Chevrolet Silverado / GMC Sierra. Manual - part 670
Symptom List
Refer to Air Bag Indicator Circuit Malfunction in order to diagnose the symptom.
Refer to Passenger Presence System Indicator Circuit Malfunction in order to diagnose the
symptom.
AIR BAG INDICATOR CIRCUIT MALFUNCTION
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
When the ignition is turned ON, the instrument panel cluster (IPC) flashes the AIR BAG
indicator 7 times. The inflatable restraint sensing and diagnostic module (SDM) performs
diagnostic tests on the SIR system and then commands the IPC to turn the AIR BAG indicator
OFF if no SIR malfunction exists. The AIR BAG indicator is controlled by the SDM via serial
data communications. If the ignition 1 voltage is outside of the normal operating voltage range 9-
16 volts, the SDM will command the IPC to turn the AIR BAG indicator ON with no DTCs
present then disables all deployment loops.
Diagnostic Aids
A DTC B1370 may set if the ignition 1 circuit is outside the 9-16 volts range.
Reference Information
Schematic Reference
SIR Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
SIR System Description and Operation
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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 Verification
1. Ignition ON, use the scan tool to request the SIR data list display. Observe the Battery
Voltage Parameter. The battery voltage on the scan tool should read 9-16 volts.
If the voltage is less than 9 volts, refer to Diagnostic System Check - Vehicle .
2. Ignition ON, monitor the IPC. The SIR warning indicator should flash then turn OFF.
Verify that the SIR warning indicator flashes and then turns OFF.
If the SIR warning indicator continually flashes then reprogrammed the SDM.
3. Using the scan tool, go to Body and Accessories, then go onward to Special Functions to
Instrument Panel Cluster, and then go to Display Test. In the Display Test mode you can
turn ON or OFF all the instrument panel indicators when commanded ON. Commanded the
IPC indicators ON. The AIR BAG indicator should turn ON.
If the AIR BAG indicator does not turn ON, replace the IPC.
4. If the scan tool commands the AIR BAG indicator ON and OFF, replace the SDM.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
SIR/SRS Wiring Repairs
Control Module References for IPC and SDM replacement, setup, and programming
PASSENGER PRESENCE SYSTEM INDICATOR CIRCUIT MALFUNCTION
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The PASSENGER AIR BAG ON/OFF indicators are used to notify the driver when the
Passenger Presence System (PPS) has enabled or disabled the instrument panel (I/P) inflator
module. When the ignition is turned ON, the PPS module will commands both PASSENGER
AIR BAG ON/OFF indicators ON for 5 seconds. The PPS module conducts tests on the PPS
components and circuits while both PASSENGER AIR BAG ON/OFF indicators are ON. If no
malfunctions are detected, the PPS module will turn the PASSENGER AIR BAG indicator ON
or OFF, depending on the status of the PPS. If a malfunction is detected, the PPS module will
store a DTC, default the PPS to the OFF state, and communicate with the sensing and diagnostic
module (SDM) that a DTC has been set. The SDM will request the instrument panel cluster (IPC)
to turn the AIR BAG indicator ON to notify the driver of a malfunction.
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
SIR/SRS Wiring Repairs
Scan Tool Reference
Control Module References
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the inflatable restraint passenger air bag
On/Off indicator.
2. Ignition OFF, test for less then 1 ohm between the ground circuit terminal 2 and ground.
If greater then the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 4 and
ground.
If the test lamp does not illuminate, test the ignition circuit for a short to ground or an
open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test
or replace the inflatable restraint passenger air bag On/Off indicator.
4. Connect a test lamp between the control circuit terminal 3 and the ignition circuit terminal
4. With the passenger seat unoccupied, then occupied the test lamp should switch states
within 5 seconds.
If the test lamp is always on, test the control circuit for a short to ground. If all circuits
test normal replace the IPC.
If the test lamp is always off, test the control circuit for a short to voltage or an
open/high resistance. If all circuits test normal replace the IPC.
5. Connect a test lamp between the control circuit terminal 1 and the ignition circuit terminal
4. With the passenger seat unoccupied, then occupied the test lamp should switch states
within 5 seconds.
If the test lamp is always on, test the control circuit for a short to ground. If all circuits
test normal replace the IPC.
If the test lamp is always off, test the control circuit for a short to voltage or an
open/high resistance. If all circuits test normal replace the IPC.
IMPORTANT: When removing connectors inspect for damage or corrosion.
Damage or corrosion in the following requires repair or
replacement of the affected.
PPS module
PPS module wiring harness
The IPC module
The IPC module wiring harness
SDM
SDM wiring harness
2008 Chevrolet Silverado 1500
2008 RESTRAINTS Supplemental Inflatable Restraints - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado