Automatic Headlights

I will be installing an automatic headlight module on my 2010 Prius (the DEI 545T). I installed the same one on my 2002 Prius and loved it. It turned the headlights on automatically when it got dark, and when i used the wipers. It also turned them off when I turned the car off.

The module costs about 30 bucks, which I consider a bargain for not having to think about the headlights. I am notorious for forgetting to turn them on.

I remember that the most difficult part of the installation was identifying the correct wires to tap into. Does anyone know where I can get some info on this?

Thanks.

 

Thank your for the info. I have what I need from the site.

In looking over the diagrams, it seems as though automatic headlights is an option on some version of the Prius. The wiring diagrams show a white wire in the headlight switch harness (L47, pin 19) as being the "automatic mode" switch. This wire is brought to ground by the switch to activate "auto" mode.

In checking my harness, I do not have a white wire at pin 19. Now, the other end of that wire is supposed to go to the Main Body ECU in the wiring harness L7A, pin 28.

My question is, do you think the programming is in the ECU already? That is, do we only need to ground pin 28 at the ECU to get autoheadlights to work?

Thoughts?

 

I checked the Toyota techinfo website. The only information i could find was that the sensitivity for the auto-headlights is customizable with the techstream.

I already bought the 545T kit, so I'll probably install it. inlike that it links to the wipers. I do not like that it will requier a seperate sensor (especially beacuase i haven't found a good place to put it).

I also question what the ecu's response would be if you ground that pin via a switch, and then happen to adjust the headlight stalk, in effect, telling it you want the headlights on AND auto headlights on... something the switch itself would be impossible to set. The ecu might be able to handle it, or it could cause a problem.

So I'll probbaly install the $30 kit, but I am very curious about that wire, becuase if that's all it takes, I can't imagie why Toyota wouldn't make it available as a standard option.

 

So I have identified all of the wires that I need to connect, except for one. I need a 12V ignition wire. Something that is 12 volt only when the car is in "ready" mode.

Does anyone know where this can be found (preferably by or to the left of the steering wheel.

Thanks.

 

I opted not to connect it to an ignition wire (since I couldn't find one). I conencted it to a 12-volt source when in accessory or ignition mode. This is not a big deal, especially becuase I am installing an on-off button for the autoheadlights.

There were times on my 2002 when the headlights were automatically on, but i did not want them on. This solves that problem.

However, I am having a problem with finding a generic switch to install in the blank spots. Any ideas? The challange is that the blanks are rounded, so installing a switch into them would not work quite right.

I considered buying an OEM switch (the one that engages the headlight washers). I figured the graphic on it was close enough to serve this function, BUT it occurs to me that it might be a momentary push button. The only other button I saw that I could get OEM was the parking assist button, but that seems momentary too. Can anyone confirm this?

Thanks for your help.

 

I am nearly complete with this mod. If anyone else is interested, I could post instructions. While I was in there, I removed everything else to have a closer look at what's behind the dash. I took plenty of pictures if anyone is interested.

 

First off, I am not a mechanic nor am I qualified in any way to perform auto work. Below is not my advice, but rather a detailed history of what I did. Please use caution with this or any modification, and please do not in any way rely on my information, but rather do your own diligence and proceed at your own risk. Ok, with that understood, I'll start the detailed history of what I did...

PART I - The automatic headlight module

1. Buy the Directed Electronics 545T Nite-Lite System - I bought mine for 35 bucks including shipping. There is a big range of price on these, I've seen $30 to $80 Just look around and buy from a reputable dealer. This module has been around for a long time. I have used it in my 2002 Prius for 7 years and it always worked flawlessly. Pictures of this module, and it's parts can be found in many places on the internet.

2. Prep the module for installation -

a. I only needed one of the two relays. Both relay sockets are connected to the main module with a 3-wire plug. I Removed the relay in the socket with the red and green wires (i didn't want unnecessary clicks and power consumtion). The unused wires can be trimmed and / or removed. the extra socket can be removed by sliding off of the other socket and trimming wires. I opted to do that for ease of installation.

b. the main wire harness contains a lot of wires that will not be used. I trimmed the unused wires as close as I could to the plug, and made sure that no stray wires created a short. I then put a dab of hot glue across the end of the plug where I cut the wires for added reliability. The wires breakdown is as follows:

Violet (12v+Wipers) - To auto turn on the lights when the windsheild wipers are used. This is optional. If you like this feature, keep this wire. If you will not use this feature, it can be removed. I wanted this feature so I kept the wire.

