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© 2004 Directed Electronics, Inc.
N556U 09/04
The 556U immobilizer interface module is used when installing remote start products in vehicles equipped with
an RF (Radio Frequency) based immobilizer system. This type of system uses a small chip imbedded in the igni-
tion key, called a transponder, to transmit a very low powered RF signal. This signal is picked up through an
antenna (or coil) around the ignition switch which is then sent to the immobilizer’s transceiver. Once the correct
signal is received, the immobilizer will enable the ignition and/or fuel systems. If an attempt is made to start
the vehicle and the transceiver does not receive a valid code, the ignition and sometimes the fuel systems are
disabled. The immobilizer system will then render the remote start useless. The 556U bypasses the immobilizer
system only while the remote start is in use, maintaining the factory system’s integrity. When the remote start
system is not in use the factory immobilizer remains fully functional.
R
REED
D ((+
+)) 1
12
2 V
Vo
olltt IIn
np
pu
utt:: Connect this wire to a fused source of constant 12V.
B
BLLU
UEE ((--)) SSttaattu
uss IIn
np
pu
utt:: Connect this wire to the remote start negative (-) status output.
P
PIIN
NK
K ((+
+)) IIg
gn
niittiio
on
n IIn
np
pu
utt:: Connect this wire to the vehicle’s true ignition output. (Refer to
Latching Input, page 7.)
B
BLLA
ACCK
K ((--)) CCh
haassssiiss G
Grro
ou
un
nd
d IIn
np
pu
utt:: Connect this wire to the vehicle’s chassis ground.
V
VIIO
OLLEETT ((+
+)) K
Keeyysseen
nssee IIn
np
pu
utt:: Connect this wire to the vehicle’s positive keysense output wire. (Refer to
Key Sense
Inputs, page 7.)
G
GR
REEEEN
N ((--)) K
Keeyysseen
nssee IIn
np
pu
utt:: Connect this wire to the vehicle’s negative keysense output wire. (Refer to
Key Sense
Inputs, page 7.)
B
BLLA
ACCK
K aan
nd
d B
BLLA
ACCK
K//R
REED
D W
Wiirreess:: Both of these are antenna ring wires.
B
BLLA
ACCK
K//W
WH
HIITTEE:: Refer to alternate wiring diagram.
33--PPiinn H
Haarrnneessss
66--PPiinn H
Haarrnneessss
PPrroodduucctt DDeessccrriippttiioonn
556U Immobilizer Interface