Chevrolet Silverado / GMC Sierra. Manual - part 659
RF Seat Belt Sensor Circuit Short to Battery
DTC B0073 02
RF Seat Belt Sensor Circuit Short to Ground
DTC B0073 04
RF Seat Belt Sensor Circuit Open Circuit
DTC B0073 06
RF Seat Belt Sensor Circuit Short To Ground or Open Circuit
DTC B0073 08
RF Seat Belt Sensor Circuit Signal Invalid
Diagnostic Fault Information
Circuit/System Description
The inflatable restraint seat belt switch is within the seat belt retractor and provides an input to
the inflatable restraint sensing and diagnostic module (SDM). The SDM supplies a low reference
circuit and a seat belt switch signal circuit to determine a buckled or unbuckled condition. The
SDM monitors the seat belt switch circuits, and if a fault is detected a DTC will be set.
Conditions for Running the DTC
Ignition voltage is between 9-16 volts.
Conditions for Setting the DTC
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Seat Position Sensor Low
Reference
-
B0072 04,
B0073 04
B0072 04 B0079 01
B0072 08
Seat Belt Switch Left Signal
B0073 02,
06
B0072 04 B0072 04 B0072 01
B0072 08
Seat Belt Switch Right Signal
B0073 02,
06
B0073 04 B0073 04 B0073 01
B0073 08
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
B0072 01, B0073 01
The SDM detects the seat switch signal circuit or low reference circuit is shorted to voltage for
500 milliseconds.
B0072 02, B0073 02
The SDM detects the seat switch signal circuit or low reference circuit is shorted to ground for
500 milliseconds.
B0072 04, B0073 04
The SDM detects the seat switch signal circuit or low reference circuit is open for 500
milliseconds.
B0072 06, B0073 06
The SDM detects the seat switch signal circuit or low reference circuit is shorted to ground or an
open for 500 milliseconds.
B0072 08, B0073 08
The SDM detects an invalid signal in the seat switch signal circuit.
Action Taken When the DTC Sets
The SDM commands the AIR BAG indicator ON.
The SDM will store a DTC.
Conditions for Clearing the DTC
The condition for setting the DTC no longer exists.
A history DTC will clear once 100 malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
Seat Belt Schematics
Connector End View Reference
Component Connector End Views
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Electrical Information Reference
Circuit Testing
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Connector Repairs
Circuit/System Testing
1. Ignition OFF, disconnect the seat belt switch connector.
2. Test for less than 1.0 ohm between low reference terminal B and ground.
If greater than specified, test the low reference circuit for open/high resistance. If the
circuit tests normal, replace the SDM.
3. Ignition ON. Test for 1.0 - 1.6 volts between the signal circuit terminal A and ground.
If less that the specified range, test the signal circuit for open/high resistance or a short
to ground. If the circuit tests normal, replace the SDM.
If greater that the specified range, test the signal circuit for a short to voltage.
4. If the circuits test normal, replace the seat belt retractor.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Seat Belt Retractor Pretensioner Replacement - Front (Regular Cab) or Seat Belt
Retractor Pretensioner Replacement - Front (Extended Cab) or Seat Belt Retractor
Pretensioner Replacement - Front (Crew Cab)
IMPORTANT:
The seat belt switch is not serviced separately. The seat belt
retractor with the seat belt switch must be serviced as a
complete unit.
When removing connectors, inspect for damage or corrosion.
Damage or corrosion in the following requires repair or
replacement of the affected component/connector:
The SDM module
The seat belt switch wiring harness connector
The seat belt switch
The SDM wiring harness connector
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
SIR/SRS Wiring Repairs
Control Module References for SDM and PPS replacement, setup, and programming
DTC B0074
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using the diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B0074 03
Passenger Occupant Classification Sensor Circuit Voltage Below Threshold
DTC B0074 07
Passenger Occupant Classification Circuit Voltage Above Threshold
DTC B0074 08
Passenger Occupant Classification Circuit Signal Invalid
Diagnostic Fault Information
Circuit/System Description
The passenger presence system (PPS) uses a silicone filled sensor pad located underneath the
passenger seat foam cushion and is connected by a hose clamp to a pressure sensor. The weight of
the occupant sitting in the front passenger seat is measured as a pressure change within the
bladder by the pressure sensor. The pressure sensor is a 3-wire sensor consisting of a power,
ground, and signal circuit. The PPS continually monitors itself and if a fault in this circuit occurs,
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Pressure Sensor Low Reference
-
B0074 03
B0074 03
-
Pressure Sensor Signal
B0074 07
B0074 03, 07 B0074 03, 07
B0074 03
Pressure Sensor Voltage
Reference
B0074 07
B0074 07
B0074 07
B0074 03
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado