Plug N Play Auto Headlights for the Prius C

Thanks

 

545T is not plug and play. There's no male and female plugs that plugs directly into the factory harness. You still need to wire it up just like any aftermarket modules.

Hydreon Rain Tracker has auto wipers and auto headlights. It works pretty well. There are several youtube videos where it activates the wiper as soon as rain drops on to the sensor area of the windshield. Mine works well even after 4 years.

 

i finally decided to purchase this kit and it's arrived. i took the parts out and have lots of questions. since y'all said it was so easy, i wanted to give it a shot and i have lots of questions. i am a completely newb at auto stuff so please bear with me

i took pictures to see if i'm understanding the directions right.. quoting the OP - please tell me if i do have this right someone

"Unit has to be prepped to be specific for the C. I started by removing one of the 2 relays. I kept the one with large green and purple wires." -
when you say removing the relays, are you simply cutting the red wire? do you need to cap the end of both red wires after cutting with a wire nut? see picture - is this right?



"Second, I opened the module and cut the red wire. I did not want it to run my daytime running lights. I use the stalk for this feature."
- i assume there's a red wire you just cut and cap? showing picture to make sure this is the module


"Next, I removed the wires I did not need on the largest plug. I kept only the Red, Black, and Yellow.If you want automatic wipers, keep the green."
how do you remove the wires? do you cut each one and cap it?


"The light sensor needs to be stuck on the dash and run the wire down to behind the panel on left lower. This is where you will mount everything.
You will need to remove that panel and the lower one from the steering colum, 3 screws and a few push in connections along the edge. One screw is under the panel, below the steering wheel. The other two are on left and right side, behind wheel. You will need to rotate the wheel to get to them."
Not sure I understand this entirely... where did you guys mount the relay & the module? did you use velcro or something? and how did you run the wire down?

"This is how I wired mine: I connected red and yellow together and hooked them behind the cigarette lighter, after removing the glove box. You will have 12 volts here with ignition on. You may want to tap a wire under the steering wheel."
how do you connect red and yellow together & tap it to the one wire behind cigarette lighter? can you use a wire tap? or do you need to use two taps, one for each wire on the 12v source? what wire is the 12v source?

"I grounded the black wire, from module harness and the violet wire, from relay, to a bolt head behind the panel, in the dash. The green wire from the relay has to be hooked to the headlight wire on the big connector under the steering wheel, on the left side. This unit throws a ground to this connection and turns on the headlights. Connector is L-47 pin 11. This is a light blue wire on the bottom row on the left edge. I would call it number one wire, on bottom, from the left. There are no wires on the top row of this connector. Will post a picture of this connector."
there's two green wires in the relay - which one did you use?



Last question - are you guys using the switch at all? what does that do? just disable the function of the auto-on light?

 

Essentially, yes. I did use the switch, but I cut the switch off the small wire harness and replaced it with a switch I found more aesthetically pleasing. I mounted this switch in the knock out next to the dashboard dimmer switch to the left of the steering wheel. This will allow you to over ride the relay and will allow you sit in the car at night, ignition on, and have the headlights off. Otherwise there is no way to power off the headlights at night when the car is on. For example, you are waiting to pick up your kids at night and want to listen to the radio without having the headlights on. Here is the switch I used, but it did require some judicious filing and dremel tool work to make it fit and I had to epoxy it in place.​

​

Hope this helps. Bottom line, is call call customer support if you have any uncertainty. It really appears they have changed the wiring on the relay.​

 

is there a way to get this module to work only when in the DRL stalk position? that way you would have drl and then auto lights but also have the ability to turn everything off by the stalk.

 

I would imagine it is possible. You would need to find a way to have the "off" position of the stalk to tie into the override switch attached to the control module. I am not sure how to do that though, and it may involve adding another relay. I leave my stalk in the DLR position pretty much all the time. In the DLR position, the headlights will still turn on automatically at night. But to turn off the headlights at night, I have to hit the switch I added on the dash.

 

thanks for the info - wondering - the kit you got - is it the same as mine? i really don't know anything about wiring and only purchased it because the posters here said "anyone can do it" so if you know the answers to my questions -that'd be awesome

 

I have the same DEI model 545T. But the wires coming out of your relays appear to be organized differently. Do the instructions that came in the box match the instructions I posted? My guess is they do not, and you will need to look at the instructions you have to determine the headlight relay input and output wires. If you cannot determine those wires from your instructions, call DEI customer support. As far as, "Anyone can do it.", I would preface that with, "anyone comfortable using a multimeter and soldering and/or splicing wires can do it." If you are not comfortable doing this, just take the kit and your car to an installer.

 

did you post the actual instructions? not sure i saw a link for those... i've never soldered/used a multimeter, but i could learn. can you use wiretaps instead of soldering?

also - wondering if there's a trick to remove the wires from the relay? is it just cutting them all and capping them? or can you actually pull it out somehow?

 

Do you guys have any tips on which wire to tap into for a constant 12v source? I like the idea of the headlights staying on for a short while after the car's off.

