Re: Cig lighter kill switch

[Luis Marques <marques@xxxxxxxxxxxx>]

To add to Norman Boehl's great schematics of the cig. lighter kill
switches, here is the diagram of the fuel pump kill switch, as I
implementred it.  The normally open relay interrupts the current to the
fuel pump.  It is closed by pressing the two momentary-on switches
simultaneously with the ignition on.

Once the relay contacts close, power from the fuel pump fuse is routed
back to the relay coil so it is "self-energizing" and stays closed
regardless of the switches.  This keeps the relay energized after you
let go off the switches.  Once the car is turned off, power to the fuel
pump fuse is cut off and the relay opens (and will stay open until the
sequence is repeated).  A hidden on-off switch could be wired in
parallel with the switches to allow valets to park the car (but if the
thieve finds it, you're SOL).

This will also work with only one switch, or the cigarette lighter could
be used as one of the switches.  Or you can have both a starter kill
switch _and_ a fuel pump disabler.  HTH, have fun, and don't let the
vandals take your pride and joy.

NORMAL WIRING
=============

Fuel                                                        Fuel
Pump------------------------------------------------------> Pump
Fuse     ^                                                  Relay
         |
         +-- cut here


MODIFIED WIRING
===============

Fuel (12V only with ignition on)                           Fuel 
Pump---------o                               o-----------> Pump
Fuse         |                               |             Relay
             |       RELAY (N.O.)            |
             |      +----------+             |
             |      |    /     |             |
             |      |   /|     |             |
 +-----------+---------o |  o----------------+
 |                  |    |     |             |
 |     /      /     |    |     |             |
 |    /      /      |  +-+--+  |             |
 +---o   o--o   o-+----|    |-------+        |
    Momentary-on  | |  +----+  |    |        |
  "kill" switches | +----------+    |        |
                  |                 |        |
                  |                 V        |
                  |               Ground     |
                  +--------------------------+

------------------------------