Automatic Headlights

Hawkmoon,

I would like to wire the car so the headlights come on automatically when the vehicle is on. Without a light sensor. Could I connect the big black wire (accessory power) to the pins 20 and 12 of connect L47? Basically to bypass the switch?

Thank you for any ideas

 

There hasn't been a posting yet for the part number of the Canada stalk, which has the "Auto" position. I will try to get that info from the dealer and post it.

 

Ummm... maybe I'm missing something... can't you just turn on the headlights and leave them on? They turn off automatically when you shut off the car, so if you want them always on, just rotate the stalk switch to the on position and leave it there. Right?

 

Doh! You're totally right

(I'm embarrassed now!)

 

Well, I finished the Auto Headlight mod using factory circuits. It works great!

I did need to remove the entire top of the dash to get to the needed connection for the light sensor signal. You need to connect at the light sensor itself (the little "button " on top of the dash on the passenger side). There is no wire at that connector for the pin needed, so I had to improvise a pin (from a computer CD drive audio wire harness) and run a separate wire all the way to the ECU's L7 connector (which wasn't that tough). I scavenged a couple more pins from my useless L8 connector for the two pins that needed to be added to L7 (one from sensor, one to be from a new headlight stalk). So my L8 connector gave its life for this mod.....And, one more scavenge from yet another unused connector (for the sunroof, which I don't have) for the headlight stalk connector (L47). But you could probably order all of the pins that I scavenged and make it easy (but costly) on yourself...

Disassembly of the dash was definitely the toughest part, but very do-able, if you've taken some dashboards apart before. I will post photos and a write-up soon.

 

OK, as others have posted as well, the usual disclaimer applies: I’m not recommending this, just describing what I have done. Everyone’s skill and comfort level is different with taking apart their entire dash… That having been said:

The goal of this mod was to add true auto on/off headlights using only the existing (installed) factory circuits, with the exception of adding or replacing:
- One added wire from the light sensor at the top of the dash, to the ECU L7 connector
- A replacement Canadian headlight stalk switch with the "Auto" switch position
- Add one wire from the headlight stalk switch connector to the Main Body ECU at connector L7

I chose to get the Canada stalk that also has the fog light switch, since I was also installing fog lights and using the factory circuits. That mod is covered in the Technical Discussion forum. The part numbers for the Canada Stalks:
With fog lights: 84140-07141
Without fog lights: 84140-47120

This mod also only applies to a Prius IV, with Nav, with no sunroof. I do not know whether other configurations affect which wires are present and missing. For example, perhaps the sensor wire is run on the advanced technology package on a V - but I have no way of knowing. The wiring diagrams often don't identify which wires are present or missing.

I would also strongly advise anyone attempting this mod purchase at least a 2-day subscription to TIS (techinfo.toyota.com) so that you can download or view the dash disassembly instructions as you go. While not that difficult, it really helps to understand the direction to pull things apart. The entire dash disassembles removing less than a dozen bolts - the rest are plastic retaining clips, which can get permanently bent if you're pulling the wrong way too hard. The good news is if you are reasonably careful, the whole thing goes back together beautifully and quickly.

1. I started by disassembling the dashboard using the TIS instructions for removing the "Upper Instrument Panel". Note that the first step in this process is disconnecting the negative terminal from the auxiliary battery in the luggage compartment, and waiting 15 minutes or so for the entire system to discharge. You're going to be messing with wiring for the SRS (airbags), so DO NOT attempt this without disconnecting the battery and waiting.

2. Most of the dash panels come off with very little force. Hawkmoon77 has written a great explanation of this process earlier in this thread - I won't repeat it. The one area that I found a bit tricky was removal of the fuzzy "pillar covers" that cover the side curtain airbags and are over the small triangular windows on each side. Once you have them free across the top and on the bottom end closest to you, you need to carefully lift the forward end while tilting the back end downward, pulling out the front-most retaining tabs. Be careful as you take these off. The curtain airbags are right behind these, and one small puncture and the airbag is history. Toyota recommends taping cloth over the airbag after the pillar cover is off, in order to protect them. Not a bad idea. (Make sure you remove it again when you reassemble!)

3. Once you have the top instrument panel removed, set it upside down on something soft so that you can work on it easily. (Note that I didn't remove the speakers. I didn't find it necessary.) Photo #1 shows this. The circled item is the light sensor and connector, into which you need to insert a new wire.

