Ignition Switched Headlights

This is a modification I did may years ago (circa 2004), but I thought I should detail it here, as it comes up now and again.  There are other options available, such as Houston's new headlight switch that includes this functionality, and aftermarket solutions that can switch the lights on only in the dark and when the wipers are on, but I like to do things myself.  This mod only requires some wire, connectors and a relay and socket.

Since I did this so long ago, I don't have any pictures of the installation, so it's just text for now.

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I kept forgetting to turn my headlights off when I got out of the car, since there's no buzzer or anything to warn you about it (there is, but mine never worked), so I  added a relay to the headlight switch to do it for me when the ignition is off. Now I just leave my lights on all the time, even during the day.

Parts

• Pre-wired relay socket
• Relay
• Method to connect the relay to headlight switch wiring, which could be:
  • Male and female blade-style connectors and a crimp tool
  • Butt connectors and a crimp tool
• Wire to run from the relay compartment to the new relay
• Optional: Inline fuse holder and fuse

or:

• DeLorean Parts NW's Headlight Switch Safety Bypass Kit, which uses all the same parts and doesn't require a crimp tool. It's only $10,  and has everything you need. http://www.delorean-parts.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=DPNW&Product_Code=K3003DP&Category_Code=9450

POWER PROBE OR MULTIMETER

I also really like the Power Probe, which is a simple electrical test tool for automotive work (you can probably find older models on eBay for cheaper than a new one, and it'll do the job just as well with a few less bells and whistles).

Once connected to the car's battery, you can touch any electrical connection and tell if it is positive or negative via an LED an optional buzzer (the newer models have screens that show you the voltage as well). Furthermore, you can test  circuits (and, if you're reckless, blow fuses) by applying positive and negative via a switch on the probe.

I have a Power Probe II. It's very handy for finding, say, ignition-switched wires, or seeing if a circuit has power, or making sure a circuit works when you apply 12v or ground to it, and so on. If you plan on doing a lot of electrical work, I recommend it; if you're just doing one or two
things, you can just get away with a multimeter.

LABELING

I've also taken to using a label printer to thoroughly document any new wires I add to the car, so that I'll know what the heck I did when I look at it in the future. I got a portable Brother label printer, and it works great.  You can just use some masking tape and a pen if you like.

RELAYS AND SOCKETS

You can get the relays and sockets from various sources. They usually come with wires already attached. Any standard automotive relay will do. Google lists a bunch of both, and I'm sure you  can find all of these parts locally easily enough.  As mentioned above, the DeLorean Parts NW Headlight Switch Safety Bypass kit also includes everything you need to do this (just order two of them, one for the safety and one for the mod).

Installation

I chose to do this from the headlight switch. You can probably do it  from the fuse box behind the passenger's seat, but I knew that everything went through that switch and decided that was the route I would take.

The hardest part is probably accessing the headlight switch and fitting everything behind the console without getting in the way of the heater wires.  Running the wires from the relay compartment isn't too difficult.

ACCESSING THE HEADLIGHT SWITCH WIRING

There are a few ways to get access to the back of the headlight switch.

METHOD 1: REACHING BEHIND THE CONSOLE

I did the method that didn't require taking apart the center console, which involves reaching behind the console from the driver's side and unplugging the connector from the headlight switch. This is pretty annoying to do and you cant see what you're doing, and it's a bit of a pain to reconnect the switch to the plug, but it's not too horribly bad.

METHOD 2: REMOVING THE FACE PLATE

The second method is to remove the headlight switch itself. I recently installed DeLorean Parts NW's headlight switch safety bypass, and his instructions work well in this situation. First you remove the three climate control knobs, and then the long screw behind the center knob. You can then pull out the face plate and wiggle the headlight switch out of its socket, pulling the wiring through with it. I'd suggest getting the safety bypass and doing both installations at the same time.

METHOD 3: REMOVING THE RADIO

A third method might be easier if you already have an after market radio, and is what I did while I was also replacing the rubber cowling on my center air vents and installing the above headlight switch safety bypass.

