GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Epica 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1103

Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing these tests, ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

The SDM inspects the wiring connection to each inflator by letting the perpetual current flow through the internal circuit and verify the resistance. If the voltage is out of range, the SDM is unable to inspect the air bag system properly.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1103 SIR Serial Communications Fault

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The voltage supplied from the battery maintains lower than 10.6 volts for 16 seconds.

Action Taken When the DTC Sets

The SDM commands the air bag indicator ON.

Conditions for Clearing the DTC

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

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

Step

Action

Values

Yes

No

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform a Diagnostic System Check - Vehicle?

 

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect fuse F10.

Is the fuse blown?

--

Go to Step 3

Go to Step 4

3

Replace fuse F10.

Is the replacement complete?

--

Go to Step 11

--

4
  1. Confirm the ignition switch is ON.
  2. Measure the voltage from fuse F10.

Is the voltage less than the specified value?

10.6 V

Go to Step 5

Go to Step 6

5

Repair the power supply and the wiring to fuse F10.

Is the repair complete?

--

Go to Step 11

--

6
  1. Confirm the ignition switch is OFF.
  2. Disconnect the connector of the steering wheel module coil.
  3. Disconnect the connector of the instrument panel (I/P) module.
  4. Disconnect the connector of the sensing and diagnostic module (SDM).
  5. Confirm the ignition switch is ON.
  6. Measure the voltage between terminal 26 of the SDM connector and the ground.

Is the voltage less than the specified value?

10.6 V

Go to Step 7

Go to Step 9

7
  1. Disconnect the C208.
  2. Confirm the ignition switch is ON.
  3. Measure the voltage from terminal 4 of C208.

Is the voltage less than the specified value?

10.6 V

Go to Step 8

Go to Step 10

8

Repair the wire between the fuse F10 and the terminal 4 of connector C208.

Is the repair complete?

--

Go to Step 11

--

9

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

Is the replacement complete?

--

Go to Step 11

--

10

Repair the wire between the SDM terminal 26 and the terminal 4 of connector C208.

Is the replacement complete?

--

Go to Step 11

--

11
  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 2

System OK