pianoman41

Okay, for anyone that wants to run their fog lights with just their parking lights on, I've figured out how to do it. I did it on my '02 TL-S and it works fine. I know some posted here before wanting to know *why* someone would want to do that (I believe in some states like CA it's illegal to run just fogs), but here in MA you can run just fogs and parking lights at dusk, in the rain, etc. Or if the fog is so thick that just fogs gives you better visibility you can run the fog/parking combo without low beams (even at night). This post may seem lengthy but I tried to be as explicit as possible. Maybe this can get added to the FAQ.

First my warning: Although is mod is 100% effective and safe to do, I absolve myself of all claims of damage to your vehicle should you not be able to complete this mod correctly (or you pound a couple 40s before trying it).

Time to complete: 20-30 minutes, even for a beginner
Tools needed: Short phillips-head screwdriver, small pair of scissors (or razor knife), some type of in-line electrical connector, crimping pliers for electrical connector

Background: Because laws vary from state to state, Acura must make sure that its lighting is 50-state compliant. So even though some states allow it, they must wire the car so the fog lights (a) cannot be operated independant of the lights, (b) cannot be operated with just the parking lights, and (c) cannot be operated when the high beams are on. This mod changes the fogs so they will now do (b) in addition to how they normally function.

What the mod does: When the fog light switch is pressed, the current wiring system has the first fog light relay (there are two--this one is in the passenger side footwell) check the position of the light stalk. If it is switched off or to parking lights, no power passes to the second relay which powers the fog lights. Once it is switched to low beams, power passes through the first relay which then in turn powers the underhood relay and sends the high voltage (20A) to the fogs and lights them. The mod rewires and fools the fog light switch into thinking the low beams are on when the light switch is moved to the parking light position.

Procedure:
1. Remove cover from driver's side fuse panel. This cover is the entire end-piece of the dash. You need to open the driver's door fully to properly access this panel. It is held in place only by pressure clips. Simply pull up and out at the very bottom to start the loosening process. Gently apply pressure to the side closest to the driver and the top and the whole cover will pop out. Notice there is a long ridge on the side closest to the firewall. Make sure that side goes in first when putting the cover back on.

2. Loosen left side of driver's underdash kick panel. Although you could remove this whole piece, you only have to loosen the left side near the fog light switch to do this mod. Looking in though the opening you just made with the cover removal, you should see two brass-looking phillips-head screws. One is close to the front of the dash, one is down behind some wires holding a long thin brace in place, closer to the firewall. This is the screw you need to remove. It is the *only* screw that holds the driver's side underdash kick panel in place. Once you've removed the screw, you can loosen the left portion of the underdash kick panel by gently pulling on the piece. There are two clips at the top front, close to the bottom of the gauge cluster. You pop these clips out and the left side will come away from the dash. *This is as far as you need to remove the underdash kick panel.*

3. Unplug wiring harness to dash light dimmer switch. This is a simple plug harness that is indexed so it only goes back one way--no need to remember how it went in. This gets the cables more free for the next step.

4. Remove the fog light switch from the dash. Easiest way is to reach in from the side and grab it gently from behind (sounds like some of my dates). Squeeze gently top and bottom and push forward (towards where driver sits). The switch should pop out and be hanging by its wiring harness. Unplug the wiring harness. Press the tab in on one side of the harness and pull gently out. Set the switch aside and push the wiring harness back through the opening and bring it out through the side so you can work on it easier.

5. Spice the wires. The wiring harness consists of an inline, 5-prong plug, which is connected by five 18-20 gauge wires that are individually exposed for about an inch and then are bunched together by some rubber conduit tubing. Take the scissors or razor knife and carefully cut open the tube to expose more of the wires. You need to cut back about two inches, because you're going to want about three inches of slack to work with. Once you've cut the tubing, fan all the wires flat. You have five wires going to the harness. They are:

1. White/Blue - Ground side of indicator light (green light that shows fogs are on)
2. Blue/Red - Power to passenger side footwell relay
3. White/Red - Power from headlight switch
4. Red/Black - Power from taillight relay
5. Red - Connection to dash light brightness controller

Wire number 4 provides power to the icon on the switch whenever the lights are on (parking lights/taillights are all on one circuit). Wire number 3 provides power through the fog switch *only* if it detects the headlight switch in the low-beam position. So what we do is splice wires 3 and 4 together, thereby bypassing the headlight switch altogether. Now, whenever the taillights have power, so will this leg of the switch and the fogs will come on when the switch is pressed.

