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Fog lights won't come on

Posted: Fri Jul 13, 2018 12:51 pm
by Plcd22
Hello, it has been awhile since I have been here = busy with work and life.

Anyway I tried searching the site some and couldn't find a good answer, so here is my question:

I have a 2003 Vibe with 190K miles on it. Have had it for 2 years now and the fog lights have never worked on it...?

Heres what I have tried:
1. Pulled bulbs (9006) and looked at to see if they were burnt out - appeared to be OK
2. checked the fuse box = fuses are OK
3. ordered a set off ebay (LED compatible for the 9006)
4. plugged in the new bulbs and nothing...?

Is there some other place I need to look, like for a relay or something?

Thanks in advance for your help!

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 1:27 pm
by Caretaker
did you try starting the car first and then turning on the fog lights? I somehow remember that either the regular lights had to be in the power on position (not DRL position) and/or the car had to be actually started.

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 1:36 pm
by Plcd22
Caretaker wrote:did you try starting the car first and then turning on the fog lights? I somehow remember that either the regular lights had to be in the power on position (not DRL position) and/or the car had to be actually started.
oh YES sorry forgot to mention that in the list.

5. started the vibe, put it in gear, tried low beams only and also high beams with the fog light switch in the on position = nothing

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 2:54 pm
by SlammedNiss
I assume you checked with a multimeter at the fog light and aren't getting power at all? There is a relay between the switch and the fog lights themselves. Not sure exactly where it is, but it's either under the dash or under the hood.

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 7:24 pm
by Plcd22
SlammedNiss wrote:I assume you checked with a multimeter at the fog light and aren't getting power at all? There is a relay between the switch and the fog lights themselves. Not sure exactly where it is, but it's either under the dash or under the hood.
thanks - I'll have to follow wires and see if I can track down a relay between there somewhere...

you mean besides in the fuse box right?

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 7:39 pm
by joatmon
The fog light relay is in the underhood fuse block. You can see it in the diagram on page 6-74 of the 03 owner's manual, (a PDF of which can be downloaded from viewtopic.php?t=755 ) its the one right next to the FOG fuse

Power for the fog lights comes from the battery, goes through the 100A ALT fuse, then through the FOG fuse, then the fog relay to the fog lights. The relay is switched by a combination of the fog light switch and the daytime running light module.

If there was a problem with the battery or the 100A ALT fuse, you would be worrying about a lot more than just the fogs.

The fog lights only come on when the headlights are in full low beam mode. They will not light when in half bright DRL mode, and will not light when headlights are high beam. The fogs do come on if you manually turn the headlights to full low beam, and turn on the fog light switch. Don't need the car to be running, don't need a key to check that.

One thing to check to determine which half of the circuit is problematic is to pull the relay and use a wire, or a paper clip to jumper the connections in the relay socket. When you pull the relay, there will be two probably silver colored tabs , those are for the relay coil, and two likely copper colored tabs. When the switches and DRL module put 12V across the silver colored tabs, the relay will close and connect then two copper colored tabs. If you jumper where those two copper colored tabs go, you can turn the fog lights on and completely bypass any control from the switch and DRL module. Let me know if that doesn't make sense, and I'll get around to finding a picture, but not tonight ;)

If you jumper that and the fogs come on, then the problem is probably in either the switch or the DRL module. If it doesn't come on, then the problem is in the bulbs, the FOG fuse, or something with the light socket or wiring itself.

The fog relay is similar to others in there, you can swap two and see if the prblem follows the relay or stays with the fogs

Re: Fog lights won't come on

Posted: Fri Jul 13, 2018 8:17 pm
by Plcd22
joatmon wrote:The fog light relay is in the underhood fuse block. You can see it in the diagram on page 6-74 of the 03 owner's manual, (a PDF of which can be downloaded from viewtopic.php?t=755 ) its the one right next to the FOG fuse

Power for the fog lights comes from the battery, goes through the 100A ALT fuse, then through the FOG fuse, then the fog relay to the fog lights. The relay is switched by a combination of the fog light switch and the daytime running light module.

If there was a problem with the battery or the 100A ALT fuse, you would be worrying about a lot more than just the fogs.

The fog lights only come on when the headlights are in full low beam mode. They will not light when in half bright DRL mode, and will not light when headlights are high beam. The fogs do come on if you manually turn the headlights to full low beam, and turn on the fog light switch. Don't need the car to be running, don't need a key to check that.

One thing to check to determine which half of the circuit is problematic is to pull the relay and use a wire, or a paper clip to jumper the connections in the relay socket. When you pull the relay, there will be two probably silver colored tabs , those are for the relay coil, and two likely copper colored tabs. When the switches and DRL module put 12V across the silver colored tabs, the relay will close and connect then two copper colored tabs. If you jumper where those two copper colored tabs go, you can turn the fog lights on and completely bypass any control from the switch and DRL module. Let me know if that doesn't make sense, and I'll get around to finding a picture, but not tonight ;)

If you jumper that and the fogs come on, then the problem is probably in either the switch or the DRL module. If it doesn't come on, then the problem is in the bulbs, the FOG fuse, or something with the light socket or wiring itself.

The fog relay is similar to others in there, you can swap two and see if the prblem follows the relay or stays with the fogs
Thanks for ALL the great info - I'll check that out! 8-)

Re: Fog lights won't come on

Posted: Mon Jul 16, 2018 3:48 am
by zbyers
Joatman hit it head on. Swap the fog relay with a neighboring one. If no lights, then you have an issue elsewhere.

On my 03, I did the "fog mod" so the fogs are on at all times. One of my wires going to the switch slipped off of that. Unknown if you've done said mod, but I'd pull the cover off the bottom of the steering column. There should be a green/orange wire (if I remember correctly) under there which is for the fogs. Make sure it isn't spliced and diced if a previous owner or something did the fog mod.

Fog mod can be viewed here: viewtopic.php?f=28&t=9844&p=105604