Hummer H2. Manual — part 180

Passlock(tm) Sensor

The Passlock(tm) sensor is inside the ignition cylinder lock housing. The Passlock(tm) sensor contains 2 hall
effect sensors. The tamper hall effect sensor is on the top. The security hall effect sensor is under the tamper
hall effect sensor. Both of the hall effect sensors monitor the magnet of the lock cylinder through an opening.
The tamper hall effect sensor is physically placed on top of the security hall effect sensor. This arrangement
enables the tamper hall effect sensor to engage first if an intruder attempts to bypass the Passlock(tm) sensor by
placing a large magnet around that area of the steering column. There is a tamper resistor inside the Passlock
(tm) sensor in order to help prevent tamper to the system. Passlock(tm) equipped vehicles have a selection of 10
different security resistors ranging from 0.5K ohms up to 13.6K ohms. Installing one of the security resistors
inside the Passlock(tm) sensor will generate a unique Passlock(tm) code. All 10 combinations of the Passlock
(tm) sensor have the same part number. However, you cannot simply replace the Passlock(tm) sensor and
expect the system to operate properly. Always start by performing the Diagnostic System Check first and
following the instructions.

Body Control Module

The Body Control Module (BCM) contains the theft deterrent system logic. The BCM reads the Passlock(tm)
data from the Passlock(tm) sensor. If the Passlock(tm) data is correct, the BCM will pass theft. The BCM will
then transmit the fuel continue password to the VCM/PCM.

During the tamper mode the vehicle may start. The vehicle will then stall. If the BCM receives the wrong
Passlock(tm) data, the VTD will immediately go into the tamper mode. The tamper mode will lock-out the
vehicle fuel injectors for 10 minutes. The SECURITY indicator will flash while the VTD is in the tamper mode.

If the Passlock(tm) sensor sends a correct password to the BCM when the ignition is in the ON position, the
BCM will send a fuel enable signal to the VCM/PCM. The VCM/PCM will not disable the fuel due to any
BCM message for the remainder of the ignition cycle.

SECURITY Telltale

The SECURITY telltale appears on the message center inside the instrument cluster. If the SECURITY telltale
flashes or if the SECURITY telltale lights continuously during the vehicle operation, refer to the system
diagnosis.

Vehicle/Powertrain Control Module

The VCM/PCM communicates with the BCM over the Class 2 serial data line. When the BCM determines a no
start condition, it sends a Class 2 serial data password to the VCM/PCM in order to disable the fuel injection
system. If the BCM receives the expected voltage from the Passlock(tm) sensor, the BCM sends a class 2 serial
data password to the VCM/PCM in order to enable the fuel injection system. The VCM/PCM then allows the
vehicle to start correctly. If the Class 2 serial data password from the BCM to the VCM/PCM is not within the
Vehicle Security Status Message, the fuel injectors will shut OFF during a start attempt. The SECURITY
telltale will be illuminated for 10 minutes. If the VCM/PCM does not receive the same password from the BCM
as the last learned one, the vehicle will start and then stalls due to the Fuel Lockout.

Fuel Lockout Cycle

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Theft Deterrent - Hummer H2

The Passlock(tm) system has a lockout cycle of approximately 10 minutes. Once the vehicle is in the lockout
cycle, the vehicle remains in the lockout cycle for 10 minutes, even if the ignition switch is turned from the
RUN position to the OFF position.

The Passlock(tm) system uses the lockout cycle in order to synchronize all of the Passlock(tm) components
when any Passlock(tm) related part is changed. The Passlock(tm) system requires 3 consecutive lockout cycles
in order to complete the 30 minute learn procedure for a changed component.

Changing the Passlock(tm) Components

The design of the Passlock(tm) system is to prevent theft even if the various theft deterrent parts change. The
parts that can no longer be changed without the possibility of going into a tamper mode are:

z

The Passlock(tm) sensor

z

The BCM

z

The VCM/PCM

If you replace any of these parts the vehicle may start and stall for 10 minutes. This is the long tamper mode. If
this occurs, the system must go through a long tamper mode cycle. During this time the SECURITY telltale will
be flashing for the full 10 minutes and the DTC B3031 will be set. The BCM and the VCM/PCM require the
full 10 minutes in order to complete a learn cycle. The ignition switch must remain in the RUN position until
the SECURITY telltale stops flashing. You will need to repeat the cycle if the ignition switch does not remain
in the RUN position. When replacing any of the above parts it is recommended to perform the Programming
Theft Deterrent System Components procedure.

The design of the Passlock(tm) system is to prevent the vehicle operation if the proper ignition key is not used
in order to start the vehicle. The mechanical key, in normal operation, will turn the ignition lock cylinder. The
Passlock(tm) sensor monitoring the position of the lock cylinder will relay the Passlock(tm) data to the body
control module (BCM). The BCM will determine the validity of the Passlock(tm) data. The BCM will send a
fuel continue password to the vehicle/powertrain control module (VCM/PCM). When the VCM/PCM receives
the correct password the VCM/PCM allows the fuel injectors to operate normally. The Passlock(tm) system
requires the VCM/PCM and the BCM to communicate the various functions in order to operate. These
functions transmit over the class 2 serial data line. For an explanation of the class 2 serial data description and
operation, refer to Data Link Communications Description and Operation in Data Link Communications.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Special Tools

Illustration

Tool Number/Description

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Theft Deterrent - Hummer H2

J 39200

Digital Multimeter

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Theft Deterrent - Hummer H2

2004 ACCESSORIES & EQUIPMENT

Body Control System - Hummer H2

SCHEMATIC AND ROUTING DIAGRAMS

BODY CONTROL SYSTEM SCHEMATICS

Fig. 1: Power, Ground, and Serial Data Circuits
Courtesy of GENERAL MOTORS CORP.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Body Control System - Hummer H2