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DISCLAIMER: This modification may void some or all of your warranty, just like any other modification. Although it is completely removable, it remains your own responsibility if anything goes wrong. Read through the whole walkthrough before starting.

This mod will work regardless of whether you have automatic headlights or not.
It will also work with automatic wipers or normal ones.

Depending on your setup, this is how it works:

1. Auto Wipers and Auto Headlights:
With the light switch in ANY position and the Wipers placed in AUTO, the parking lights and headlights will come on.
The lights will go off when the wipers are placed in OFF or when the ignition is in the ACC or OFF position.

2. Normal Wipers and Normal Headlights:
With the light switch in ANY position and the Wipers placed in either SLOW or FAST, the parking lights and headlights will come on.
The lights will go off when the wipers are placed in OFF or when the ignition is in the ACC or OFF position.

Skip to the end of the walkthrough for more information on exactly how the MOD works.

Why would anyone want this?
1. In some countries (like mine) it is law to have your headlights on when it is raining. I.e. one less thing to switch on and off again later.

2. If you have auto headlights they don’t always turn on when it is raining during the day (still too bright). Now when placing the wipers in AUTO they will come on.

For whom will this NOT work?
If you always have your Auto wipers in AUTO position, you’re lights will always be on if the Ignition is ON.
(I never leave my wiper setting in AUTO if it’s not raining, because it scares the sh!t out of the guy washing the windscreen at the service station 

What will this modification cost?
Should not be more than $6 US for all the parts needed.

Is this modification reversible?
Yes. Completely. All wires are connected directly into connectors and can be pulled out easily.

What do you need to buy?
1. 2 x 4148 diodes
2. 1 x 12V Relay (I used a NT72-2C-S10 relay, there are many equivalents. It’s only important that the relay closes when 12V is
applied and opens when it is removed)
3. Wiring – Approximately 3 ft of 2.5mm Flex should do
4. 5 x any suitable crimp terminals (0.1 inch Molex Female Crimp Terminals or equivalent. If you can’t find any you can cut a needle
in half and use the head part.)

4148 diodes:

12V Relay:


Crimp Terminals:
(I cut the terminal’s end to a sharp point)

Or a needle soldered on:

What else do you need?
1. Soldering Iron and solder
2. Wire stripper or Knife
3. Philips Screwdriver
4. Optional : Multimeter

How long will this take?
For someone with very little experience in electronics or modifications: Approximately 1 to 2 hours.

The walkthrough:

STEP 1. Preparation.
Cut wire into following lengths:
4 x 3.5” lengths
2 x 6” length

Use the 4 shorter pieces and solder them into the relay in the following manner.

The topmost pin on the relay is left open.
A and B is used to open and close the relay. To do this 12V switched power from the wiper stalk is used as well as ground. (Can be wired either way).
C is the signal wire from the wipers (Auto or On).
D goes to the diodes and then to the Lights.

Solder in the two diodes to the D-wire. VERY NB: The sides on the diodes with the thick black lines (cathode ends) must be used here. Both diodes are connected to the D-wire.

Now solder the two longer (6”) wires to the other side (anode ends) of the diodes. These wires must not touch each other.

Fix crimp terminals to the five ends of the wires. (A, B, C, E, F).
(See pictures above.)
NOTE: If you are unsure of the size of your crimp terminals continue to Step 2 and have a look at where the wires will be connected to get an idea of what you need.

Insulate the wires around the diodes. (If you used needles and soldering, you might need extra insulation near the tips of the wires to prevent them from making contact with each other after they are inserted into the car’s connectors.)

And you’re finished with Step 1. (Tape measure in inches)

STEP 2. Remove covers and screws.

Drop your steering column all the way down to make more space.
Remove the rubber cover from the top steering wheel cover. Do this by hand.
The cover does not come out completely. Just separate it from the plastic cover.

Remove the plastic cover from the top of the steering wheel. It clips in on the sides. Use your hands to firmly pull up on the cover starting at one of the back corners of the panel. Completely remove the panel and set it aside.

Remove the two screws holding the bottom plastic cover with a Phillips screwdriver.

