Keyless Entry Subaru

if you talk to chimpo he could probs figure out some unlocking system with it aswell :smiley:

His system only replaces the ignition barrel of a car, which my car dosent have, as its a push to start ignition system, with a wireless keyfob :sweat_smile: anyone tried it on a similar system?

I’ve hooked and xEM AC to my keyfob but as for the actuators in the doors I’m not sure

The easiest way to do this is to get a spare fob from your dealer and hack the fob. Basically disconnect the battery from the fob and when you scan, connect it, then on next scan disconnect it and toggle back and fourth.


That was my idea also, seems like a decent plan thanks! :grin:


You just made me REALLY excited! Thanks :joy::grin: how do you deal with the battery? Are you charging it whilst driving or something? Or are you just using the car battery to Power it? Also, if using the car battery, what kind of leakage current do you have? I can imagine the voltage regulator consumes a bit…

The fob is powered by the car, but powered down most of the time… The xAC (edit: using the V1 controller, not the new one) takes up a decent amount of current (13-26mA IIRC). The controller I made goes to sleep and draws 8mA.

If you don’t power the the fob off, the car thinks you left the fob in the car and will not lock.

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Close enough
11mA idle 48mA when reading.
This is quoted, I have never actually measured it

I’m still working on getting my wired to my car battery so I can permanently install it and make a full project outline :smile: :sweat_smile:
I wonder if I used an extra car battery how long that would last?

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It’s hard to measure because it’s constantly changing due to the pulsing antenna. I measured it with a very fast 7 digit bench meter, but it being fast doesn’t help my eyeballs read it lol. I don’t have a current probe for my scope. It seemed to swing between the numbers I quoted, while at idle. I did not measure it while actually reading which I assume would be higher, but I was only interested in idle draw.

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Roughly: Time = capacity (Ah) / current draw.

I typical PbA automotive battery has a capacity of say 70Ah… Give the average draw of the reader and the controller to be 30mA, you get 70/0.030 = 2333 hours, or 97 days. Now the battery will cease to be able to crank your engine far before that.

Do you go weeks without driving your car that you are worried about this? If you drive more than once every week or 2 it will be fine.

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No I drive it nearly every day, I meant more as if I just had an extra battery in say my trunk how long it would last. Which judging by the ways people use them for massive speaker setups I’m sure there’s a way to have it connect to the alternator as well?

Voltage Sensitive Relay

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There is also the “old school” traditional battery isolator.


Eyyy good news, the key works superb on the 3.3V supply from the arduino (altho teoretically it uses a 3v battery) so protyping is super easy, also the buttons to close/open the car work nicely even when the keyfob is in the car, so now i just have to hook up some transistors to replace the buttons, and a relay for the 3.3v power supply, then i can test it with a button or something else i have lying around (before i buy a rfid reader :P)

also the battery terminals in the key are laaaarge, so no problem soldering, the button terminals however… not sure how to go about doing them… also other soldering points very close to them, so i cant really over dimension it…

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I used a transistor to control power to the fob.

Well, killed the keyfob with heat -.-

F in the chat

got wires onto the battery terminals and that worked, got wires over one of the buttons, that worked, tried to get wires onto the second button, PCB got darker, and on the other side of it was an IC -.-