Fog light modification... Ideas?

[svxcess]

I will keep this simple. I would like to have the ability to have the fog light turn on independently of my normal headlights. I seems my 2 options are:

1. Run 12V through a relay and a separate switch to the fog lights and control it manually so I could have the fog lights work when the lights are totally off or just the parking lights are on.

2. Find out how to rewire or jump connectors so that my fog light switch could activate the lights when the light switch on the column stalk was in the parking lights position (as well as the normal headlight position) This is my preferred option.


Reasoning:

I do not know how the new HID system will operate in snowy weather from a standpoint of reflected glare from the snow back into my eyes or those of oncoming traffic. Since I drive quite a bit slower during these times, my need to see very far down the road with the headlights is decreased.

If I put H-3 HIDs into the fog lights (yes, they do exist) I may be able to use them as auxiliary headlights to still shine on the road adequately and not bother other drivers. I would turn these on with only the parking lights, leaving the main headlights off. They should be bright enough to adequately see, while also being bright enough to be seen by oncoming traffic.

Any thoughts from the electrical experts on how I would accomplish this modification and what wires to use? It seems like locating the parking light wire that connects to the headlight wire on the stalk and adding a splice to the parking light wire as well.

Something like a modified DRL system, but manually-controlled by the fog light switch and not automatically controlled by the ignition.


Am I making any sense here?

[ridered777]

Have a wiring diagram? My fog's don't work, and I've never taken the time to investigate, given my new HIDS... But this certainly sounds like a good idea.

I see your desire to run them to the parking lights - keeps them from being left on if all else fails, and your battery survives the catastrophe. On my previous car, I had fog's that would only work with the headlights activated, but altered them to work ALL the time. I just ran an 12v "jumper" wire to the power wire on it, and I was fine. I would assume that it would not be much more difficult on these cars, even if it was to run it to the parking light switch. You would just need a diagram, and my guess would be, that that circuit has and independent ground, all you have to do is splice the existing ground into that and you're good to go.

Trevor, correct me please.

[crazyhorse]

OK Here's what I've come up with. Taking power from the park light sw through the foglight sw to turn on a relay that turns on the bulbs. You STILL need a GOOD diagram to find the proper wires on the various switches. Then some simple wiretaps would suffice to run low current 12v to a relay.
Wiring it like my VERY CRUDE diagram would allow you to run them independently of the headlights.
First you'd need to unwire the foglight sw from the system, then run new wires, one from the tap in the parklight sw, the other to the relay. Then from the tap to the relay

I'm SURE Trevor will chime in to help, and correct me if need be.

[Trevor]

MY JDM car has the fog lights arranged such that they operate via a separate switch, which when turned on with the ignition on, brings on the fog lights together with the tail lights, but without the headlights. \

This would appear to be the only logical arrangement as one certainly does not want the headlights reflecting on fog, while the fog lights are set low to shine under the fog. Surely this is the object of having fog lights.

I would not wire the fogs such that they do not go off with the ignition. I have only days ago disconnected my parking lights as they tended to become accidentally left on, with a flat battery the result.

Sorry, but I must advise that your diagram is out of line. I could sort this out for you, but unfortunately I do not have a wiring diagram covering your car.

Head and fog lights are switched in the negative/ground circuit and include a relay for high beam. The circuitry is quite involved and incorporates blocking diodes in the indication light circuits. But do not let this deter you as separating the fogs should not be too difficult.

The approach will be to lift off the negative control circuit from the fogs and arrange things so that the existing switch provides a ground without the headlights being switched on. However I can not advise in detail without knowing how the existing system is arranged.

[crazyhorse]

Originally Posted by Trevor

Sorry, but I must advise that your diagram is out of line. I could sort this out for you, but unfortunately I do not have a wiring diagram covering your car.

That's why I'm here, to learn

[Crazy_pilot]

My fog lights act as daytime running lights. That is, they are on during the day when the headlights are off. When I turn the headlights on the fogs turn off and are controlled by the dash switch.