Slide the bottom plastic cover gently down over the ignition plate. Do not remove the cover. Only slide it down enough to expose the screws on the wiper and light stalks.

Remove the two screws on the wiper stalk. Then gently pull the stalk out and let it hang loose.

Repeat the same for the Lights stalk.

STEP 3 Connecting the wiring harness

I placed the relay in the following position and used a bit of Prestik to keep it from rattling:

Now for the important part – connecting the wires:
When inserting the crimp terminals into the connectors, make sure you find a fairly tight fit. Look into the connector to see what side of the existing wire you can insert the terminal into.

Wiper Stalk Side:
Connect wire A to the Green/Orange wire (Switched 12V: 12V with Ignition ON, 0V with Ignition OFF)
In picture: Top row, Second from Right.
Connect wire B to the Black wire (Ground)
In picture: Bottom row, Far Right.

The connection of wire C depends on whether you have AUTO Wipers or not.
For AUTO Wipers:
Connect wire C to the White/Green wire. In picture above: Top row, second wire from Left.
For Normal Wipers:
Connect wire C to the Black/Green wire.

Lights Stalk
Now take the long wire (with the diodes) to the other side to the lights stalk.
Connect the one wire to the Black/White wire (Parking lights)
Connect the other wire to the Black/Green wire (Headlights)

Make sure all connections are fairly tight and that none of the wires are touching each other.

STEP 4 Reassembling
(You may want to check operation of the lights and wipers before reassembling. If doing this remember to lift the wipers off the windshield before operating them. It is quite difficult to use the stalks when they are hanging loose. Either use two hands or replace them into their slots first)

Replace the stalks into their slots.
Make sure all your wire connections are still in place.
Replace the four screws for the stalks.
Push the bottom plastic cover back up and replace the two screws at the bottom.
Replace the top plastic cover starting with the two rear clips.
Replace the rubber cover into the top plastic cover.
Return the steering wheel to its original position.
Clean up any marks left and remove all tools from your car.
Test that all is functioning as described.

Happy motoring!

Technical Specifications

(I’m not a technician, so please bear with the layman’s explanation)

The wire used on the wiper stalk (Green/White for AUTO and Black/Green for Normal) works as follows: When ignition is ON and the wipers are OFF there is a 12V current in this wire. When the wipers are turned ON this wire is earthed and the voltage drops to 0V. This sends a signal to a control unit that then turn the wipers on.

On the lights stalk the wires for the parking lights (Black/White) and headlights (Black/Green) works in the same way, except the 12V current in these wires are always there when the lights are off, even with the keys removed.

If you would connect a wire between the two stalks without a diode, the wipers would turn on the lights, but the lights will also turn on the wipers. A diode is therefore used as a one way gate to ensure the lights will not influence the wipers. Two diodes are used because the parking lights and headlights must both be activated (they each have their own wire).

So with the wiper wire connected through two diodes to the lights the following happens:
Lights are OFF therefore the current in the light wires are 12V.
With ignition ON and wipers OFF, the current in the wiper wire are also 12V.
If you switch on the wipers now, the voltage in the wiper wire are pulled to 0V and the connection through the diodes pulls the light wires’ voltage also down to 0V, signaling the control unit to turn the lights on.
If you switch the wipers OFF the voltage in the wiper wire returns to 12V and this is send through the diodes to the light wires as well returning the light wires’ voltage to 12V and therefore switching off the lights.

What is the relay for then?
There is a glitch with the above system: When you switch the wipers on the voltage in the lights are pulled to 0V thus turning the lights on. If you now leave the wipers in the ON position and turn the ignition OFF the voltage in the wiper wire stays at 0V and therefore the voltage in the light wires also stay at 0V. This means that even if the lights are switched OFF and the keys removed, the lights will stay on! To get them off again you must switch ignition ON and turn the wipers OFF.
The easy way to correct this problem is with the relay. It gets it power from the switched 12V wire on wiper stalk and the Ground wire. This means that the relay closes (allows power through) when ignition is ON, but cuts flow when ignition is OFF. So with the relay installed the diode wires are completely disconnected when the ignition is OFF and the whole system works normally.
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