Joe

How do you rewire the stock foglights on a 95 Max?

MAXDriver

You mean rewire fog lights to come on with parking light?
This is off MAXFAQs courtesy of Andi.

Q: The foglights on my 95+ Maxima will only turn on when the lowbeam headlights are on. How
can I get them to run with just the parking lights?

A: Andi has provided a step-by-step procedure.

For some reason (probably a DOT regulation of some sort), Nissan decided to make the foglights only
turn on when you have the headlights on. And the fogs turn off when you use the highbeams!

The following steps will result in the following behavior from the foglights: The foglights will turn on
with the foglight switch whenever the parking lights, the lowbeams, or the highbeams are on. Only
when the headlight switch is on the full "OFF" position will the fogs be off independent of the foglight
switch.

So... before I explain how to rewire the foglights to get them to run in the above manner I will give a
brief summary of Nissan's foglight circuit so you can have a better understanding of what you're
working on:

Actual Stock wiring: The foglight circuit goes through a regular relay with one power
input, one signal input, and the output (and a ground, I think). Here's Nissan's clever
trick: The signal input does *NOT* come from the foglight switch! It comes from the
lowbeams' +12V. Then, you ask, how does the foglight switch affect the foglights? The
foglight switch on the turn signal stalk COMPLETES THE CIRCUIT BY PROVIDING A
GROUND. Neato huh? So *only* when the lowbeams are on can the foglights run.

[A relay is defined as a unit with a power input, a signal input, and a
power output. When there is no voltage in the signal input, the power
input and power output are DISconnected. When there is a voltage on
the signal input, the relay connects the power wires, sending power to
the power output (from the power input). For any computer science
majors out there: Think of a relay as a great big "and" gate.]

Here's what you're looking for -- the step-by-step procedure to rewire the foglights to behave as
described above:

[All directions will be referenced how you see it when looking at it, not
absolute sides of the car. i.e. when you have the hood open and you're
looking at the engine, the steering column (in the US) is on the RIGHT!]

