MASH835

Fog Lights Switch Mod (so you can switch on the fog lights anytime)
This mod is for ES300 models '97 to '01.


DISCLAIMER:
Try this modification at your own risk. I'm not responsible for any personal injury/death, mistakes/long term effects and/or damage to property.
The procedure posted here is based solely on my experience with my 2001 ES300. Wiring and connectors can vary widely between models and years so always verify your car before making any connections.


I used BananaGS mod as starting point it is very helpful. However, you will not need to disassemble anything except may be the coin box to reach to the fuse block and connect the wire (see below).
It is also very important that you check if it works for you (in step #3).

Step 1:
Locate the fog light relay. You can put your finger on it and feel clicking sound when you switch on the fog light while the headlights are also on.

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Step 2:
Now remove the fog light relay carefully. You will see two golden pins (relay switch pins) and two silver pins (relay coil pins). Make sure that your fog light relay looks like this.

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Just to make it clear, how the relay works (briefly):
(Please Note this is not the real wiring diagram, only a drawing to explain the idea)

When both headlights and fog lights are switched on, current will pass from pin (1) to pin (2) of the relay (relay coil pins) and the pin (3) and pin (4) of the relay (relay switch pins) will be connected so the fog lights are switched on.

The idea is to make current passes continuously from pin (1) to pin (2) from different source other than the headlights. So all we have to do is to use a different power source to pin (1) of the relay.

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Step 3: (Very important to check before you do this mod!!)
Now look at the fog light relay and its socket as in the image.

Please make sure the following conditions are true for you (you will need to use a voltmeter or a 12V test light). Keep the engine running and fog lights relay removed and switch on the headlights.

1) Connect the positive lead of the voltmeter to #(4) of the relay socket and negative lead to the ground. The voltmeter should give you positive voltage reading (from power source -fog fuse- to fog lights through the relay switch).
2) Connect the positive lead of the voltmeter to #(1) of the relay socket and negative lead to the ground (make sure headlights are on). The voltmeter should give you positive voltage reading (from headlights -headlight fuse- to the relay coil to fog lights switch).

Now switch off all the lights , and the engine.

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Step 4:
Now make an extension wire like that one made by BananaGS (you can use male/female spade connectors on each side of the wire), and connect male pins of the relay to the socket as the in image.

Connect all pins of the relay to their original position in the relay socket, except for #(1) of the socket leave it unconnected.

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Step 5:
Connect pin #(1) of the fog lights relay to a 12V power source using 14-18 gauge wire (such as from a wiper fuse as BananaGS did, or tail light fuse).
For me, while trying to make sure the idea works, I connect it to positive wire coming from the cig. power outlet first while the engine is on.

I like to use one of these (I got mine from www.accessafuse.com)

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Finally, Make sure you make good connections and good luck for you.

Enjoy

juan01

very nice write up!

I wonder if this is the same for the 92-96 models?

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Thank you juan.

I am not sure but I think the idea is the same for all models. You have to find the fog lights relay and check which pin is receiving the current from the headlights as shown in the steps in the mod and then get different power source to it, but as I said I am not sure!

lexusk8

This may be the first successful fog light mod write-up I've seen during my time in the ES forum (and a great one this is!) Nice to see you used your '01 ES as an example

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Thank you lexusk8.

btw, i checked the '00 ES300, the wiring is the same for the fog lights relay as '01.

If anyone try this mod for the US ES300, please tell me if it works the same.

Good luck!

justin97

worked perfect for my 97 es, expect i ran the power wire to the tail light fuse. so, i can turn on my fogs with my park lights, instead of anytime.

redzeppelin

Will they still automatically turn off when you turn the engine off?

ES BL155

iTrader: (3)

it depends on where u get your power source from. if you get it from the cigarette lighter it should turn off once you take out the key.

Braddism

The mod seems to work except the switch is bypassed completely. Is that correct? I'll just run it to the taillights. Anyone know where the tail light fuse is? I don't see one under the hood. Inside maybe?