiser -Air On Board
3. Mount the lights in the lower part of the bumper. You can control them independently of any other lighting. Problem solved.

Now if you guys want to start talking about how to make the LED parking lights on the 2013+ operate as DRLs I'm game...

 

[NautiqueGuy]

I too would love to know how to get those LEDs to function as DRLs.

 

[gaijin]

I too would love to know how to get those LEDs to function as DRLs.

I have the DRL's (High Beam bulbs at a reduced voltage on my 2013LC) turned off via the info system.

If I want DRL's, I just turn on my Parking Lights. Sure, not only do I get the LED strips below the headlight housings to turn on, I also get the parking lights and rear running lights as well - no big deal, it's all about visibility, right?

HTH