PriusHybrid.com
Prius Card Access System Technical Description
A card access system controls access by enrolling cards with individual permissions. In this application, only one reader is used, so all cards are enrolled with full permissions. You could, however, enroll a card that would only be valid for one day, one week, etc.; or if a card is lost, you can just void it. This description would turn into a book if I described all the possibilities available with this system. All programming is done via a specially wired serial connection to a pc or notebook. You can go to the kerisys.com website and download the "Doors" program if you want more details about programming. Basically, programming in this application involves enrolling cards then setting up inputs and linking them to the desired outputs. Kerisys.com has a users guide for the Doors software that describes the programming details. Parts for this project are available here.
This system is comprised of three integrated elements:
1. Door lock/unlock
2. Hybrid system start/run
A. Board connections
B. External relay connections
3. Power
The door lock/unlock is relatively simple. Presenting a valid card at the reader causes a 1 second ground pulse to the KUL terminal of the Power Window Master SW (via Lock Output), simulating unlocking the driver's door with a key. This, of course, also turns the alarm system off. The locking is done by simply closing the driver's door. The driver's door courtesy switch is tapped into and run to Input 8. This sends a 1 second ground pulse to the KL terminal of the Power Window Master SW (via Output 2), simulating locking the driver's door with a key. This happens every time the driver's door is closed, whether entering or exiting. Fortunately, Prius is smart enough to automatically turn off the alarm system once a valid key is inserted in the ignition switch and turned ON.
The Prius Hybrid system is started by fastening the driver's seatbelt with
the "transmission" in Park. One other thing that happens when a valid card
is presented (in addition to unlocking the driver's door) is a 1 second pulse to
Input 7. This starts a 254-second timed pulse to Output 1 which supplies
+12 vdc to COM of Output 3. So, a window is set that allows starting of
the Hybrid system. In other words, after presenting your card, you have
about 4 minutes to get in and fasten your seatbelt. If you wait longer,
the ignition will turn ON, but not start--kind of like using an ignition key
that turns but is electronically invalid. This time is programmable from 1
to 255 seconds and it could be extended by adding an external timer (such as the
Altronix 6062 timer).
When the driver's seatbelt is fastened within the 254-second window, Input 4 and
Input 6 are activated via body ground from the seatbelt switch. A diode is
used since we are getting ground through the Prius' electronics. The diode
simply ensures that the board can get the ground impulse, but can't send any
potentially damaging impulse back to the Prius' systems. Since we removed
the Prius' wire from it's connector (connector
unlock tools), we need to provide the ground signal for
the T6 Tension Reducer Solenoid that it was connected to, when the seatbelt is
connected. This is accomplished with the NO2 connection of Relay 1 (R1).
Now, back to Input 4 and Input 6. Input 6 follows Output 4. That
means whenever there is ground at Input 6 (seatbelt connected), Output 4 is
activated; remove ground from Input 6 and Output 4 is deactivated. This
input/output simulates turning the ignition key to the ON position. It
gets a little complicated here because I don't want to be driving along,
accidentally hit the seatbelt release button and have the car shut down.
So, we set up Relay 4 as a latching relay that, once activated, can be
deactivated only when the "transmission" is in Park. Output 4 activates
Relay 4, then the Park SW keeps it activated until both it's back in Park and
the seatbelt is released--either one by itself will not shut the Prius down.
The Park SW is a SPDT D44 Cherry (miniature) switch with an extended lever arm.
I attached it to the Prius Park/Neutral switch, then adjusted the lever arm (I
removed one of the screws of the Prius Park/Neutral switch and replaced it with
a longer one). On Relay 4, the first pole (COM1 and NO1) handles the
latching part and the second pole (COM2 and NO2) activates Relay 1 (R1) and
Relay2 (R2). Relays 1 and 2 interface with the ignition switch to simulate
the ON condition. Now for Input 4. Input 4 sends a 1 second ground
pulse to Relay 3 (R3) via Output 3. Remember this can only happen in the
254-second window set up by Input 7 / Output 1. Relay 3 interfaces with
the ignition switch to simulate a start condition. The Prius needs to see
a valid chip in the head of a key to complete the start process, so we strap the
head of a valid key to the ignition switch immediately on the back side of the
Transponder Key Coil (about at a 2:00
position). At this point we're in our securely locked and running
Prius but the steering wheel won't turn. So, remove the ignition switch
and fashion a pin to hold the release arm up, so the steering wheel will be
unlocked at all times. I used round spring steel shaped to a tiny "U" to
fit in the channel (modified ignition switch).
The system is powered by a 25 Amp Hour battery. At rest, the board (including power for the reader, all relays are off) pulls 0.25 amps. So, on a fully charged battery, I have almost 7 days of reserve (see Altronix Battery Capacity Calculator). You can use that calculator to see what size battery would fit your driving style. The battery is kept charged by a solar panel that sits on the back package shelf, between the ventilator intakes; and the Prius charging system. Charging from the Prius system is through the "CIG" fuse, so it is only connected when the Prius is ON. A 6 amp diode is used so that power can't go to the Prius. If the battery is too low, you have to resort to using your key.