Crime Guard 328i3 Installation Manual page 22

5 Wire Reversal Systems:
of all differs from the negative and positive pulse systems in the fact that there
are no relays or doorlock control unit.* As a side note, the 5 Wire Reversal
system is also the type of circuit found after the relays in the other two types
of power doorlock systems. The five wires found at the doorlock switch are:
- One is Positive 12 Volts at all times.
- Two show Ground at all times.
- The remaining two are Grounded until the switch is operated, with
one wire changing from Ground to Positive 12 Volts upon "lock" and
the other changing from Ground to Positive 12 Volts upon "unlock".
The 5 Wire Reversal system resembles the 3 Wire Positive system, as it
also shows Positive 12 Volt pulses as it is operated, but the 5 Wire Reversal
system's wires rest at a full chassis Ground when not in operation. In this type
of system, the switches themselves supply the positive voltage directly to
the doorlock actuators, and, more importantly, provide the return ground
path. The important thing to remember is the wires in this system rest at
ground, which means that the wires must be "opened", or cut, to make the
connections. As in the example explained in the 3 Wire Positive section, a
DMM would read around 0 ohms on the 5 Wire Reversal's target wires.
The correct target wires are found between the vehicle's power doorlock
switches. These two wires are both routed to the doorlock actuators and are
connected to either end of the actuator's motor winding. When either switch
is pushed to one position, one of these two wires will have 12 volts. This
voltage flows through the wire to the actuator's motor winding, and since the
other wire is still resting at ground an electrical circuit is completed. When
the switch is pushed to the opposite position the electrical flow is reversed.
When the correct wires are found, they must be cut. Notice in the diagram
(following page) that the driver's switch is the primary switch and referred to
as the "switch" wires. The wires that go to the secondary switch are referred
to as the "motor" wires. Even though the cut is made between the switches,
the two sides are still correctly called the "switch" and the "motor" sides, with
consideration of "Primary" and "Secondary" switch.
* As always with the wide array of vehicle power doorlocking systems, it is
possible to encounter variations, especially in the case of an existing
aftermarket doorlock system. A vehicle having a 5 Wire Reversal system does
not absolutely rule out the absence of existing relays, most notably if the
vehicle is pre-equipped with a remote entry or automatic locking system.
The 5 Wire Reversal system first
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