Green (12v-Wipers) - I removed this as it is not used.

Yellow (12V+ ignition) - This wire is needed.

Blue/White (12V- Aux channel) - Normally used to connect to the alarm system to operate headlights from remote. This feature is not available for the Prius security system as no auxillary channels are available. As such, I removed it.

Black (12V - Ground Wire) - This wire is used, so I kept it.

Orange (12V- Ground when Armed) - This is used to flash your headlights when you arm the car. Theoretically it should be possible to implement this feature, but I did not think it was worth the trouble. As such, I removed the wire.

Red (12V constant power) - This wire is used, so I kept it.

c. Note that the module containes a toggle switch. This feature is used to implement daytime running light mode. I did not think this was necessary since if you want daytime running lights, and are willing to turn on a toggle switch, it seems as though you could just put the headlights on using the headlight switch. As such, I did not use it.

d. The remaining piece in the kit is the light sensor. Nothing special about this, just keep it handy.

3. Apply foam tape - Foam tape is not included in the kit, but I got some thin adhesive foam (3M brand) tape and applied to the underside of the main module, the relay socket, and the relay. The purpose of this is to prevent any rattle or buzz when these parts are installed.

Well, that's the end of Part I. In Part II, I'll provide details as to how I began the disassembly of the car. In Part III, I'll discuss how I hooked everything up.

 

First off, I am not a mechanic nor am I qualified in any way to perform auto work. Below is not my advice, but rather a detailed history of what I did. Please use caution with this or any modification, and please do not in any way rely on my information, but rather do your own diligence and proceed at your own risk. Ok, with that understood, I'll start the detailed history of what I did...

PART II - Disassembling the insides of your brand new car

1. Safety First! I removed the negative battery terminal of my accessory battery following the instructions in the owner's manual. (Note that disconnecting this terminal will reset some settings in the car and may require the reinitialization of some features. The manual is very detailed in this regard, so review it so you understand what will happen when you disconnect the battery terminal.)

2. Remove the bottom portion of the steering wheel column cover.

a. Adjust the steering wheel so it is in the upmost position.

b. Push the right side of the lower housing in to disengage the two claws.

c. Do the same for the left side.

d. At the bottom of the hole for the tilt lever, closest to the passenger side, there is a snap that can be removed with your finger and some downward pressure.

e. Rotate the steering wheel so that the top of the wheel is facing the drivers side door. You will see a small rectangular hole in the front of the lower housing. Find something that fits in it and push inward to release the claw.

f. Spin the wheel 180 degrees clockwise and repeat step "e" for the right side.

g. The cover will come right off exposing the headlight wire harness and the wiper wire harness. Remove these harnesses for ease of access by pushing on the little release lever on the plug. Note that the wiper harness is actually two seperate plugs taped together.

3. Remove the inner door sill panel - this is the plastic trim on the floor as you enter in the vehicle, just behind the weather stripping, between the weather stripping and the seat. There are a few clips holding it in. Just pop it out and toward the seat.

4. Remove the driver's side cowl cover. this is the plastic piece that is just to the left of the brake pedal, on the floor. Alternatively, it is the roundy, curvy, plastic piece that touches your left foot when it is on the floor footrest.

a. Remove the plastic retaining nut. It will probably be hand tight.

b. Pull the cover away from the body to remove (mostly toward the passanger seat, but also lift it toward the driver's seat just enough to clear the screw where you removed the nut). The two blue clips may stay stuck in the body. If they do, just pull them out with pliers and snap/slide them back into the cover before reinstalling.

5. Remove the lower instrument panel finish panel assembly - this is the plastic piece that has the controls for the side mirrors on it, as well as the 4 slots for the switches (one of which is the control for the dimmer of the inerior lights).

a. Remove the screw at the bottom closest to the door. It will be exposed when you removed the piece in step 4.

b. There are 6 claws holding it in. Just carefully pull it out. No real trick or angle. I started with the bottomm and when those claws were released, i pulled it back toward the seat.

c. Remove the hood lock cable. While looking up at the white plastic behind the latch (with the back of your head comfortably against the floor of the footwell), you'll see a clip centered in it. You will have to disegage that clip (by pulling it outward) and then slide the whole assembly back (in the direction away from the front of the panel you are removing and toward the brake pedal. It will slide out.

d. Remove the remaining wire harnesses attached to the buttons. If you make sure to depress the release clips on each wire harness plug all the way in, the plug will slide out easily. Do not force it.

