Part number 84140-47120 I bought this to convert my 2010 Prius to have automatic headlights. It is the switch assembly that has the left hand stalk to allow automatic headlights. $65 shipped Bob
Is this a gen3 problem, why was I under the impression we all had auto headlights? I leave my lights in the 'On' position, then when I turn the vehicle off -the headlights also turn off. Maybe I've been doing it wrong all along
Gen 3 has a little mushroom-shaped sensor over on the right side of the dash under the windshield, that measures sunlight (and heat). In all Gen 3s, that sensor is used by the HVAC, so it can tell right away when you drive from shade into sun or the like, and adjust the ventilation proactively. It turns out the Gen 3 body ECU already contains a feature that can use that sensor to turn your lights on for you at dusk, and off in the daytime, if you just leave the stalk switch set on AUTO. Of course the car doesn't come with a stalk switch with an AUTO position. But it's easily interchangeable with the stalk switch that does. Depending on the year, there's a bit more work, because they left out some of the wire between the light sensor and the body ECU, and the stalk switch to the AUTO-enable pin. One thing that's nice about the feature is it also takes over the dash light dimmer. During those early twilight hours, it can turn on the headlights, but not dim your dash lights yet, until it gets a bit darker out.
Thanks ChapmanF for the explanation. Yes, all gen 3 cars have the ECU and sensor, but, the 2010 and 2011 cars need the switch (what I am selling) and some of them need a wire from the sensor to the ECU. you can search on here about retrofit auto dimming headlights to find a lengthy tutorial. I also bought some wire ends to help with the retrofit that I will throw in with the switch. Bob
got some more specific info about the model years? (I don't want to buy one & later on I have to rewire half of the car....)
This thread is about retrofitting automatic headlights. Starting about page 4, they discuss how to use factory parts to do it. This only applies to 2010 and 2011 models since 2012 and later had automatic headlights. You have to run one wire from the sensor in the top right corner of the dash (as observed from drivers seat) to the ECU, and you have to run one wire from the ECU to the wire harness in the steering wheel to attach to the new control stalk. Some cars have a wire that goes from the sensor to the harness found behind the glove box (then you have to connect from the harness to the ECU) others don't (then you go from the sensor to the ECU. So, it is two wires, but, at least one is kind of hard to get to. Automatic Headlights | Page 4 | PriusChat
