fog lights don't turn on, high beams wonky

Really odd problem here. Let me preface this by saying that I'm halfway through doing a dash and instrument cluster LED lighting overhaul. I don't know if the high beams/fog lights *ever* worked the way they were supposed to since I got the car, as I never really went through a thorough test until now, and the headlights were replaced by previous owner with LED units. So I don't actually know for certain what's been mucked with.

Anyway here's what it's doing:

with the headlights on, key to 'on' position (motor not running, I have it half disassembled right now...) when I press the fog light button, the high beams turn on, but the fog lamps do not, and the hi beam indicator on the cluster does not. When I flick the high beam switch, the high beams also come on, the fog lamps and hi beam indicator do not.

What's wrong here, and how do I:

A) make the fog lamps come on when I hit the button

B) make the high beam indicator on the cluster light up?

Before you ask, I am 100% positive the high beam indicator LED works, and is installed with the correct polarity for the circuit. I tested by swapping it with the turn signal lamp, and both lamps share an anode on the circuit, so if they're installed the same way and one works, so should the other.

EvilStig":1ajves1u said:

What's wrong here, and how do I:

A) make the fog lamps come on when I hit the button

Click to expand...

I'm almost positive that because of the aftermarket LED headlights (not positive so correct me if I'm wrong), this circuit will not operate as it should. What I did with mine was bypass power to the relay by tapping into a switched 12v. More specifically, the timed-delayed circuit that is also tripped by an open door once the key is removed. Here's a write-up I printed off from here some time ago:


To be more clear in case the notes I made on the pictures (found online years ago) are confusing. .
-Remove (don't cut) the red/white wire and shrink wrap the end, secure our of the way.
-Insert a scrap piece of wire where the red/white once was but you'll have to crimp your own terminal to it which will connect to the relay.
-The other end of that new jumper wire will attach to the white/green wire with a splice of your choice.

The newly tapped wire (white/green) is a timed delay circuit. It'll stay on with the key off for ~thirty seconds or until the door is opened. . . Just like the headlight circuit on the 6th gen. Hope this helps

EvilStig":1ajves1u said:

B) make the high beam indicator on the cluster light up?

Click to expand...

EvilStig":1ajves1u said:

. . the headlights were replaced by previous owner with LED units.

Click to expand...

Because the LED lights don't have the same resistance as the OE incandescents, our cars don't know how to act with LEDs. . Some install resistors but I find that too dangerous as those will get very hot, plus you'll need the proper size. What I did was simply add a 194 bulb/socket to each side (on the low beam circuit), this added enough to fool the circuit into thinking there were regular halogens in place and these bulbs don't get that hot.

To test all this in case you don't believe me simply reinstall OE lights and everything should function properly.

FC Zach":3aefmhjg said:

Because the LED lights don't have the same resistance as the OE incandescents, our cars don't know how to act with LEDs. . Some install resistors but I find that too dangerous as those will get very hot, plus you'll need the proper size. What I did was simply add a 194 bulb/socket to each side (on the low beam circuit), this added enough to fool the circuit into thinking there were regular halogens in place and these bulbs don't get that hot.

To test all this in case you don't believe me simply reinstall OE lights and everything should function properly.

Click to expand...

a 194 bulb is 3.8 watts supposedly, so at 12v you could accomplish the same with a 37 ohm resistor, a good chassis mounted one should stay cool enough... although I don't know how much your replacements draw to work that into the calculation.

FC Zach":3aefmhjg said:

I'm almost positive that because of the aftermarket LED headlights (not positive so correct me if I'm wrong), this circuit will not operate as it should. What I did with mine was bypass power to the relay by tapping into a switched 12v. More specifically, the timed-delayed circuit that is also tripped by an open door once the key is removed. Here's a write-up I printed off from here some time ago:
To be more clear in case the notes I made on the pictures (found online years ago) are confusing. .
-Remove (don't cut) the red/white wire and shrink wrap the end, secure our of the way.
-Insert a scrap piece of wire where the red/white once was but you'll have to crimp your own terminal to it which will connect to the relay.
-The other end of that new jumper wire will attach to the white/green wire with a splice of your choice.

The newly tapped wire (white/green) is a timed delay circuit. It'll stay on with the key off for ~thirty seconds or until the door is opened. . . Just like the headlight circuit on the 6th gen. Hope this helps

Click to expand...

How does the celica detect the headlights are on? If we added the resistor like in part B, would we even need to do this? I don't really care if I can turn the fogs on without the headlights, just that I can turn them on at all.

Also, I still don't really see how this ties into the high beams turning on when I hit the fog lamp button? If there's a wiring fault of some kind causing this, I'd be hesitant to modify any of the relays and potentially fry something.

EvilStig":v53i2mo1 said:

How does the celica detect the headlights are on?