6. Technically speaking, there may be more disassembly required based upon where one would decide to place the light sensor. I, for example, put it on the front center dash, behind the instrument cluster, out of sight and with unobstructed access to the sun. I would never actually recommend doing this as removal of the dash requires removing EVERYTHING - from the cup holder to the passenger air bag system, the NAV unit, glove compartment, all trim pices in the front of the dash, the front speakers, a handful of bolts, and the trim pieces over the front portholes, including the ones that expose the side curtain airbags. I only installed it there because I was taking it all out anyway as I wanted to see what was there. (I took some great pictures!) The sensor can be installed in any well lit, unobstructed place. Some locations may require additional dissasembly.

While I won't give advice on where else to install it, as I can't really speak from expereince here, I would say that IF I was not planning on removing the whole dash, then I probably would have installed it on the dash, toward the windshield directly in front of the driver, and just to the right of the front driver's side speaker. In that location, it is mostly out of view of the driver, is unobstructed, and is much easier to install. I will include the steps that I would have taken had i decided to place it there, you know, for informational purposes.

a. Remove the grill covering the speaker. There are 6 clips, 3 on the left and 3 on the right. Using a small screwdriver, I would have sliped it in between the left side where it meets the side wall of the dash. I would NOT have started on the dash side because of the design of the clips. Working in the front most corner of that side, I would have popped out the clip. Force is not a good idea here as you don't want to bend or break the thin grill. Be careful not to scratch the carpeted area by the porthole as it scratches VERY easily. It is not the easiest piece to lift up. It requires some patience. After that first clip or two is up, one would need only slide their finger under it to pop up the remaiing clips exposing the front speaker. (it is a sight by the way!) Be careful not to damage the delicate membrane that covers the speaker.

b. From here, the sensor can be installed just to the RIGHT of the grill, toward the front of the grill, but positioned on the dash itself. There is a crease in the molded plastic of the dash at this point that would hide the tiny black wire well. You may have to gently notch or sand a small grove in the grill or dash to make room for the wire when you reinstall. This notch would need to be VERY small to accomidate the thin wire, so I wouldn't overdo it. Just enough to get everything back nice and flush.

I suppose with additoinal thought, one could figure out an alternative location to put the sensor. Naturally, the alternative location may required some further dissassmbly, or who knows, perhaps none at all. Creativity is key here.

That's it, the disassembly is complete. In Part III, I'll detail how to wire it up.

 

Dash pictures attached!

 

So Everything works great. Below is the last part to how I got auto-headlights.

Part III - Wiring it all up.

1. Decide how I will make the conenctions. Now that I have access to everything, wiring is pretty simple. The first decision I had to make was how to connect the wires. My options were:

a. Buy plastic wire connectors that clip on. The advantage is ease of use. I've also never had one fail. The disadvantage is that the wires are all different diameters. Sizing is important since a clip that is too small could cut a larger wire, and a clip that is too large would make a poor (or worse) intermittant connection. At the very least I would need a multipack.

b. Solder everything up and cover it up with electrical tape. The advantage is a long term permanent conenction. The disadvantage is a more obvious modification to the stock Prius as well as being more difficult and time consuming.

I chose option (a).

2. A word on electrical tape - I would never use cheap $0.99 electrical tape. Not for anything. It has (at best) a temporary adhesion. That being said, even good quality electrical tape tends to want to unstick in extreme temps (the sort you might find in your car on a hot day). I would use it to wrap a bunch of loose wires together (pulling on the tape to give it a SLIGHT stretch as the tape is applied). But I woudl NEVER use it to cover a bare wire or solder connection. For that, heat shrink tubing of the correct diameter is essential. It slips over the xposed wire, and with the heat from a heat gun, hair dryer, or solder iron tip, will shrink and form a snug fit that can handle the vibration and heat of a car. Electrical tape is good to wrap around it, but not in place of it.

