Seat Belt Buckle Switch

DESCRIPTION Two different seat belt switches are used in the front seat buckles of this vehicle. The driver side uses a mechanical switch, while the passenger side is actually a Hall Effect-type sensor. The driver side switch is a small, normally open, single pole, single throw, leaf contact, momentary switch. The driver side seat belt switch is integral to the buckle of the driver side front seat belt buckle. The passenger side switch consists of a fixed-position, Hall Effect Integrated Circuit (IC) chip and a small permanent magnet that is integral to the passenger side front seat belt buckle. The front seat belt buckles (1) are located on a molded plastic scabbard and secured along with the seat belt buckle tensioner mechanism by a screw (2) near the back of the inboard front seat cushion frame. The seat belt switches are connected to the vehicle electrical system through a two-lead pigtail wire (3) and a four-way connector shared with the buckle tensioner squib circuits on the front seat belt buckle-half, which is connected to a wire harness connector and take out of the seat wire harness routed beneath the front seat cushion. On the passenger side, a one kilohm diagnostic resistor is connected in parallel with the IC where the two pigtail wire leads connect to the IC pins. The seat belt switches cannot be adjusted or repaired. If ineffective or damaged, the entire front seat belt buckle-half and tensioner unit must be replaced.

DESCRIPTION Two different seat belt switches are used in the front seat buckles of this vehicle. The driver side uses a mechanical switch, while the passenger side is actually a Hall Effect-type sensor. The driver side switch is a small, normally open, single pole, single throw, leaf contact, momentary switch. The driver side seat belt switch is integral to the buckle of the driver side front seat belt buckle. The passenger side switch consists of a fixed-position, Hall Effect Integrated Circuit (IC) chip and a small permanent magnet that is integral to the passenger side front seat belt buckle. The front seat belt buckles (1) are located on a molded plastic scabbard and secured along with the seat belt buckle tensioner mechanism by a screw (2) near the back of the inboard front seat cushion frame. The seat belt switches are connected to the vehicle electrical system through a two-lead pigtail wire (3) and a four-way connector shared with the buckle tensioner squib circuits on the front seat belt buckle-half, which is connected to a wire harness connector and take out of the seat wire harness routed beneath the front seat cushion. On the passenger side, a one kilohm diagnostic resistor is connected in parallel with the IC where the two pigtail wire leads connect to the IC pins. The seat belt switches cannot be adjusted or repaired. If ineffective or damaged, the entire front seat belt buckle-half and tensioner unit must be replaced.

Two different seat belt switches are used in the front seat buckles of this vehicle. The driver side uses a mechanical switch, while the passenger side is actually a Hall Effect-type sensor. The driver side switch is a small, normally open, single pole, single throw, leaf contact, momentary switch. The driver side seat belt switch is integral to the buckle of the driver side front seat belt buckle. The passenger side switch consists of a fixed- position, Hall Effect Integrated Circuit (IC) chip and a small permanent magnet that is integral to the passenger side front seat belt buckle. The front seat belt buckles (1) are located on a molded plastic scabbard and secured along with the seat belt buckle tensioner mechanism by a screw (2) near the back of the inboard front seat cushion frame.

The seat belt switches are connected to the vehicle electrical system through a two-lead pigtail wire (3) and a four-way connector shared with the buckle tensioner squib circuits on the front seat belt buckle-half, which is connected to a wire harness connector and take out of the seat wire harness routed beneath the front seat cushion. On the passenger side, a one kilohm diagnostic resistor is connected in parallel with the IC where the two pigtail wire leads connect to the IC pins.

The seat belt switches cannot be adjusted or repaired. If ineffective or damaged, the entire front seat belt buckle- half and tensioner unit must be replaced.

The driver side front seat belt switch is a hard wired input to the Totally Integrated Power Module (TIPM), which provides electronic driver side seat belt switch status messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Controller Area Network (CAN) data bus. The EMIC controls the seat belt indicator based upon these electronic driver side seat belt switch status message inputs.

When the driver side front seat belt tip-half is inserted into the seat belt buckle, the switch closes the path to ground; and, when the driver side front seat belt tip-half is removed from the seat belt buckle, the switch opens the ground path. The switch is actuated by the latch mechanism within the seat belt buckle.

The seat belt switch is connected in series between ground and the seat belt switch sense input of the TIPM. The seat belt switch receives ground at all times through its pigtail wire connection to the seat wire harness from a take out of the body wire harness. An eyelet terminal connector on the body wire harness ground take out is secured beneath a ground screw on the left cowl side inner panel, beneath the instrument panel. The TIPM monitors the condition of the driver seat belt switch circuits and will send an electronic message to illuminate the airbag indicator in the EMIC then store a Diagnostic Trouble Code (DTC) for any fault that is detected.

The hard wired circuits between the driver side seat belt switch and the TIPM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the switch or the electronic controls or communication between other modules and devices that provide features of the supplemental restraint system. The most reliable, efficient, and accurate means to diagnose the driver side seat belt switch or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

The passenger side front seat belt switch is a hard wired input to the Occupant Restraint Controller (ORC). 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 passenger side seat belt switch receives a clean ground from the ORC through a hard wired connection, and the ORC senses the status of the seat belt buckle by monitoring the modulation of voltage through its connection to the seat belt switch output. The ORC provides electronic passenger side seat belt switch status messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Controller Area Network (CAN) data bus. The EMIC controls the seat belt indicator based upon these electronic passenger side seat belt switch status message inputs. The ORC also monitors the condition of the passenger side seat belt switch circuits and will send an electronic message to illuminate the airbag indicator in the EMIC, then store a DTC for any fault that is detected.

The hard wired circuits between the passenger side seat belt switch and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the switch or the electronic controls or communication between other modules and devices that provide features of the supplemental restraint system. The most reliable, efficient, and accurate means to diagnose the passenger side seat belt switch or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

SEAT BELT TENSIONER