Chevrolet Silverado / GMC Sierra. Service 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