[Trevor]

Originally Posted by svxcess

I will keep this simple. I would like to have the ability to have the fog light turn on independently of my normal headlights. :

Firstly, I thank you sincerely for posting to me, at considerable expense, a copy of the US Electrical Manual. With this on hand I have been able to sort out what is rather a convoluted method of achieving a rather simple outcome. The brand of logic, the automotive electrical profession uses is incredible.

The existing fog light switching is interlocked in two ways via the fog lamp relay. Firstly in the negative/ground leg, via the dimmer switch, such that this must be in the dim/low position. Secondly by using a B+ supply to the fog lights, via the left hand head light relay, such that this must be energised, i.e. the head lights switched on.

The fog light relay is energised via terminal MB3 and 15 amp fuse, 24 when the fog light switch is closed, but only provided the headlamp relay is activated. This is the circuit which must be altered so that supply is not dependent on the head light circuit.

All things considered, the deciding factor will be accessibility. My problem is that I do not have a US left hand drive car to tinker with, so that I will have leave the physical aspects still to be sorted out.

A red coded conductor runs from terminal (1) on fog relay connector F2, to main fuse board terminal MB3. The question is as to whether this is a separate lead which can be removed at MB3, or is there a junction made within the loom? The wiring diagram is not exact in this regard, but considering the location of the components involved, I would expect there to be a separate lead.

If so, this lead should be coloured red and as only relay current is involved, the conductor should have a relatively small cross section. When disconnected the fog lamps when illuminated should extinguish, and this should provide a means of identification. The object will be to disconnect the lead and connect it constant point of supply e.g. terminal MB6, (i.e. Switch the lead from MB3 to MB6).

An alternative would be to make alterations at the fog lamp relay, situated under the dash panel. Here the same red lead connects to pin (1) and should be disconnected. Pin (1) must then be provided with an alternative supply from a nearby source.

If a permanent supply is used as per the most convenient connection points as above, there is a problem to consider. It is best that the fog lights are dependent on the ignition being on, otherwise they could be inadvertently left on, resulting in a flat battery. I have experienced this as a result of leaving side parking lights on.

Therefore it would be wise to pick up a supply from a point switched via the ignition, either accessory position, or ‘on’ position. Fuse board terminals FB10, 15 amp fuse 2, and FB17 20, amp fuse 3 are shown as empty and either could provide the required supply point.

A second and possibly an easier alternative, if a constant supply to the relay is used, would be to change the existing constant B+ supply to the fog lights to an ignition accessory switched source. This could be done by moving the red/yellow lead on connection FB41, 15 amp fuse 4, to FB10 or FB17.

I have tried to keep my explanation as concise and simple as possible, but without detail the requirements would be difficult to exactly understand. Explanations of this sort are not easy to transfer as text. Any attempt to rehash the drawings from the manual would be futile. Proper schematics are the answer. Not bastardized, half cock wiring diagrams.

[JIMSVX]

I have also tried to chase down the USDM fog light circuits so that I could use them as DRL's. After reading Trevor's discussion of a possible solution I though i could do it. However I gave up trying to find the locations of the various relays and wiring. So I scrapped that plan and just started over with a circuit that is independent of the existing wiring. The result is that the fog lights can be switched on with the existing fog light switch when the ignition is in the "on" position, regardless of the headlight operation.

The new circuit adds a relay that is powered by the existing fog light switch. The 2 fog lights draw a total of 8 Amps so I used a standard 30 Amp auto relay to handle the current (Radio Shack 275-226 - $6.79). The relay is mounted above the transmission resistor, behind the battery, in a plastic box with the shift-kit vacuum switch.

The schematic below shows the mod with the new wiring in red.




I started by removing the battery so I wouldn't short anything out and to provide access to mount the new relay.

I then popped out the fog-light/cruise/security switch assembly and removed 2 of the existing wires on the fog light switch (white and yellow wires circled in the photo.) The third wire (red) provides power for the indicator light in the switch and is not removed.




In the new DRL circuit the center contact of the fog light switch provides switched power to the fog light relay. This requires running a wire from this contact (circled in the photo) to the relay behind the battery. You can see the 2 insulated wires that are disconnected from the switch.




