Positive Multiplex (Type G) - Viper 300 ESP Installation Manual

type G: positive multiplex
This system is most commonly found in Ford, Mazda, Chrysler and GM vehicles. The door lock switch or door key
cylinder may contain either one or two resistors. When interfacing with this type of door lock system, two relays
or a DEI 451M must be used. (See diagram below.)
single-resistor type
If one resistor is used in the door lock switch/key cylinder, the wire will pulse (+)12V in one direction and less
than (+)12V when operated in the opposite direction.
two-resistor type
If two resistors are used in the factory door lock switch/key cylinder, the switch/key cylinder will read less than
(+)12V in both directions.
determining the proper resistor values
To determine the resistor values, the door lock switch/key cylinder must be isolated from the factory door lock
system. For all testing, use a calibrated digital multimeter that is set to ohms.
1. Cut the output wire from the door lock switch/key cylinder in half.
2. Test with the meter from the switch side of the cut door lock switch/key cylinder wire to a reliable constant
(+)12V source. Some good constant (+)12V references are the power input source to the door lock switch/key
cylinder, the ignition switch power wire, or the (+) terminal of the battery.
3. Operate the door lock switch/key cylinder in both directions to determine the resistor values. If the multi-
meter displays zero resistance in one direction, no resistor is needed for that direction.
4. Once the resistor value(s) is determined, refer to the wiring diagram for proper wiring.
© 2000 Directed Electronics, Inc. Vista, CA
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