© 1998 Directed Electronics, Inc. Vista, CA
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N438 7/98
Many domestically-made GM vehicles use Type A locks. However, many more GM vehicles are Type C than in pre-
vious years. The full-size pickups (1989-up), many of the S10 Blazers, the Corvette, '95 Cavalier/Sunfire 1993 -
and newer, Camaro/Firebird all use Type C door locks, and cannot be controlled without a 451M! Almost all
domestically-built Fords are Type C. Ford builds almost no Type A systems. Chrysler builds both Type A and Type
C, so use care.
Type B - (-) pulses from the switch to the factory relays
This system is common in many Toyotas, Nissans, Hondas, and Saturns, as well as Fords with the keyless-entry
system (some other Fords also use Type B).
The switch will have three wires on it, and one wire will test ground all the time. One wire will pulse (-) when the
switch locks the doors, and the other wire will pulse (-) when the switch unlocks the doors. This type of system is
difficult to mistake for any other type.
IMPORTANT! Remember that these wires'
functions reverse between Type A and Type B!
IMPORTANT! Remember that these wires'
functions reverse between Type A and Type B!