Click to expand...

I haven't looked into this anymore, especially after finding a way around the issue.

EvilStig":v53i2mo1 said:

If we added the resistor like in part B, would we even need to do this? I don't really care if I can turn the fogs on without the headlights, just that I can turn them on at all.

Click to expand...

No, I did this because I preferred separate control of the fogs with or without headlights.

EvilStig":v53i2mo1 said:

Also, I still don't really see how this ties into the high beams turning on when I hit the fog lamp button? If there's a wiring fault of some kind causing this, I'd be hesitant to modify any of the relays and potentially fry something.

Click to expand...

My guess is because they can't be on at the same time, per OE design. . I'm sure they're tied together so the fog relay is off when highs are on. As for the modification, it's completely reversible (as long as you don't the red wire in half).

I should have started by saying that I had all the same symptoms as you have mentioned so the above recommendations are what I found to work from experience, your mileage may vary

Also, if you don't want to fool with resistors/bulbs and you want a simpler way to confirm any of this, try reinstalling OE lights. If things are still not working then you know you have a wiring issue.

I had to do some searching. . Here's an old thread where on page 4 I copy/pasted a reply from Truck-Lite tech support.

http://www.alltrac.net/phpBB2/viewtopic.php?f=24&t=43942&p=457014#p457014

Thanks, unfortunately I don't have the OE lights.

Could you tell me what model headlights you're using? If I can figure out what their current draw is it will give me an idea of how much more is needed from my setup.

oh cool, I think those are the same ones as are in my car. That simplifies things. If a 194 bulb on the low beam circuit on each side solved the problem for you, I should do just fine using a couple of 30ohm resistors mounted up out of the way on the chassis. Thanks!

No problem

FC Zach":1x7qtrpo said:

I'm almost positive that because of the aftermarket LED headlights (not positive so correct me if I'm wrong), this circuit will not operate as it should. What I did with mine was bypass power to the relay by tapping into a switched 12v. More specifically, the timed-delayed circuit that is also tripped by an open door once the key is removed. Here's a write-up I printed off from here some time ago:
To be more clear in case the notes I made on the pictures (found online years ago) are confusing. .
-Remove (don't cut) the red/white wire and shrink wrap the end, secure our of the way.
-Insert a scrap piece of wire where the red/white once was but you'll have to crimp your own terminal to it which will connect to the relay.
-The other end of that new jumper wire will attach to the white/green wire with a splice of your choice.

The newly tapped wire (white/green) is a timed delay circuit. It'll stay on with the key off for ~thirty seconds or until the door is opened. . . Just like the headlight circuit on the 6th gen. Hope this helps

Click to expand...

Is yours a JDM? I noticed the harness is reversed on mine... but more importantly, the wires aren't the same.

From this picture it looks like this is definitely meant to be the same harness.

However from the back you can see that there is no red and white wire. There's a blue and yellow, and a white and black (I assume ground). I'm guessing the blue and yellow is the switch power I want to replace, but I see several white and green wires all of much larger gauge. Is there a way to be sure it's one of these that I want to splice into?

At this moment my cluster is still oput and I'm working on removing the headlights so I can wire in the resistors and replace the bumper.

Are you in the driver's or pass. side kick-panel?

The fog light relay/wiring is in the passenger side kick-panel.

FC Zach":ti67j1tf said:

The fog light relay/wiring is in the passenger side kick-panel.

Click to expand...

oh well that would make a difference... guess I'll have to pull that one out tomorrow. Odd place for it...

I had something similar happen to mine. The last post on this thread fixed it for me. And it also lets me run the fog lights on low and high beam.

http://www.celicatech.com/forums/archiv ... 64b91b22b3

okay so, is it the large red and white wire? or the small red and white wire? There's 2, one goes to the relay trigger and the other to the switch.

The relay trigger wire.

FC Zach":1xebzam4 said:

The relay trigger wire.

Click to expand...

ok thats what I figured, although I hooked it up like that and it doesn't work :doh:

not sure what to try next.

Speaking of, I can't for the life of me seem to figure out how the headlight wiring works. The three contacts appear instead of being ground, low, and high like you would expect,t o be some weird varying combination of voltages that are different for each side. I'm not even sure where to hook up the resistors. Does someone have a pinout or wiring diagram I can refer to?

EvilStig":13qmy46u said:

although I hooked it up like that and it doesn't work :doh:

Click to expand...

Using the write-up?

EvilStig":8muyp57t said:

Speaking of, I can't for the life of me seem to figure out how the headlight wiring works. The three contacts appear instead of being ground, low, and high like you would expect,t o be some weird varying combination of voltages that are different for each side. I'm not even sure where to hook up the resistors. Does someone have a pinout or wiring diagram I can refer to?

Click to expand...

This what you're looking for? Add resistor/bulb to low.