GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2009 🢒 Spark 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B0078

Circuit Description

The sensing and diagnostic module (SDM) provides a two-wire interface for the side impact sensor (SIS). When the ignition is turned ON, SIS operation consists of 3 modes as power-up mode, ID mode and normal mode. During ID mode, the SIS sends a sequence of ID/traceability information to SDM. The power mode and ID mode must be completed within 5 seconds of the SIS being powered by SDM. If ID/traceability information is not received and verified within 5 seconds, SDM will set a DTC.

During normal mode, the SIS transmits a State Of Health (SOH) message once a second. If the SDM receives no SOH message for 5 seconds, the SDM will also set a DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B0078 Right SIS Malfunction

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The passenger side air bag sensor is inoperative.

Action Taken When The DTC Sets

The SDM commands the AIR BAG indicator ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Step

Action

Yes

No

Warning: Refer to SIR Warning in the Preface section.

Schematic Reference: SIR Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn the ignition OFF.
  2. Wait 1 minute for the sensing and diagnostic module (SDM) charger to be discharged.
  3. Visually inspect for any damage of the passenger side air bag sensor wiring and connector.

Is the air bag wiring damaged?

Go to Step 4

Go to Step 3

3

Test the passenger side impact sensor (SIS) high and low circuits for an open or high resistance, short to voltage, short to ground, and short between circuits. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 7

Go to Step 5

4

Repair or replace the air bag wiring.

Is the repair complete?

Go to Step 7

--

5

Replace the passenger side air bag sensor. Refer to Inflatable Restraint Side Impact Sensor Replacement.

Did you complete the replacement?

Go to Step 7

--

6

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement

Did you complete the replacement?

Go to Step 7

--

7
  1. Reconnect all SIR components.
  2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 6

System OK