Automatic Headlights

Well, it took me a little longer to get out and take the pics than I planned, but as promised, here they are. Just to recap, this is where I found the lead from the light sensor stopped on my 2010 Prius 3. To find this connector you need to remove a few dash panels, but there are no screws and it can be done in under 5 minutes. If your car is like mine you can do Jayvee's factory autoheadlight mod without totally ripping apart your dash.

You'll find pictures to help guide you along below. First, start by removing the top of the center console with the cup holder in it. I started by the cupholder and just pulled up. Once that part came off just work your way around and keep pullng mostly up and slightly towards the back of the car. Be careful because it's got a thin arm that comes off with it that goes up and to the right of the radio. There are a couple of cables plugged into that trim piece, but for our purposes you don't need to disconnect them. Just stretch them out a bit and move the trim piece off to the side as shown in the picture.

Next pull off the passenger's side window defogger vent. This comes out by pulling mostly toward the back of the car and slightly up. After that, pull out the passenger side HVAC vent. This comes out by pulling toward the back of the car. It helps if you open the passenger door to get a grip on the right side of it and the upper glove box so you can slide your fingernails behind the left side of it.

Finally, pull out the upper glove box. This slides out toward the back of the car about an inch to release the fastners, then you'll need to pull the bottom out first and rotate it to get the hingers out from under the top of the dash. It helps if the box is open while you're trying to rotate it out.

Now, if you look in the space behind the glove box you'll be able to find three connectors. A yellow connector for the passenger airbag (don't touch that one) and above that a black and white connector (they're under the dash a bit in the circled area in the photo below) There's also a close up of the two connecters.

Unplug the black connector (there's a latch you need to push in, then it slides out very easily. If it's not coming out easily you probably don't have the latch in far enough).

Finally, if you look inside the black connector that's still attached to the dash board (not cable you just unplugged) you'll see several pins. You're looking to see if there is a pin in the upper left position (circled on the close up below). If this pin exists (and your car is like mine) then this leads directly to the light sensor and you can do this mod without taking apart the whole dash. If this pin doesn't exist (like in Jayvee's car) then you'll need to do more disassembly to get to the actual light sensor.

If you do have the pin and your car is like mine, you'll note that there is no wire that connects to this pin on the cable that pulgs into the connector. You'll need to get a pin and wire into there and run that to the L7 connector on the ECU on the driver's side. I'm sure you can purchase this pin from toyota, but like Jayvee suggested in his post I salvaged some pins from the unused L8 connector (near the L7 connector and not plugged into anything). He (and I) used the two smaller pins from that connector for the connections we needed to make in L7 and I used the larger pin from that connector for the connection under the dash.

You're on your own for getting a wire from there to L7 on the driver's side, since I already had my dash completely taken apart I ran my wire next to the existing wire loom... but that's not accessible unless you completely disassemble your dash. I took a quick look when I was taking these pictures and it looks like you may be able to run it under the radio.

Good luck and I hope this helps someone,
Brett

 

OK, so this is really cool. I just discovered that there's a great feature with the factory auto headlights. When it starts to get close to dusk and the car decides it's time to turn on the headlights it will turn them on, but the instrument panel stays lit at full brightness so you can still read it since it's still reasonably bright out. Later, after it's darkened more the instrument panel will dim to avoid hurting your night vision.

The same thing happens in reverse in the morning. When it's dark out and you start the car the headlights come on and the instrument panel is dim. After it starts to get brighter out the instrument panel will come up to full brightness and the headlights stay on. Later, after it brightens more the headlights will shut off.

 

Yep......its pretty cool. I was driving a 2011 Camery a few weeks ago & it did the same thing

 

Slightly confusing though, since my expectation was the change in dash brightness coincided with activating/deactivating the headlights. that's the way it worked in my last car.

 

Yes, I agree. The first time it happened was the evening after I did the mod and I thought something went wrong when the instrument panel lights didn't dim, then they dimmed a short time later when I went under a big bridge. When it did the same thing in the morning I realized it was a feature... And realized how cool it was

Brett

 

Nice write-up. Wish my sensor wire had been there too!

Jayvee

 

I just completed my "upgrade" to the automatic headlights with the factory stalk and using the factory light sensor. THANK YOU to everyone who did the legwork for the rest of us!!!!

It was MUCH easier to take the dashboard apart than I expected. Everything went back together well with no issues (no creaking or rattles!).

I have a V with ATP; there was a connector (for the solar air recirculation switch?) that was unused, so I cannibalized it for the connectors.

Everything works perfectly!!!! THANKS AGAIN!!!!!!!:rockon: You folks ROCK!!!

 

The solar air connector pins fit the L7 connector on the Main ECU?

 

Ooops, you're right. They don't fit the ECU, but they do fit everywhere else. I got a little befuddled with the ECU connector - I chickened out on disassembling it, so I followed someone else's recommendation and just "jammed" the wires in it. I think (and hope) it's engineered to not let any strays into its neighboring slots. So far, so good. (is there a "fingers crossed" emoticon?)

 

Having done this mod and disassembled the connector enough to get some pins into it I'm pretty confident that you won't have any problems with anything coming in contact with a neighboring slot... I think the only risk is that a wire might work it's way out over time, but that shouldn't be too much of a problem.

 

I asked around and I'm being told that this happens with or without the auto headlight mod. I had to ask because I don't remember if mine did that before I did the auto headlights on my car. BTW, auto headlight steering wheel stalk FTW!!! Much more effort but I'm glad I did it. Really looks OEM. I had the dealer fooled a few times when I brought it in for oil changes.