4. The connector pin that is needed for this I1 connector, pin 4, is 82998-12750. Since I didn't feel like waiting, nor paying Toyota $7.00 or so for a 20 cent pin, I made one. After looking at a whole bunch of computer connectors I had lying around, I found one that was pretty close: There is a cable that is used inside computers to connect the CD/DVD drive audio out to the motherboard. That connector is generally black and has 3 wires coming out of it, which go to a round cable. I used the black lead, which is actually the "shield" of the round cable. It's heavier gauge, and easier to solder another wire to it. There is a small slot in this connector that you can put a tiny screwdriver into, to release the pin and wire. Note that this lead probably will not lock in place on the I1 connector - so if you're uncomfortable with this, or don't have one of these cables lying around, I'd recommend buying the pin from Toyota. Either way, you will need to attach (solder, splice, etc.) a long (6-7') lead onto this pin.

5. Once you have the pin and wire ready, remove the plastic heater/AC duct from the upside down dash, by removing the three screws marked in photo #2. This will make it much easier to run the wire and attach it to other wires using some wire ties. Photo #3 shows the duct removed.

6. Insert the new pin into the back of the connector at pin 4. Attached is a scan of the back of Connector I1 - the pin needed is pin 4 (CLTS). Photo #4 shows my newly inserted pin - it's the black wire with a white dot. If you don't use the Toyota pin, which should lock in place in the connector, be very, very sure that the pin is inserted and has been pushed onto the pin on the sensor itself. There is really no easy way to verify this until all the wiring and dash is put back together and powered back up - so be sure you have a good connection. I tried testing it with a multimeter between contacts, but wasn't able to determine a good connection that way.

7. Run the new wire along the other wires, and out near the yellow airbag connector, securing it with wire ties. Reattach the A/C Duct.

8. Put the dashboard top back in place. Before doing any more reassembly, run the new wire however you want, through the rest of the dash. You need to end up at L7, pin 21, which is the top right connector at the Main ECU/Junction block, under which the interior fuses reside. We have not been able to identify a part number for the pin to go into the L7 connections - Your dealer may be able to, though. In my case, I have an L8 connector (used for LED headlights) that is not even connected, and there were three wires coming out of it, one large pin and two small pins. I removed the two small pins from that connector, clipped the wires, and used one to connect the new wire from the sensor to pin 21 of L7.
Note: These connectors have locking mechanisms that you need to release before inserting any pins. I have attached a drawing that illustrates this (L7 looks different from the illustrated connector, though - but the locking bar is the same idea.) I have attached photos of the L66 locking bar and pin removal method, which I used below. (The photos show the pin removed.)

9. The next step is to add a wire from pin 19 of the L47 headlight stalk connector, to pin 28 of L7. The pin for the L47 connector is 82998-24290. However, I used the second pin I scavenged earlier from L8, to connect into pin 21 of L7. I then used another unused connector on my car (for the solar ventilation switch, L66, I believe) to scavenge a pin for the L47 connector. Photo #5 shows the L66 connector I used, which is right behind the switch panel where the illumination dimmer is. I once again would recommend that you buy the pins for L7 and L47 if you're squeamish about pulling these "unused" pins from L8 and L66. (And you'll have to, if you have the solar roof - because you need L66.) The same locking bar applies to all of the L7, L8, L47 and the L66 connectors.

10. Install the new headlight stalk switch. Instructions for this can be found in hawkmoon's Fog Lights post in Technical Discussion. I have not done this yet - I am waiting for the part - but I have left the L47 connection disconnected until then. I have verified it works, though, by grounding that wire. Make sure that if you try this, you have the regular (old) headlight stalk switch turned OFF - I'm not sure how the ECU would respond to TWO grounded switch lines.

11. Reassemble the dash in reverse order of disassembly, and reconnect the battery. Note that you'll need to reprogram some things in the NAV or stereo - and if you have Nav, you'll need to wait until the map DVD loads again.
That's it! Enjoy your new auto on/off headlights!

 

What is the part number for the pins on L7 pins 21 &28?

 

Sorry, TIS unfortunately doesn't show info for those particular pins, nor the same size pins on L8.. That's the other reason I scavenged them from my L8 connector. The L8 pins definitely are the same.

If I had to hazard a guess, based upon the Toyota wiring harness repair manual mentioned elsewhere, I would say that 82998-12750 might be the right one. But no guarantees.

autopartspeople.com shows these for $11.38 each, plus shipping, which means they are probably about $15-20 from a dealer...

That's another reason I scavenged from L8.