1.Locate the relay box on the left side of the engine bay, which is in front of the strut tower. On
the lid of this box you will see items such as "CORN LIGHT", "FR FOG LIGHT", and "AIR
CON".
2.Right in front of this box is the coolant reservoir. It is held to the fender with two 10 mm hex
bolts. Remove the bolts and pull the coolant reservoir away from the fender. We need to
temporarily relocate this reservoir because we'll need this space to work on the wiring. I
suggest you lean the reservoir on the radiator between it and the engine block... It fits there
quite well without falling and making a mess :-)
3.Open the relay box. This is really easy. Standing on the [absolute] right side of the car in front
of the RF wheel, pull up on the right side of the lid on that little latch.
4.You will need to remove the two relays on the far right and the relay on the far left to be able to
remove the bolts holding the relay box to the chassis. To do this, you will notice that each
relay is held down with a little clip, which is on the side of the relay facing the engine block.
Using a flathead screwdriver, pull that clip away from each of the aforementioned three relays
and pull the relay up. These relays *should* be identical but you never know, so remember
which relay is from which location and put them back in the same locations.
5.Remove the two bolts holding the relay box to the chassis. There's also a "leg" holding the
relay box to the wheelwell protrusion, under where the coolant reservoir usually is. (Aren't you
glad you removed it?). Pull up on this arm, jiggling it sideways in the process to help it come
out.
6.Now look at the sides of the relay box. You will notice that the relay box is actually two pieces
held together -- like a Rubbermaid microwaveable box... the lid comes off. In this case, the lid is
the "Grill" that holds all the relays in place. You will notice on the sides of the relay box that
there are fasteners holding the lid on. If memory serves me correctly, there are three on each of
the long sides and two on each of the short sides. Unfasten them all.
7.At this point, you would expect the relay box to open, but it won't. There are two more clips to
unlatch. These clips are on the outboard side of the relay box on the top edge. They're
between the bolt-arms that connect to the chassis, and they're very insignificant-looking, just
sticking upward in a hole. (Keep your minds out of the gutter, guys). While pulling the lid up
from the opposite side (which is already "open"), push each of these clips towards the middle
of the relay box. You will hear a click and the side you just unclipped will come free.
8.Pull the lid upwards, exposing the undersides of all the relays. Lots of wires, eh? Now find the
original TOP lid of the relay box, which has all the labels of the relays. You will notice that the
fog light relay is the top right, when looking from above. This is one of the relays you removed
to get to the bolt holding the relay box to the chassis.
9.Turn on the headlights and whip out your sharp-needled voltage light. Poke the terminals of
the fog light relay connector with it -- make sure that the left (when looking at it from above
from the absolute right side of the car) connector has +12V. There will also be another terminal
with +12V, but the left one is the important one. If the left one does not show +12V with the
headlights on, then something's drastically different with your car. If that is the case, please
email me at Andi@airmail.net to notify me of this. Also, If there is anything else in this
document that contradicts your car's characteristics, please stop and email me.
10.Assuming that Step 9 showed the left terminal to have +12V, flip over the relay-holder grill and
look at the underside of the fog light relay holder. Remember, we've flipped it so what was the
left terminal is now the right terminal -- i.e. the terminal on the closer to the center of the relay
box. This is the signal terminal. There should be a green/yellow-striped wire leading to this
terminal. (There might also be a different green wire going to another terminal -- ignore that
one).
11.Tug on the green/yellow-striped wire leading to the signal terminal to get a decent length of it
to do surgery on. Cut the wire. Wrap the end coming from below with electrical tape so as not
to cause a fire hazard... You don't want a +12V wire hanging naked in the relay box do you?
Now connect a long (I'd say three foot), well-insulated, thick wire to the end of the wire
hanging from the relay. I don't know which method is best... I used one of those plastic
thingees that takes two wires and stabs them with a piece of metal, which conducts the
electricity. I then wrapped this well with electrical tape so as not to cause the aforementioned
fire hazard.
12.Find the best route for this wire to exit the relay box. Maybe you could drill a nice small hole in
the bottom of the relay box? Here's what I did: route this wire over the right edge of the bottom
part of the relay box. Then put the grill back on... You'll notice a perfectly-sized gap between
the walls for the wire. Fasten all the clips of the relay box's grill's lid and squeeze the two
together well to get all the clips tight. This is especially important for those two hidden clips
that held the box at the last part of the opening procedure... remember?
13.Put the relay box back in its original position and fasten it's leg back to the wheelwell
protrusion by just pushing it down into the hole. Then use the two bolts to fasten the box's
arms back onto the chassis.
14.Put the three relays you removed at the beginning back into the relay box in their original
positions. Put the cover (the one with the labels) back on the relay box.
15.Optional: to test the setup: turn on the foglight switch and leave the headlights off. Extend the
new wire coming out of the relay box over the engine and touch it to the battery's positive
battery terminal. The foglights should turn on. Why? This is the signal wire for the foglights --
whenever this wire has +12V *and* the foglight switch is on, the fogs should turn on. We will
now connect this signal wire to the side marker light in the bumper -- that way, whenever either
the parking lights or the headlights are on, the fogs will have the signal to run -- i.e. they will
have "permission" to turn on according to the foglight switch.
16.Gently pry off the right front side marker lamp using a flathead screwdriver wrapped in a clean
cloth. Disconnect the wire coming from behind it. Put the side marker light itself away for a
minute as it's the WIRES that we're concerned with. [Note: you might want to unscrew and
disconnect the turn signal as well to be able to pull the wire farther out.]
17.Route the new wire coming out of the relay box through the fender to the side marker light.
This is easier than it sounds -- right below the relay box there's a very large hole in the inner
fender. You can literally fit your arm into it (take your watch off first) and just push it all the
way through. Then find it through the side marker's hole in the bumper and pull it out. Then
remount the coolant reservoir back in its original position.
18.Right behind the wiring harness for the side marker light, there's two wires that immediately
hide inside an accordian-type protection tube. Cut enough of this tube off (about an inch...) so
that you can splice the new wire from the relay box to the red/blue-striped wire coming from the
wiring harness. Now splice the new wire to this red/blue-striped wire. I used the same method
as in the relay box. Don't forget to "terminate" or cover the end of the new wire with electrical
tape if it doesn't end inside the splicing instrument. Electrical tape is your friend.
19.Connect and reinstall the turn signal and side marker light in the bumper.
20.Finished. Now test the new setup by turning on the parking lights and enabling the foglight
switch. Then turn on the headlights and blink the highbeams... foglights should remain on.

Joe

Hey thanks. I didn't know it was in the FAQs.
I'm gonna try it tomorrow. Wish me luck.