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This was done on an 04 Ex 5spd, 03-05 should be identical, 06-11 may have different wire colors but locations shouldnt change.
The module I installed is the DEI 545t, and it comes with all the wiring you will need, a photo sensor, and an optional switch for turning the system off. (reverts lights back to manual only operation)
The module has several wires I did not use, which I have addressed at the end of this DIY.
Harness 1 (big harness) will have 4 wires used, the rest were removed from the harness to make install cleaner. Note: I did not use the Wiper activation wire, which is why it is not pictured below.
BLACK: This wire goes directly to ground, so secure it to a solid bare metal bracket under the dash.
RED: This fused wire goes to a constant 12v source, I used the large white wire in the main ignition harness.
YELLOW: This wire goes to a 12v switched ignition source, I used the large Black/Yellow wire in the main ignition harness.
GREEN: This is the negative wiper input trigger, and will need to be diode isolated between the low & high speed wiper settings which will be a Blue wire (low) and Blue/Yellow wire (high). Both can be found in the main ignition harness, and will be small gauge wires.
Found Here
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Harness 2 (3pin harness) goes from the module to a dual relay pack, which you do not need. Cut the 3 wires as close to the relay pack as you want, and only 2 of these wires will be used. The red wire will not be used and can be removed from harness. So all of that huge mess of wiring is now only 2 small wires, how cool is that?
BLUE: This wire goes to the parking light wire in the OEM alarm wiring harness, which is also solid blue.
GREEN: This wire goes to the headlight wire in the OEM alarm wiring harness, which is Blue/Red and right next to the parking light wire.
Found Here
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Photo Sensor The photo sensor is a small clear piece with a long 2 wire lead & a small plug at the end. Clean a part of the dash with isopropyl alcohol for the double sided tape to grab onto. The placement is not a huge deal, I placed mine right at the base of the windshield. The black square is an alarm indicator, I set the photo sensor next to it so it would not be in its shadow at all. I removed the A pillar and ran the wire down into the dash from there, and it just plugs into the DEI module.
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Wire removal.
On the bottom of the plug you will see the contacts, with a razor blade or small flathead press the pin's small metal tab into the plug and the wire can then be pulled out from the back of the plug.
Plug bottom:
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Finished Result: All of the unused wires are now out of your way.
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Things Omitted:
1. Toggle Switch I chose to leave out the toggle switch, because I do not see a time I would ever want to turn off the auto feature. You can always override the sensor by manually turning on the headlights at anytime, just remember you will have to turn them off again manually too.
2. Alarm Options The orange wire would be needed if the nite-light option is used along with an alarm. This allows the alarm to flash the parking lights when arming, however the module itself flashes the parking lights constantly while the nite-light feature remains on (really stupid). For this reason I turn the nite-light off by turning the dial inside the module completely counter-clockwise. The other alarm wire is an auxiliary activation option, so an alarm could turn on the headlights via remote control. I wasnt interested in that, so I left it out.
3. Daytime Running Lights (DRL) I do not care for DRLs, Id rather have my headlights last longer & not be on while starting my car. Out of the box this option is activated, to deactivate DRLs you need to open the module (4 Philips screws on the back) and cut a red wire that connects two points together on the circuit board. Sorry no pic, but its pretty obvious. I cut the wire out on both ends, so there would be no chance of a wire end shorting against something. If you want DRLs, then just skip this step.
Finished Result:
One small sensor and a whopping 6 wires, and its all done.
My headlights & parking lights will now auto activate when the photo sensor sees it is getting dark, or if I drive into a parking garage (which I do quite often), or a tunnel. It has a timed turn-on delay of 5 sec so small shadows wont activate the headlights, and there is a 30 sec turn-off delay so headlights are not just turning on & off when you pass a bright light or oncoming car. I leave the house pretty early in the morning sometimes & there are many times I need headlights, but then by the time I get to school or work its light enough that I forgot the headlights were even on. No more annoying beep and no more dead batteries because the headlights will turn off when it gets lighter out &/or when I turn off the ignition. (my old del Sol didnt have a warning buzzer) All of that is well worth the little time it took to install, and the small price for the module.
