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© 2000 Directed Electronics, Inc. Vista, CA
Here is a test: Cut the wire which pulses (+)12V on lock, and then operate the switch to unlock.
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If all doors unlock, the vehicle uses Type A system.
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If you lose all door lock operation in both directions, you are operating the master switch in a Type C system.
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If you lose all door lock operation of one or more doors, but not all motors stop operating, and other doors
still work, you have cut a wire leading directly to one or more motors. You must instead find the actual wires
leading to the switch.
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, 1995 Cavalier/Sunfire 1993
and newer, Camaro/Firebird all use Type C door locks, and cannot be controlled without a 451M! Almost all domes-
tically-built Fords are Type C. Ford builds almost no Type A systems. Chrysler builds both Type A and Type C, so
care must be taken in determining the type of door locking system.
IMPORTANT!
Remember that the functions of these wires are reversed between Type A and Type B!
This system is common in many Toyota, Nissan, Honda, and Saturn models, 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 the functions of these wires reverse between Type A and Type B!
type B: (-) pulses from the switch to the factory relays
