18 © 1999 Directed Electronics, Inc. Vista, CA
The vehicle must have a vacuum actuator in each door. Make sure that locking the doors from the driver's or pas-
senger side using the key activates all the actuators in the vehicle. This requires a slight modification to the door
lock harness. Mercedes-Benz and Audi 1985 and newer.
This system is found in the late-model Nissan Sentra, some Nissan 240SX, and Nissan 300ZX 1992-up. It is also
found in older Mitsubishi, and some early Mazda MPV’s.
■ Three-wire switches will have either a constant ground input or a constant (+)12V input, along with the
pulsed lock and unlock outputs to the factory relays.
■ Many BMW’s and VW’s have no external switch. The switches are inside the actuator, and instead of pulsing,
the proper wires will flip-flop from (+)12V to (-) ground as the door locks are operated.
■ Direct-wired switches will have a (+) 12V constant input and one or two (-) ground inputs, along with two
output leads going directly to the lock motors.
Use these instructions if the power door lock switch has four or five heavy-gauge wires. This type of switch has
two outputs that rest at (-) ground.
IMPORTANT! To interface with these systems, you must cut two switch leads. The relays must dupli-
cate the factory door lock switches’ operation. The master switch will have one or two ground
inputs, one (+)12V input, and two switch outputs going directly to the slave switch and through
to the motors. These outputs rest at (-) ground. The lock or unlock wire is switched to (+)12V, while
the other wire is still grounded, thus completing the circuit and powering the motor. This will dis-
connect the switch from the motor before supplying the motor with (+)12V, avoiding sending
(+)12V directly to (-)ground.
It is critical to identify the proper wires and locate the master switch to interface properly. Locate wires that
show voltage when the switch is moved to the lock or unlock position. Cut one of the suspect wires and check
operation of the locks from both switches. If one switch loses all operation in both directions then you have cut
one of the proper wires and the switch that is entirely dead is the master switch. If both switches still operate
in any way and one or more door motors have stopped responding entirely, you have cut a motor lead. Reconnect
it and continue to test for another wire. Once both wires have been located and the master switch identified,
cut both wires and interface as shown below.
WARNING! If these are not connected properly, you will send (+) 12 volts directly to (-) ground,
possibly damaging the control module or the factory switch.
testing reversing polarity door lock systems
at the switch
type F: one-wire system - cut to lock, ground to unlock
type E: electrically activated vacuum systems
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