You can use whatever means you wish to join wires 3 and 4 together. Just remember you *don't* want to cut them, just splice the two together. I highly recommend an inline automotive wiring splicer (the kind that looks like a double-barrel shotgun from the end). These types of splicers are meant to be slid on over an exisiting attached wire and a second wire's free end is slid into the other side of the connector. The connector is then crimped and the latch cover is closed. However, because both of these wires are connected at both ends, if you use this type of connector you will need to drill out or punch out the solid end of the connector so both sides are completely open on each end. Then simply slide the wires into the connector, crimp the metal blade down through the wires and snap the plastic retaining tab closed. If you're good with solder you can solder in a jumper between wires 3 and 4, but that makes the mod much more permanent. I strongly recommend a two-wire inline connector and crimp.

6. Reassemble the fog light switch. Take the wiring harness from the side and push it back through the hole in the dash where the switch goes. The wiring harness for the dash light dimmer control is sort of tied with this one so you have to make sure you keep them separate and only push the fog light harness through the hole. Snap the wiring harness onto the fog light switch (it can only go one way). Then gently push the fog light switch back into the dash opening (make sure it is right-side up--green light on top, icon on bottom).

7. Replug the wiring harness into the dash light dimmer switch. Self explanatory.

8. Reattach underdash kick panel by pushing gently in area of the clips until they snap into place (remember there are two at the top, just under the gauge cluster)

9. Replace the phillips screw in the brace for the dash panel.

10. Replace driver's side fuse panel cover. Remember to start it by inserting the side closest to the firewall first. It just snaps into place.

That's it--you're done. The only thing you've changed is now the fogs will come on whenever you have the light switch either in the parking light position or in the low beam position. NOTE: The fogs will *still* go off when you use high-beams so this mod will not cause trouble for those who live in a place where it is illegal to drive with high beams and fogs together. Making them come on *with* the high beams is a much more in-depth mod and will not be dealt with here. What's more, if your fogs are on and you shut off just the headlight switch, the fogs go off too (like the factory set-up). Remember it this way--whenever the taillights are on, the fogs can also be on (*except* for when high-beams are also on).

Whew! I know it seems like it is complicated, but this is a very easy mod. If you've crimped wires before in a car it's even easier. Most of you could do this in 20 minutes, no more than 30 minutes for a real beginner.

If you have any further questions, please email me and I will try and help you out.

mr tl

sounds good
too bad it doesnt help me though

sounds like there are zero drawbacks.

nice

rockinTLS

Pianoman,

That was a real good writeup. Even had the appropriate disclaimers. I printed it out and will take a look at in depth while staring at my car to determine whether or not I want to mess with the factory wiring.

The one thing you might want to consider with the connectors you used is that humidity can now access the wires. I'm sure it is not too much better in MA than North Carolina where I live. Eventually, it might cause a problem. Just my $.02.

ACTUP

Great right up....but does anyone know how to do this for the first gen TL's????

RAdams

Agreed... excellent instructions! A moderator would do well to copy this to the FAQs.

pianoman41

Actually, the mod doesn't expose any more wire than the factory set up. There is no bare wire exposed anywhere. The conduit tube that you cut back to access the wires is there just to group them together for easy routing. They are all individually insulated like every other wire in the car. Splicing the two together with the splice like I used just crimps a metal blade down over the top of each wire and the housing of the connector insulates that part. So no exposed wire--no humidity problem. I suppose there is the question of the exposed metal blade *inside* the connector, but this is no different than another inch down the wire where it meets the harness plug for the fog light switch. The factory connections to the harness plug are all exposed, in fact more so than my connection.

bioyuki

Can someone check to see if this is legal in California?

SoundSpeed

Thanks for the instructions pianoman41.
I am going to see about putting this in the FAQ.

CarFreak

Good stuff! If I get this to work, then I will have to change my sig!

Road Rage

I am not a foglight freak, but this was a truly fine post!

As an EE, I can tell you that the exposed wire, even if there was one from this mod, is no big deal. There is plenty of exposed wire inside a car. Only the Weather Pak connectors are truly weatherproof, and they are used under the hood and places where moisture can wreak havoc with low voltage, computer connections.

rockinTLS

I stand corrected. Again, excellent post!