By the way, I've been able to determine that these pins and connectors are made for Toyota by Tyco Electronics. However, they appear to be Toyota-proprietary and are not available to the general public (at least according to Tyco's web site) and after LOTS of searching, I can't find them at any electronics suppliers. I might dig into this a bit more with Tyco if I can (I have contact with one division of Tyco at work). If I find out anything, I will post it. But I don't hold out much hope.

 

82998-12750 is a very good guess. Agreed, no guarantees, but that is the right number for similar looking pins on L6.

 

I have a IV coming with SR and want everything I need before I take apart the dash. I have read that the L8 is used on some cars. Also it looks like mine has USB and SOS and some of the referenced plugs maybe used.

On another note, does anyone know how the DRL on Canadian cars works?

 

What a great thread, THANK YOU to hawkmoon77 and all that added all the extra info. I have a 2008, but the module is going to do exactly what I want. Here in California it's the law that when wipers are on, so must the headlights be!!!
This unit takes care of that little detail. I also like the auto on at dusk feature. makes driving even easier!!

 

FALSE

snopes.com: California Windshield Wipers Law

 

Thank goodness, automatic headlights are standard on Canadian version of Technology Package.

Got so used to having this on our MBs and was plesantly surprised to find our new Prius equipped with it. :cheer2:

 

If you're getting a IV, I can guarantee that even if you have L8 connected to the ECU, you can still pull the two pins (5, 21) that I discussed (and even another that I used for my fog light wiring.) The pins I removed from L8 are ONLY used for LED headlights, which are only available on the V. In fact, the repair manual indicates that L8 is ONLY used for LED headlights. Even though it is plugged in to the ECU on vehicles with a sunroof, I believe that is only because the SR requires a different ECU than the non-sunroof models, and it happens to have a receptacle for L8, where my non-sunroof ECU does not.. I don't believe there are more than three wires on ANY L8 connector - but hawkmoon can perhaps confirm that.

That leaves the one pin I got from the L66 connector, which you'll need to buy from Toyota, because you need L66, and the I1 pin at the light sensor, which you can either fabricate like I did, or again buy from Toyota. (And of course the new headlight stalk.)

And, USB does not use any of the connectors mentioned in this thread. And, sorry, what's SOS again (aside form the nautical reference)?

They require a separate relay module, not installed. It appears that the relay module gets a signal from the ECU and turns on the high beams at a reduced brightness. I do not know whether the rest of the wiring/harnesses are already present on all US models, nor if you need a different ECU. (I would have thought that the lead I needed from the light sensor would have been already there, too, but it was not.)

 

CRAP SITE! WAY OUT OF DATE... 2005???
Wth it's 2009, the NEW law went into effect last year !

SO SORRY , BUT TRUE....!!!

NEW LAWS

Effective July 1, 2008.

Use of Windshield Wipers:

• Turn on your headlights if inclement weather or low visibility (1000 feet or less) requires the use of windshield wipers.

But wait, direct from the State of Cal DMV Handbook.....


Headlamps on Motor Vehicles
24400. (a) A motor vehicle, other than a motorcycle, shall be:
(1) Equipped with at least two headlamps, with at least one on each side of the front of the vehicle, and, except as to vehicles registered prior to January 1, 1930, they shall be located directly above or in advance of the front axle of the vehicle. The headlamps and every light source in any headlamp unit shall be located at a height of not more than 54 inches nor less than 22 inches.
(2) Operated during darkness, or inclement weather, or both, with at least two lighted headlamps that comply with paragraph (1).
(b) As used in paragraph (2) of subdivision (a), “inclement weather” is a weather condition that is either of the following:
(1) A condition that prevents a driver of a motor vehicle from clearly discerning a person or another motor vehicle on the highway from a distance of 1,000 feet.
(2) A condition requiring the windshield wipers to be in continuous use due to rain, mist, snow, fog, or other precipitation or atmospheric moisture.
Please note the BOLD items above.....

Next time rather than quoting a half assed site like you did , go to the California DMV site.... they pretty much know the laws!!!

http://www.dmv.ca.gov/pubs/vctop/vc/vctoc.htm

 

Had Muhahahahaz read his own SNOPES POST, it clearly stated in the bottom of his report that Headlight Use is required if your wipers are on. Just read down in the summary of the new law and it is stated there along with the child seat commentary.

 

You are right, they even contradict themselves...
Some other laws he may have missed,
NO talking on a cell while driving, UNLESS you use a "Handsfree" device.
Soon to be updated to include NO TEXTING while driving!!!
About damn time!!!

NO TV in front of the driver..... Nobody's that good of a driver!!!!

Any other Common Sense laws we may have missed.....?????