Hello everyone,

I have a newish (to me) 2001 SR5 that I've been working on for the last several months. I'm trying to get my fog lights working but am at a road block and need some advice. My rig has the Hella Micro DE lights that were originally corroded to hell and replaced with new replacement units and bulbs. From what I can tell, I'm not sure that my rig originally came with fogs as I don't have a switch on the turn stalk like others have reported, rather I have a switch in the dash.

So, I know that the lights are only supposed to come on when the low beams are on and they turn off otherwise. My question to you all is, I cannot for the life of me get them to turn on. Can anyone offer any advice on what to do next? Here's what I've done:

1) Checked fuse under hood, fuse is fine. Also swapped with a different, known-good fuse and still no luck.

2) Checked the relay and I believe it also works (passes click test). The relay config looks as follows:

--
-- | |
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If I apply 12v to uppermost and lowermost horizontal pins, the relay clicks.

3) I used a DMM to check the current using advice from this thread and found the following:

a) When car is OFF (no keys in), I have constant 12v between the two vertical pins on the right. This doesn't change, except for jumping up to 14v when car is running. Lights on/off it doesn't matter, always 12v here. At any time, I can put a jumper wire between these two and the fog lights will turn on. Even with car off, keys out of the ignition.

b) I ONLY have 12v between uppermost and bottom most horizontal pins with low beams ON and fog light switch ON. When I turn fog light switch off or turn on high beams, 12v goes to zero (as intended, I believe).

I've verified continuity with my DMM between one of the rightmost vertical pins (can't remember whether it was the left or right one atm) and both connectors that plug into the fog lights under the bumper. I also have continuity from the battery ground and the ground on both connectors at each of the fog lights. And again, when I jump the vertical pins, the lights turn on with and without the vehicle running, so I know that continuity and my connections are good.

4) I've also tried switching the relay with the one used for the Defrost and still no luck getting them to turn on.

I'm at a loss and not really sure how to proceed. I know the switch works as I can see measurable voltage changes in the horizontal pins when the switch is flipped. I suspect that the relay is working because it does pass the click test and subbing in a different relay doesn't change anything. And, I know I have continuity in my wiring and that my lights work as I can bypass the circuit and manually power them with 12v.

Anyone have any suggestions on how I should proceed?

I can offer the 2001 for light EWD. :-)

Attached Images

Front_Fog_Light_2001.pdf (39.6 KB, 50 views)

Thanks brillo, I'll trace the wires and make sure it follows the EWD here this weekend. Haven't had much time this week with the in-laws in town.

Griff,
That's how my 2001 4Runner came when I purchased it new - Hella Micro DE fog lamps and an illuminated rocker switch to the left of the steering wheel.


Andreas

Oh! That's good to know. I couldn't find any info on whether they came stock with a dash switch instead of one on the turn stalk. So, maybe mine weren't added aftermarket

Okay so here's a small update. Long story short, still no luck.

However, I can confirm that I have switched voltage between the coil pins. 0V when low beams off and fog light switch off. Low beams on and switch I get anywhere from 9-11 volts (seems low?)

And as mentioned in my original post, I have constant 12v across two horizontal pins and when bridged, fog lights come on.

So, I turned my attention to the relay. When I apply 12v to top and bottom horizontal pins, I get an audible click and continuity between the switched (vertical) pins. Take 12v away and the continuity goes away, as expected. So, the relay seems functional. But, when it's plugged into the slot, it does not click when low beams are on and fog light switch is on.

So, it seems like although I have measurable voltage change between the coil in response to the fog light switch, the coil is not activating the switched side of the relay. I also cleaned the contacts of any dust/debris so I'm hoping that it's actually making contact.

Maybe I can try opening the top of the plastic relay housing and see if I can access leads on the coil side of the relay to see if it's making contact

A question for more electrically savvy folks out there, could a lower voltage on the coil side (when compared to the voltage on the switched circuit) impact whether or not the coil can activate the switch? Or maybe current on the coil side? Just spit ballin' here.

And thank you all for the help so far, it's truly appreciated.

Another update for anyone following...

I was able to verify the wiring as illustrated in the EWD that brillo provided. I then rigged up an experiment to measure the voltage on the coil side of the relay with without anything on the switched side.

So, with low beams on and fog light switch on, voltage between G/W and B/R was 12 volts when not connected to the relay coil. As soon as you engage the coil side of the relay, voltage drops to less than 1V and relay does not click.

I then repeated the exact same test with a 9V battery. Voltage between G/W and B/R wires was 9V when not connected to the relay coil. When the relay coil is connected, voltage stayed at 9V and relay audibly clicked.

So, this suggests there's a short somewhere in the factory fog light circuit (I think). As the dash fog light switch isn't a lighted switch, I'm assuming this was a kit added by the PO. So, I followed the wires from the switch up to under the steering wheel cover and see that they're tapped into a G/B and R/B wire.

Anyone out there have any thoughts? I'm curious if that switch is wired correctly. If not, I'm not sure how to proceed looking for this short as all fuses appear fine... I hope I'm not overlooking something simple...

Attached Images

         

It isn't a short... It sounds like high resistance in the coil trigger wire, if I'm reading your results correctly. You need a "strong" 12V at the coil positive (that doesn't droop when the coil is drawing power). Maybe those vampire taps are not not working so well (corrosion), causing all your issues.

I'd remove those and solder the connections to start, like this:



-Charlie