Road Rage

I did the mod this evening - took me about 30 minutes. I guess I am slow, plus I have big old ham mitts and had a bit of trouble reaching in to release the fog light switch.

Pianoman is right on the money with the instructions, and I commend him for his detail.

A couple of adds to the great post:

1) The quick splices are available at track auto near the fuse section. They are dark blue - get the 16-18 gauge ones.
2) You will need a long nose pliers or adj pliars to "tap" the connector into the quick splice.
3) I found it easier to remove the switch next to the fogs first (the VSA/cruise switch) to get at the foglight switch.\

It reall does look tough - I got up behind a 540i automatic with the fogs and parkinging lights only (it was dusk) and he got all nervous as if the big bad TL was gonna bite his ass. Given the chance, I might have!

I also de-badged the rear and the 3.2 and S badges now dress-up my engine compartment.

mvs

do the fogs now stay on with the high beams?

pianoman41

No they do not. The only change this mod does is allow the fog lights to come on with just the parking lights. There is a separate leg to the fog light switch that checks to see if the high-beams have been activated. The blue/white wire #1 is the ground side and it is a switched ground. When the headlight switch is set to high-beams, it cuts the circuit to the blue/white wire in the relay, thus breaking the ground and shutting off the fog lights. If you wanted to get fancy, you could probably jumper the blue/white wire to a common non-switched ground and then the fogs would stay on when the high-beams are on. That would be a much more time-consuming mod, however, I have *not* studied this further and DO NOT recommend this mod at this time (there may be more implications in wiring that circuit to a non-switched ground).

Road Rage

Why would you want to run hi beams and fogs.

Here is some info ou all might appreciate.

Fog lights can dimish your depth perception and long distance acuity - how? Because the light refelcts off of the road just ahead, and is picked up by your eye. The pupil contacts more than it would to counteract this, and the resulting pupil contraction actually causes a drop in thge depth of field, just as lens f stop variations affect depth of field.

Something to consider - one reason I hate it when people run their fogs all the time, saying they "see better". You may see to the side better, but baby, it is what's up front that counts.

tgif

Can't do this California. It is illegal.

CH-TLS

Pianoman:

Which relay is the fog light relay? Can it be identified by number, or only by position? I don't have the service manual yet.

I was able to get the same result on an older car by forcing the fog lamp relay closed that was normally open. This relay only closed when the low-beams were on. With the form-C permanently closed, the fogs should work with the marker lights, but based on your comment about the ground path, they won't work with the brights.

pianoman41

There's actually two fog-lamp relays. I'm sure they are both numbered but the service manual labels them by location. The first one is located under the dash in the passenger side footwell and the second is located underhood in the relay/fuse box directly in front of the firewall on the passenger side. The underhood relay is the high-voltage/hi-amperage (20A) relay that does the work of actually powering the lights. The underdash relay powers the switch and checks the headlight switch position to make sure it is in the low-beam only position. You are correct in that both relays are normally open in the off position, but forcing them closed is only half the problem, because the high-beam switch lifts the ground to break the circuit. You definitely don't want to mess with the underhood relay. And all I've done is splice into the circuit between the fog light switch and the underdash relay, in essence forcing it closed whenever the taillights are on (and no highbeams).

CH-TLS

Pianoman:

Thanks for the info. If I can find a couple minutes this weekend, I'll give this a try....uh, before the 40 ouncers.

rock

Rewired my fogs this weekend. Excellent instructions! It took me a while to get the fog switch out. I could barely get my hand under the dash. Once out, the rest was a breeze. I like the way the fogs flash with the parking lights while arming/disarming the alarm.

pianoman41

Remember, they will only do this if you leave the fog light switch in the "on" position when the car is off. If you shut the switch off on the dash, then the parking lights behave as before. A cool feature if you like it, but not required. I don't want to scare people into thinking that they have to do that.

blulegend

A smaller aperture (opening, F-stop, etc.) will increase your depth of field, ie. making everything look more in focus. That is why driving at night is harder because your eyes normally need adjust focus more often depending where you look. However, having more light on the ground decreases your sensitivity to low light objects, ie. people in the street, obstructions, other cars, etc.