Grand Cherokee 2WD V8-5.7L VIN 2 (2005)
Seat Belt Buckle Switch: Description and Operation
The seat belt switch for this model is actually a Hall Effect-type sensor. This sensor consists of a fixed-position, Hall Effect Integrated Circuit (IC) chip
and a small permanent magnet that is integral to the driver side front seat belt buckle. The driver side front seat belt buckle is located on a molded plastic
scabbard and secured along with the seat belt tensioner mechanism by a nut to the inboard side of the driver side front seat cushion frame. The seat belt
switch is connected to the vehicle electrical system through a two-lead pigtail wire and connector (1) on the driver side front seat belt buckle-half, which
is connected to a wire harness connector and take out of the seat wire harness. A radio noise suppression capacitor is connected in parallel with the IC
where the two pigtail wire leads connect to the IC pins.
The seat belt switch cannot be adjusted or repaired and, if faulty or damaged, the entire driver side front seat belt buckle-half and tensioner unit must be
replaced.
The seat belt switch is designed to provide a status signal to the seat belt switch sense input of the Occupant Restraint Controller (ORC) indicating
whether the driver side front seat belt is fastened. The ORC uses the seat belt switch input to determine the status of the driver side front seat belt. The
ORC then sends electronic messages to the ElectroMechanical Instrument Cluster (EMIC) to control the seat belt indicator based upon the status of the
seat belt switch input.
A spring-loaded slide with a small window-like opening is integral to the buckle latch mechanism. When a seat belt tip-half is inserted and latched into
the seat belt buckle, the slide is pushed downward and the window of the slide exposes the Hall Effect Integrated Circuit (IC) chip within the buckle. The
field of the permanent magnet induces a current within the chip. The chip provides this induced current as an output to the ORC. When the seat belt is
unbuckled, the spring-loaded slide moves upward and shields the IC from the field of the permanent magnet, causing the output current from the seat belt
switch to be reduced.
The seat belt switch receives a supply current from the ORC, and the ORC senses the status of the driver side front seat belt through its pigtail wire
connection to the seat wire harness. The ORC also monitors the condition of the seat belt switch circuit and will illuminate the airbag indicator in the
EMIC then store a Diagnostic Trouble Code (DTC) for any fault that is detected in the seat belt switch circuit. For proper diagnosis of the seat belt
switch, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