3. Below are the wires connection points I made for the main unit of the kit:

Violet (12v+Wipers) - The large white wire in the harness under the wiper switch. Pin 4 of connector L48 (see picture).

Yellow (12V+ ignition) - I didn't use an ignition source becuase I wanted a switch override (that is, an on-off switch for the auto headlight feature). I connected this to the red wire (constant 12V+ wire below). if I didn't want a switch, I would conenct this to a 12V+ ignition wire.

Black (12V - Ground Wire) - I connected this to the bare metal of the car. Used a bit of sand paper to sand a small area of the paint off the chassis under the dash, cimped on a wire connnector, and screwed it in for a good ground connection.

Red (12V constant power) - This would be connected to a 12 volt constant source (like the big white wire going into the body ECU). HOWEVER, I did not do that becuase it really only needs constant power to monitor alarm activity, and I did not use that feature. As such, I connected it (with the yellow wire above) to one side of a switch. the other side of the switch was connected to a 12V+ source when the car was on. I chose the big black wire on the back of the fuses under the dash. I could have chose anything really, including the 12V power receptacle wire.

4. Lastly, i needed to connect the relay. I connected the two wires from the relay to pins 20 and 12 of connector L47 attached to the headlight switch under the steering wheel.

5. I connected the main harness, the relay harness, and the sensor harness to the main auto-headlight ECU from the kit, and attached the kit in the space in front of the main body ECU (by the 4 switches left of the steering wheel). There is a lot of room behind that panel.

That's it. Everythign works and I couldn't be happier.

 

Great questions.

The headlight stalk works the same way and is not disabled in any way. Completely stock functionality.

The systems are parellel. Either the auto headlights will turn them on, or the stalk will. You can turn them both on if you want and it will make no difference.

Think of it this way. You have two wires going into the headlight switch. Turn that switch on, and the headlights go on. All I did was connect a relay fromt he autoheadlight module to those same wires by the headlight stalk. When the relay triggers, it literally connects the same two wires that the headlight stalk switch does.

The relay closes whenever my wipers are on, or when it gets dark out, or when I go in a tunnel or parking garage. Cloudy days do not trigger it.

By the way, I used the same kit on my 2002 Prius, so I have years of experience with this kit.

Disadvantages:

1. You lose control of turning the lights OFF. If you do go in a parking garage, or tunnel, or quickly turn on your wipers (perhaps you just use the wiper fluid and they only go on for one pass) then the autoheadlight module will turn on the headlights. The headlights will of course automatically turn off after 30 seconds of the wipers being off, or exiting the parking garage, or at sunrise, or whatever.

There were times in my 2002 when i didn't want autoheadlights on. I fixed that this time around by incorporating a switch that toggles the power to the autoheadlight module. This is entirely optional, but did fix the problem.

2. There is no way to adjust the sensitivity of the sensor (ie. how dark does it have to be before turning on). This is a little gripe of mine because I feel that it already turns on and off at good light levels. If anything, it it conservative (which is a good thing). For example, during sunset, the lights turn on about 10 minutes earlier then I would normally turn them on. This is not a big deal though.

3. The sensor. I hate the idea of putting a sensor on the dash when I know there is already one there (used for other light sensing things I guess). The one in the kit is the same size, in clear plastic, and I was able to hide it out of sight. nonetheless, it still irks me.

After all of the bad things, let me point out one non-obvious good thing. When the sensor detects a quick change like when I pull into the parking garage (but not when I pass under a tree!) the lights instantly click on. This prevented me from nearly hitting a pedestrian the other day who was dressed darkly on an overcast day. I normally would not have even bothered to put the headlights on, but even if I had, the delay in doing it may have resulted a problem. There is something very satisfying when they click on exactly at the moment you need it.

 

Yes, you missed something!

The dash was removed for informational purposes. My detailed postings list only the parts that have to get removed. They include 4 pieces of trim that all pop out, one philips head screw, and depending on where you put the sensor, one speaker grill cover. Dissassembly would take an inexperienced person 20 to 30 minutes tops. It would take me about 3 minutes to remove the required parts again.

 

Everything went back wonderfully. No parts left over, no scratches dents lose parts, rattle, etc.

I commend Toyota for making the trim pice clips so refined. they pop out well, and go back very tightly. No bent or broken clips.