 

I agree... I first did the auto headlight mod at the end of January and ordered the OEM stalk shortly after that... and it finally arrived yesterday. I ordered it at the same time as the auto dimming homelink mirror and I know that at least one part was out of stock and took a while to come in, but I don't know which one it was. I just got finished installing the stalk and the mirror and I'm very happy with both of them. Definitely worth the time and effort.

Of course, I also set myself up for my next project with this... I went back and forth a bit, but wound up ordering the stalk with the auto headlights and the fog light switch... so now I've gotta actually get the OEM style fog lights and install them.

Brett

 

I'm still holding out hope someone can come up with the proper part number of the repair terminals needed to the main body ECU L7 interface for getting the factory auto headlight mod working. I did some searching and found this document:
http://www.xpresskit.com/DocumentDownload.aspx?documentid=6807&productid=461&firmwareid=1950

Based on the information and diagrams in there, it looks like the Prius 2010 main body ECU L7 interface is identical to that of the F9 on the Lexus hs250h. And very likely the same interface as these vehicles (interface name in parenthesis):
2010 Lexus GX460 (G47), Lexus RX350 & Lexus RX450h (F13),
2010 Toyota 4Runner (F9), 2011 Toyota Sienna (D13)

Does anyone have access to TIS and based on the above information find a working part number? It doesn't matter if it's a Lexus part. As long as I can order them from somewhere and they fit, I'm good.

I have a Prius 5 ATP with LED lights, so I can't harvest anything from the L8.

 

Ok, just got done reading through the 20 pages I cannot wait to do this mod.

Did anyone confirm this will work on a 2011 Prius II?

 

I had the dealer install the Canadian Switch for me today (Auto headlights and foglights). In the process, the skid light, brake light and ABS lights came on. The dealer says that they have to order an angle sensor. How did you clear the skid light?

 

So....I have been reading this thread backwards and forwards and my eyes are starting to cross. My question is simple. I have the pin available behind the glove box at the connector you describe on my 2011 Model II. I don't really care if the Auto-On/Off is switchable. (I set my 2007 Matrix to On and left it there for the four years I owned it). I run a lead from that to the L7 connector, PIN 21? Is that all there is to do to get Auto On always or did I miss a step?

Thanks!

/randy

 

You'll need to make two connections on the L7 connector. The one to pin 21 that you described above and another to L7 pin 28.

Connecting pin 28 to ground is what tells the ECU to enable auto headlight mode. Normally that would be connected through the new stalk or another switch so you can turn the auto headlights on and off, however, you could just permenantly ground it to leave them on all the time. (I actually grounded it to a nut a few inches above the L7 connector for a few weeks while I was waiting for my new stalk to arrive and had no problems).

There are two caveats that I see to leaving this permanently connected like that. First, the car was designed so that the headlight switch would only be in one position at a time... Parking Lights on OR Headlights on OR Auto Headlights on. If you ground this connection permanently and you (or someone else driving your car) operates the normal headlight switch then the ECU will be getting the Parking Lights or Headlights On signal in addition to the Auto Headlights on signal. No one really knows what would happen in this case since the switch is designed so this can't happen... most likely nothing, however, it is concievable that it could short something internally in the ECU and cause damage. You may want to consider disabling your existing headlight switch somehow to avoid this possibility.

The second issue is that it seems like whenever I take any car for service one of the first things the mechanics do is turn off the headlights. Since your headlights would be permenantly set to auto they wouldn't be able to do this... this would certainly cause some confusion for them and worst case even some extra diagnostic time as they try to figure out what's going on with the headlights. It could also cause problems with some of their diagnostic tests if the tests require the lights to be off. Of course, you could always manually disconnect this before you brought the car in for service, but that would be a bit of a pain too.

 

Maybe I will pick up a button from Toyota and just make it switch to ground (or not) on PIN 28 of L7. My understanding is that everything in this mod switches or lifts ground so there probably would be no damage to the ECU, but I really don't want to find out. Also, I am not really interested or motivated in finding and replacing the OEM stalk at this time. Thanks for the quick reply.

/randy

 

Yeah, that would work to make it a bit easier to disable it before you bring the car in for service, but it still wouldn't help with someone turning on the headlights from the existing stalk while the auto lights were also on unless you also disabled the existing switch. If you are going to go that route I might be inclined to spend a couple of dollars for a switch at radio shack and just hide it under the dashboard rather than spending a lot for a toyota switch.

I agree on both counts.

Doing the stalk really wasn't that bad. I ordered it from parts.com and it was a bit under $100 (a bit over $100 with their outrageous shipping charge, however, still cheaper than I could find anywhere else). Actually installing it wasn't too bad either... around 30 minutes, as I recall, including the time spent disconnecting and reconnecting the battery. You have to remove the steering wheel to do it, but it doesn't require any special tools.

 

I know! If the auto lights are ON and you move the switch to parking lights or driving lights, nothing happens. You cannot override the Auto ON. If Auto OFF and you change the stalk to parking lights, the parking lights come on, but the indicator on the dashboard DOES NOT light up. if you move to driving lights, they also come on, but the indicator on the dashboard still DOES NOT come on. So you can override Auto OFF, but you can't see it on the dashboard.

Same as yourself i first grounded L28 to the bolt a few inches above it. I also realised this mechanic/testing scenario would occur, or some other scenario where it was dark but i did not want my lights on. I fitted a small switch into one of the blanks in the dash and fitted it next to the headlight adjustment switch. in the On position the Auto headlights are on, the Off position Auto headlights are off. Works perfectly.