I've removed my radio so many times that it is mostly held in by pressure from the metal mounting cage rather than those bent metal clips, so it's easy for me to remove. I used two coat hangers bent 90 degrees at the end to release the clips that secure my Sony stereo to the cage so I could pull it out and unplug it. I also removed the metal frame that holds the stereo in place, which gave me excellent access to the headlight switch wiring. This might be a lot of work for some people, and I have no idea what's involved with the stock radio, so you might just want to go with the first or second methods instead.

Wiring

Hooking everything up is fairly straight-forward. As usual, you'll want to disconnect the battery before you proceed, since some of these wires are live even when the car is off. 

You need to insert a relay between the headlights and switch. I used butt connectors, but you can do whatever you're comfortable with. The DeLorean Parts NW headlight switch safety bypass kit uses T-taps and avoids the need to use a crimp tool, but a crimp tool will give you better connections.  The choice is up to you.

If you do use DMC Parts NW's kit, you would do the following:

First, pull the headlight switch's connector out far enough that you can get to the wiring.

1. The Blue/Brown wire actually powers the headlights, and it is this that the relay will switch. Install two T-taps about an inch apart on the Blue/Brown wire, then cut the wire between the T-taps.
2. Connect the relay socket's Blue wire to one of the T-taps on the Blue/Brown wire.
3. Connect the relay socket's Yellow wire to the other T-tap on the Blue/Brown wire.
4. Install a T-tap on the Black wire on the headlight connector. We use this to provide ground to our relay.
5. Connect the relay socket's White wire to the T-tap on the Black wire.
6. Locate an "accessory" wire. This is a wire that is live only when the key is in the "run" position. I actually ran a wire from the relay/fuse compartment from behind the passenger seat to the number #35 relay ("Aux Relay -- Accessory Position -- 1") in the fuse and relay diagram in the Workshop Manual section M:07:02. You're looking for a wire that is reads positive only when the key is in the "run" state; you should be able to easily find this via a multimeter or PowerProbe. It is very likely that there is such a wire under the dash, but I'm not sure where at the moment.
7. Connect a T-tap to the "accessory" wire. This will energize the relay when the key is set to "run".
8. Attach the relay socket's Black wire to the the T-tap on the "accessory" wire.
9. Put a relay into the relay socket.

The middle wire on the relay socket is unused in this application,  and has been removed on DMC Parts NW's kit.

RELAY SOCKET PLACEMENT

I recommend keeping the relay socket's wires at their full length. You can then stuff the relay and socket through the headlight switch's hole and get it out of the way so it doesn't interfere with anything else. I pushed mine toward the back of the car and down to the left towards the driver's side. You can probably reach around the back of the center console from the left side and pull it through enough that it's out of the way.

Be careful not to block the temperature knob with the relay. At first, I inadvertently jammed the temp knob by placing the relay to the left of it, thus blocking the arm from moving to the left and keeping me from turning the heat up beyond the middle setting. You might want to turn that knob all the way to "hot" before positioning the relay, and making sure that the knob still has its full range before putting everything back together.

You can optionally install an inline fuse in this setup. I put one between the relay's Black wire and the "accessory" between steps 7 and 8.

Testing and Operation

That's it for the wiring. To make sure it works, plug the headlight switch back into the socket, set it to the "off" state, and reconnect the battery.

Since the car is off and the headlight switch is off, the headlights should also be off. Push the headlight switch through the parking light position, the "on" position, and back to the "off" position; the headlights should remain off the entire time.

Now put the key in the ignition and turn it to the "run" position (you don't need to start the car). Since the headlight switch is off, the headlights should also be off. Push the button once and make sure the marker lights are on. Push it a second time and make sure the headlights are on.

If you turn the car off now, the headlights should also go off. If you start the car, the headlights should turn off while the car is cranking, and come back on when the key returns to the "run" position.

You can now leave the headlight switch in the "on" position all the time, and never have to worry about forgetting to turn your headlights off again.

Re-Assembling the Center Console:

To put the console back together, you simply need to snap the headlight switch back into place, put back on the face plate, replace the screw near the center knob, and put the knobs back on their respective switches.

All Done

The total cost of this project is under $10, if you get everything locally or already have the parts lying around, and $10+shipping if you just repurpose the DeLorean Parts NW Headlight Bypass Kit. I've run with this for a years now and never had any problems, and I don't have to worry about forgetting to turn off my lights anymore.