The module I installed is the DEI 545t, and it comes with all the wiring you will need, a photo sensor, and an optional switch for turning the system off. (reverts lights back to manual only operation)
The module has several wires I did not use, which I have addressed at the end of this DIY.
Harness 1 (big harness) will have 4 wires used, the rest were removed from the harness to make install cleaner. Note: I did not use the Wiper activation wire, which is why it is not pictured below.
BLACK: This wire goes directly to ground, so secure it to a solid bare metal bracket under the dash.
RED: This fused wire goes to a constant 12v source, I used the large white wire in the main ignition harness.
YELLOW: This wire goes to a 12v switched ignition source, I used the large Black/Yellow wire in the main ignition harness.
GREEN: This is the negative wiper input trigger, and will need to be diode isolated between the low & high speed wiper settings which will be a Blue wire (low) and Blue/Yellow wire (high). Both can be found in the main ignition harness, and will be small gauge wires.
Found Here
Harness 2 (3pin harness) goes from the module to a dual relay pack, which you do not need. Cut the 3 wires as close to the relay pack as you want, and only 2 of these wires will be used. The red wire will not be used and can be removed from harness. So all of that huge mess of wiring is now only 2 small wires, how cool is that?
BLUE: This wire goes to the parking light wire in the OEM alarm wiring harness, which is also solid blue.
GREEN: This wire goes to the headlight wire in the OEM alarm wiring harness, which is Blue/Red and right next to the parking light wire.
Found Here
Photo Sensor The photo sensor is a small clear piece with a long 2 wire lead & a small plug at the end. Clean a part of the dash with isopropyl alcohol for the double sided tape to grab onto. The placement is not a huge deal, I placed mine right at the base of the windshield. The black square is an alarm indicator, I set the photo sensor next to it so it would not be in its shadow at all. I removed the A pillar and ran the wire down into the dash from there, and it just plugs into the DEI module.
Wire removal.
On the bottom of the plug you will see the contacts, with a razor blade or small flathead press the pin's small metal tab into the plug and the wire can then be pulled out from the back of the plug.
Plug bottom:
Finished Result: All of the unused wires are now out of your way.
Things Omitted:
1. Toggle Switch I chose to leave out the toggle switch, because I do not see a time I would ever want to turn off the auto feature. You can always override the sensor by manually turning on the headlights at anytime, just remember you will have to turn them off again manually too.
2. Alarm Options The orange wire would be needed if the nite-light option is used along with an alarm. This allows the alarm to flash the parking lights when arming, however the module itself flashes the parking lights constantly while the nite-light feature remains on (really stupid). For this reason I turn the nite-light off by turning the dial inside the module completely counter-clockwise. The other alarm wire is an auxiliary activation option, so an alarm could turn on the headlights via remote control. I wasnt interested in that, so I left it out.
3. Daytime Running Lights (DRL) I do not care for DRLs, Id rather have my headlights last longer & not be on while starting my car. Out of the box this option is activated, to deactivate DRLs you need to open the module (4 Philips screws on the back) and cut a red wire that connects two points together on the circuit board. Sorry no pic, but its pretty obvious. I cut the wire out on both ends, so there would be no chance of a wire end shorting against something. If you want DRLs, then just skip this step.
Finished Result:
One small sensor and a whopping 6 wires, and its all done.
My headlights & parking lights will now auto activate when the photo sensor sees it is getting dark, or if I drive into a parking garage (which I do quite often), or a tunnel. It has a timed turn-on delay of 5 sec so small shadows wont activate the headlights, and there is a 30 sec turn-off delay so headlights are not just turning on & off when you pass a bright light or oncoming car. I leave the house pretty early in the morning sometimes & there are many times I need headlights, but then by the time I get to school or work its light enough that I forgot the headlights were even on. No more annoying beep and no more dead batteries because the headlights will turn off when it gets lighter out &/or when I turn off the ignition. (my old del Sol didnt have a warning buzzer) All of that is well worth the little time it took to install, and the small price for the module.
