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20 © 1999 Directed Electronics, Inc. Vista, CA
neutral safety switch interface
Some vehicles combine the column shift mechanism and the mechanical neutral safety switch into one mechan-
ical part. In these vehicles, it is impossible to interface the remote start system before the neutral safety switch.
With this type of vehicle, if the vehicle is left in a drive gear and the remote start system is activated, the vehicle
will move and may cause damage to persons or property.
According to available information, vehicles known to be manufactured this way are most General Motors trucks,
sport utility vehicles and column shifting passenger vehicles. Available information also indicates that pre-1996
Dodge Dakota pickups with 2.5 liter motors are also manufactured this way.
GM vehicles that have the neutral safety switch built into the column shifter can usually be identified by a purple
starter wire. Typically, vehicles that use an outboard mechanical switch use a yellow wire from the ignition switch
to the mechanical switch and a purple wire from the mechanical switch to the starter itself. Remember, this is
only a rule of thumb and is not intended as a substitute for proper testing.
IMPORTANT! Please see vehicle Safety Check section of this guide for testing procedures.
Vehicles with the neutral safety switch built into the column shifter require that the shifter be placed in park in
order to remove the keys from the ignition. As a result, it is possible to use the key-in-ignition sense switch to
prevent remote starting if the keys are in the ignition. (See General Motors Trucks, SUVs and Column-Shifting
Passenger Cars and Pre-1996 Dodge Dakota Pickups with 2.5 Liter Motors diagrams in this section on how to accom-
plish this.) The first diagram applies to all General Motors vehicles as of the date of this guide’s publication. The
second diagram applies to all pre-1996 Dodge Dakota pickup trucks with 2.5 liter motors. This solution has one
side effect: If the customer inserts the key in the ignition with the driver's door open, the remote start system
will shut down. If this interface is used, it is important to inform the customer that the driver’s door must be
closed before inserting the key into the ignition when the remote start is active. This will allow the customer to
turn the key on and shut the remote start down by pressing the brake, without the key sense wire shutting down
the unit prematurely.
You must also connect the H3/4 BROWN (+) shut-down input to the yellow wire on the relay satellite
ribbon cable. This prevents the remote start system from activating if the key is left in the “run” position. You
must use diodes to isolate the ignition circuit from the brake switch circuit as shown in the following diagram.