Chevrolet Silverado / GMC Sierra. Manual — part 661
B0079 08
The SDM detects the SPS signal circuit is invalid for 500 milliseconds.
Action Taken When the DTC Sets
The SDM sets a DTC B0079.
The SDM defaults the SPS to seat rearward threshold.
The SDM commands the AIR BAG indicator ON.
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
SIR Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
SIR System Description and Operation
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
1. Ignition OFF, disconnect the harness connector at the SPS.
2. Disconnect the harness connector at the SDM.
3. Ignition ON, test for less than 1 volt between the SPS signal circuit terminal 29 and ground.
If greater than the specified range, test the circuit for a short to voltage.
4. Ignition ON, test for less than 1 volt between the SPS low reference circuit terminal 28 and
ground.
If greater than the specified range, test the circuit for a short to voltage.
5. Test for infinite resistance between the SPS signal circuit terminal 29 and ground.
If less than infinite resistance, test the circuit for a short to ground.
6. Test for less than 1 ohm of the SPS signal circuit between the SDM harness connector
terminal 29 and the SPS harness connector terminal 2.
If greater than the specified range, test the circuit for an open/high resistance.
7. Test for less than 1 ohm of the SPS low reference circuit between the SDM harness
connector terminal 28 and the SPS harness connector terminal 1.
If greater than the specified range, test the circuit for an open/high resistance.
8. If all circuits test normal, replace the SPS.
9. Reconnect all SIR components. Ignition ON, with a scan tool clear and recheck for DTCs.
If the front end sensor DTC returns and is current, replace the SDM. After
replacement, refer to Repair Verification.
Repair Procedures
Inflatable Restraint Front Passenger Position Sensor Replacement
SIR/SRS Wiring Repairs
Control Module References for SDM replacement, setup, and programming
Repair Verification
IMPORTANT: When removing connectors, inspect for damage or corrosion.
Damage or corrosion in the following requires repair or
replacement of the affected component/connector:
The Seat Position Sensor (SPS)
The Sensing and Diagnostic Module (SDM) module
The seat position sensor wiring harness connector
The SDM wiring harness connector
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Ignition ON, use the scan tool to clear the DTCs then recheck for DTCs. Verify no DTCs are set.
If DTC B0079 was current, replace the SDM.
DTC B0081
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 B0081 0F
Passenger Presence System Erratic
DTC B0081 39
Passenger Presence System Internal Electronic Failure
DTC B0081 3A
Passenger Presence System Incorrect Component Installed
DTC B0081 71
Passenger Presence System Invalid Serial Data Received
Circuit/System Description
When the ignition is turned ON, the passenger presence system (PPS) and the inflatable restraint
sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions. When the
SDM has completed the power-up mode, the SDM will establish communication with the PPS.
The SDM will also request the instrument panel cluster (IPC) to command both of the
PASSENGER AIR BAG ON/OFF indicators ON for 5 seconds. If the SDM determines the
correct PPS is installed and functioning normally, the SDM will turn the passenger side airbags
ON or OFF based on messages from the PPS. The SDM will also send a message to the IPC to
turn the appropriate PASSENGER AIR BAG ON/OFF indicator on.
Conditions for Running the DTC
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Ignition voltage is between 9-16 volts.
Conditions for Setting the DTC
All of the following conditions must exist for 5 seconds:
B0081 0F
The SDM has received a fault present message from the PPS.
The PPS is in assembly plant mode and the SDM is in production mode.
B0081 39
The SDM has received a critical malfunction message from the PPS.
B0081 3A
The SDM has received a message from the PPS which indicates a vehicle and PPS mismatch.
B0081 71
The SDM has received invalid or no serial data from the PPS.
Action Taken When the DTC Sets
The SDM commands the AIR BAG indicator ON, and the passenger air bag indicator to
display OFF.
The I/P module deployment loop will be disabled.
Conditions for Clearing the DTC
The condition for setting the DTC no longer exists and there is no activity on the low speed
serial data circuits.
A history DTC will clear once 100 malfunction-free ignition cycles have occurred.
Diagnostic Aids
If either the SDM or PPS were replaced, verify that the correct part numbers were used for the
vehicle application.
Reference Information
Schematic Reference
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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