I tapped into the ignition switch +12V power ("on" when the ignition switch is on) by connecting a short jumper wire (circled in this photo) from the cruise control switch +12V power to the fog light switch L/H terminal. Be sure you don't remove the existing wire from the center terminal of the cruise control switch when the jumper is added. This could require 3 hands!




This completes the wiring modification of the switch. I won't discuss getting the wire through the firewall and out to the relay. I never enjoy working under the dash.

The next step involves making the connection to the negative side of the existing circuit at the fog lights. I broke into the wiring at the fog light disconnect behind the driver's side headlight assembly. This photo shows the location of the disconnect to the left of the headlight bubble level. Above the circle you can see the wire I spliced into this existing wiring. This wire connects to the Red-Grn wire inside the ribbed sleeving and is routed over to the new relay, behind the battery. In the existing fog light circuit this wire goes from the fog lights to the existing fog light relay. Since this existing relay can not be switched (we disconnected the wires from the switch) there is no need to break this wire. Be sure to connect to the Red-Grn wire, NOT the Red-Yel wire which is also inside the sleeving. The Red-Yel wire is connected to +12 V for the fog lights and it is always hot.




The final connections to the relay are shown in the schematic diagram.

This picture shows the complete assembly before everything is buttoned up. I located the relay in a 5"x2.5"x2" plastic box (Radio Shack 270-1803) along with my transmission shift-kit vacuum switch. This photo shows the box and the wiring with the battery removed. To the right of the box is the cover with an attached metal tab that is used to mount the box under the upper Transmission resistor mounting bolt.




Here's the box mounted above the Transmission resistor.




Finally, the installation with the battery back in place.

[svxcess]

Jim,

Thanks for such a detailed write-up. A couple of the photos are still a little confusing as to wire colors, especially in the photo with everything in the relay box. many wires that I can't seem to trace

I am assuming the green wire from the switch assembly goes through the firewall and goes to pin 85 of the relay. After that, it gets confusing because of the similar color wires going to the shift kit.
I also assume red wires are for +12V at pin 87 and black wires at pins 30 and 86 for chassis ground. can you enlighten me a little further?


Trevor,

With your vast expertise, do you see any potential problems here? What about high beam operation?

I assume that since the original fog light relay is disconnected, the fog lights would not automatically shut off when I switch to high beams. If my headlights are on normally , along with the fog lights and I switch to high beams, the fog lights will still be on. That's a lot of light!!

My original idea was to

With the fog light switch in the OFF position, allow for normal headlight lo-beam/high beam/ fog light operation as originally designed (with fog lights shutting off when high beams were used; two different lighting needs) but allow me the option of

With the fog light switch in the ON position, having fog lights when the parking lights were on, using the column stalk. I could drive in bad weather with just the HID fog lights (column switch in parking light position).

Turning the column switch to the headlight position would allow me headlight and fog lights, or headlights alone, and normal high beam operation (Shutting off the fog lights when switched on)
.

[svxual]

hmm very weird !! my fog lights turn off and on with my dash switch wether or not any other lights are on ??

[LetItSnow]

Trevor, I'm gonna CN your 100% correct text real quick here. Our current circuits:

+12 - HEADLIGHT FUSE - HEADLIGHT RELAY - FOG RELAY TOGGLE - FOG SWITCH - HI/LO BEAM SWITCH - GROUND

+12 - FOG BULB - FOG RELAY - GROUND

You're basically looking at an "AND" - the fog switch and the hi/lo beam switch both close the circuit together. Kid stuff.

So, how to throw an "OR" into the works?

...PARKING LIGHTS - FOG RELAY TOGGLE - FOG SWITCH - HI/LO BEAM SWITCH - GROUND

+12 - FOG BULB - FOG RELAY - GROUND

Not much to change there! Is there any reason that changing the (low current!) source shouldn't work?

[svxcess]

Originally Posted by svxual

hmm very weird !! my fog lights turn off and on with my dash switch whether or not any other lights are on ??

On the USDM cars, That is how it should be. using the lo-beam headlights, you should be able to turn fog lights on and off using the fog light switch.

Even with the fog light switch ON, the fog lights will not come on if either the column switch is in the 1st position (parking lights only) or the high beams are used.
.