Automatic Headlights

I finally got mine done after a wild goose chase on L7 connector pins that flunked. Many thanks to those who paved the road. I did the Canadian stalk.

Two issues I ran into:

a) The cable connecting the Nav system GPS antenna on the upper dash has a disconnect, BUT the cable running into the lower dash has a tie-down on a metal bracket attached to the upper dash. So, when you pull the upper dash off, you also pull the coax cable out of the connector attached to the upper dash bracket! Unfortunately, the connector on the bracket has a release clip only accessible from behind the bracket. This looks like a manufacturing design defect. I managed to reconnect the coax cable to the connector when I put the upper dash back on. GPS appears to work fine now.

b) This may have been mentioned before in this epic thread, but if you reverse the wires to pins 21 and 28 on L7, the headlights will flash off and on whether they're on regular or automatic. They flash at a different rate depending on whether the sensor is covered or exposed to light.

 

I'll answer this myself - the pins in the grey unused connector fit L47, but not L7. So it goes.

 

Tried the auto headlight feature today going thru some tunnels on I-90. The dashboard light adjustment is very quick to transition from bright to normal coming out of a tunnel, but the headlight delay is 13 seconds, way too long.

Can the headlight on/off delay be adjusted? Thru Techstream?

 

Following this excellent thread and discovered and was planning to do the mod. Yesterday discovered that on brand new 2012 III going through tunnel that dash dimmed and came back. Does that mean sensor is already hooked up?
Do I just need switched ground on 28 ECU ?

 

Probably, try it with a rigged wire to ground then cover the sensor with a dark cloth. Wait at least 20 seconds after covering the sensor.

 

I am getting ready to do this mod next. Assuming i have the L7 pin, I plan to get the Canadian stalk, part number 84140-07141 and do the mod. I do have a problem and I hope someone can help me with the answer.

My 2012 has DLR and therefore my light stalk has a DLR setting. The Canadian stalk mentioned in this thread has fog and auto setting but no DLR. is there a light stalk that has fog, auto, and DLR? My local dealer is no help! What are my options if I cannot find the stalk with all three settings? Thanks in advance.

 

I also have DRL setting and was wondering if it can be used as auto. I can not find on TIS a diagram which would correspond to this model with DRL and no auto. If anyone traced where DRL from the stalk goes pls share the info.

 

You can get the stalk for the US version Prius Five as it has DRL, auto and fog.

 

Looks like the L7 pins hack is not going to work on 2012 with DRL. both pins are already wired in and 28 is switched ground via stalk in DRL position. I could find anything on TIS how it is wired. Anybody has any suggestions ?

 

sailnw,
I plan on this mod and have already ordered the 2012 prius IV headlight stalk as auto headlights are standard but not HID or Fog.
I have been looking over TIS. looks like our cars (2012 ) are already wired. Wiring diragrams confirm pin 4 of light sensor goes to pin 21 of l7 (signal to body ECU).
It also shows L47 pin 19 to l7 pin 28 is there. the wire from stalk to body ecu for auto lights(for all models).
According to TIS the prius III is using pin 19 for the DRL, but the new stalk uses pin 19 for the auto mode.
Looking at the stalk wiring diagrams it looks like all models have 4 positions for the lights.
Off | or DRL off
*DRL on | or Auto *
taillights
head lights on

TIS shows the same wiring for all models, but not ECU logic, ECU could be programmed to send constant voltage through pin 21 to pin 19 instead of photocell switched.

I can not find Logic of the body ECU. the DRL are using the auto slot,(pin l47 19 to l7 28) which should be switched by the ecu according to the photocell, but obviously is not swithed with the photocell or the DRL would turn off in light. Our cars also have DRL on : off via our nav screen as well as the stalk. my nav DRL on : off is useless right now, it is controlled by the stalk, it does not care if it is on or off via the nav screen.

This is important because there might be a chance we have to replace the body ecu with one with the correct logic. one that controls the DRL through the nav unit, and sends switched photocell voltage from pin 21 to l47 28. I could poke around and find a photocell switched 12v for the Auto, but I am not sure about the DRL...we could always put another fog lamp style switch in for the DRLs if the ECU is too costly.

If anyone has a tech stream handy could they see if you can reset the Main Body ECU and configure it to another setup? or if it is plug and play only.
Thanks.
I will let you know what happens.

 

Ok, I have some bad news on the 2012!
I would like to get the CEO of American Division of Toyota on the line!
The Prius 3 DOES have a different body control module (multiplex ecu) than the prius 4 and 5 (which offer auto on lights). I have looked at the wiring diagrams and both stalks, everything is identical. Prius 3 has a photocell which controls the nav and cluster dimming automatically (through the can bus, not 12v signals) this leaves no back way of making the stalk work in auto, the only solution is the after market 4225 type module, or invest the 800 bucks on the stalk and new BCM.
I am very dissapointed in Toyota. This means they actually spent more money to keep you from having auto lights, it would have been cheaper to keep one style stalk and bcm.

 

The auto/on/off headlight problem is truly Kafkaesque. A great safety feature on any car but especially on a car with digital dash which eliminates the main cue to turn on one's lights, not being able to see the dashboard. But on a $30K super tech car like the Prius, no available on most models. Boooooooogus.

I talked to my dealer and dealer on Canada where DRL and the auto headlights are standard. End of the day, from Toyota it requires a $1,000 computer update plus installation plus replacing stalk on the wheel, more parts and labor.

As you note, the light sensor and wiring are already there are likely one of the home mechanics here could figure it out.

 

I have finished this mod on my 2010 Prius with solar and Nav. I did find that my car had the wire from the sensor to the connector above the glove box after I removed the dash. I did order the stalk with the auto headlights and fog lights. The full auto headlights now work as they should, thanks everyone for all your input. The fog lights work as they should and when I Hook up my car to my TSI software it shows that the fog lights are turning on and off as it should. I decided not to use the internal fog light relay and wired a separate relay so that I could leave the fog lights on all the time for DRL without having to leave on the tail lights.

I am also adding heated seats to my car.

 

Thank you for the awesome DIY.

Too bad it will cost too much and not worth the extra work just to keep the solution OEM for my 2012 III.

 

Seems like an awful lot of trouble to go to instead of just turning the lights yourself when it's dark or it's raining? Just sayin'...

 

How did you wire the fogs to be on all the time? I'd like to do this on my Prius? Would it be too much trouble to detail which wires/wiring you had to tap/configure and how to wire up the relay?

 

I did the same with my foglights. I tapped into a fuse under the driver's side dash, I believe it was one of the fuses for the seat heater (5A), which becomes hot when in Ready Mode. I believe there are options available in the main engine compartment fuse box as well.

 

I guess it might be different with the five and the fog lights being already installed by the factory

 

Sorry, I didn't notice you have a V. Yeah, my foglights are add-ons with a separate relay. Easy to tap the relay into any wire getting power.

 

I installed the DEI 545T in 2009 when I got the Gen III Prius. The photocell is located in the center of the dash close to the windshield. Whenever the wipers are on, they create enough shadow to turn the headlights on. So it works out, if the wipers are running the headlights are on.

I also wired the DEI 545T power to a relay on my Viper remote start. If I remote start the car it turns the auto headlights off. So if I remote start the car the head lights do not come on. When I get in the car they turn on. It also has a pittstop mode that lets me lock the door and keep the car running if I am making a short stop. It is set to turn off the head lights when that mode is activated.