 

I installed the module today. It took me most of the day, since this is my first time doing anything with auto electronics, and my first time mucking around behind the panels of my new car. Here's what you can do to avoid my same mistakes:

• The easiest source of constant 12v+ power I could find was behind the head unit. Specifically, the black wire coming out of the 10-pin plug (pin 4 on G37/G76) is constant 12v+ from the battery.
• Rather than getting ACC current from the cigarette lighter (I still can't figure out the trick to getting the glove box out; I put my whole weight into it, and the tabs still wouldn't go in far enough to avoid the stoppers), you can get it from the G14 Windshield Wiper Switch Assembly by using the black wire. TIS says it should be in pin 2, but mine was swapped with yellow in pin 3. YMMV, so give it a check with your multimeter.
• The lower instrument panel finish panel LH (left kick panel) can totally be removed independent of everything else, in spite of what the TIS disassembly instructions say.
• Don't try to get constant 12v+ power from the horn 12v+ input, unless you want your horn going off when your headlights are on! Also, try to remember that grounding a power source completes a circuit. I know, I know, but it was too tempting not to try.
• Posi-taps rock. Less penetration than a standard T-tap or Scotchlock, less skill and knowledge required than soldering. They're expensive and hard to find (NAPA or Amazon are your best bets), but they make it super simple to connect things. Additionally, they make really nice testing points.
• TIS is totally worth it. It takes a little bit to get familiar with the interface, and digging through it to find a generic feature (e.g. a constant 12v power source) versus a specific one (e.g. getting off that kick panel, what each wire on a harness does, fuse power source identification) kind of sucks, but once you get used to it, it's fantastic. AlldataDIY is significantly cheaper, so I may give that a shot next time I'm inside the car, but the $15 for two days of access saved me so much trouble and guesswork.

I haven't had a chance to take the car out during the day, but testing with my garage's lack of light turns the headlights on, and my phone's flashlight for ~20 seconds turns them back off, so it seems to be working. The lights don't stay on after turning off the car power, which is kind of a bummer, so I may investigate that some more. Does the rheostat control that? I also didn't hook up the wiper input to the wiper controls, so, one more thing to do next time. The instructions for the unit claim that the lights stay on 30 seconds after the wipers do, so that may get rid of the potential for the lights flashing in intermittent mode. Maybe that's what the rheostat controls?

Given the issues I had getting this simple module connected, I'm glad I didn't jump right into the rain tracker. I may upgrade in the future, now that I *kind of* know what I'm doing. I'm just glad that I now have feature parity with my old car ('07 Corolla).

 

hey RandomString - did your module and wires look like mine? i'm still at a loss in terms of knowing what to cut and how to do this - but i do want to give it a try.... posted some images and questions earlier - would be curious how you did it. thanks is cutting wire still required? and opening the module?

 

here's the wiring diagram that i received :

 

I think your module is the same as what was originally posted in this thread, or at least close enough that all the same instructions apply. The only wires you need to cut are the red wire between the two relays, the wire connecting the unused relay to the connector that goes to the module, and the red wire inside the module itself.

Before you go connecting this thing to your car, you might want to try to get a better understanding of what you're doing first. A relay is kind of like a light switch controlling an outlet in your house. When power flows through the switch, the outlet turns on. Similarly, with the relays in this system, when power flows between the thinner wires, power is allowed to flow through the thicker ones. Since one of the thin wires goes to the module, the other needs to go to ground (the car body) for power to flow through it. This is what lets the module "flip the switch" for the headlights. The other set of connections on the relay, the thick wires, connect the headlight control wire to ground when the "switch" is flipped to let power flow. When this happens, the car thinks the stalk was set to turn the headlights on, and does so.

That explains the relay. As for the rest of the wires, you've got constant power, switched power, and ground. The original instructions treat the first two the same, since the headlights only need to be on when the car is on. As mentioned above, the cigarette lighter provides power only when the car is on. Using this, power can enter the unit, and is used to power the module, control the relay, etc. But if the power can't go through the unit and complete a circuit, it won't go anywhere. That's why you need to ground it to the car frame.

So, in summation, power comes into the module through the constant power line (with the switched power line enabling and disabling the module), and if there's not enough light coming into the photocell, flows the the control wires of the relay. When that happens, the relay is switched on, and power from the car flows through the headlight stalk wire, through the relay, into ground, and turns on the headlights. When it's bright enough again, the relay flips back off, power doesn't flow to ground in the headlight stalk wire, and the headlights turn off.

 

Thanks for the info RandomString. That's super helpful - really appreciate the writeup.

I think I'm close to trying this - one more dumb question for you - so each of the wires has a plug into the relay/harness, and the other end is another plug (I'm assuming that's supposed to go into the car). I'm assuming you cut off that end of the plug in order for you to direct wire it to the car - is that right?

Thanks again

 

Hey all,

Finally getting around to this. The OP mentioned how he connected the green wire but he didn't mention how he connected the violet wire. Where are you supposed to connect that one? The diagram says that both green and violet are for the headlight relay... Violet is the input and green is the output. Thanks!

 

The violet wire is polarity selector. Toyota light switch at stalk is negative trigger so you would ground the violet wire.

 

First of all: "Hello" I just signed up even though I've been reading here for a while.

I bought the module and played with it today, but couldn't get it working the way it should...

I wired everything the way the O/P posted and the following happened:

- When the stalk is in the DRL position, the light sensor simply turned on and off the DRLs (which is almost the same in the Four, but the taillights didn't come on)
- When the stalk is in the parking light position, the module turned the headlights on and off, but the tail lights where always on!? Also, I didn't have any DRLs in this setup

Can anyone help me which this? The module I received from Amazon was an open box item and someone previously cut the red wire inside, so it was definitely not new.

 

See next post

 

Here's a little more info: I found an older thread by sfv41901 explaining the behavior on a newer Prius. The Prius C4 with LED lights has the exact same oddness.

When using just the 1 relay on the headlight circuit with the light stalk on the DRL position, only the headlights are energized, not both headlights & parking lights. If the stalk is left in the off position then both the headlights & parking lights are energized. The down side of using just 1 relay is that u will never be able to use the DRLs.

So basically the above instructions work, as long as you have the stalk in the "off"position. You will loose your LED DRL functionality though. If the stalk is in the DRL position, you never have working tail lights...

I will dig deeper to find out if this problem can be fixed with a second relay.