GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C Sierra - 2WD 🢒 Body and Accessories 🢒 Instrument Panel, Gauges, and Console 🢒 Air Bag Indicator Circuit Malfunction

Circuit Description

When the ignition is turned ON, the instrument panel cluster (IPC) flashes the AIR BAG indicator seven times. The inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within the SIR system. If no SIR system malfunctions exists, the SDM will request the IPC to turn the AIR BAG indicator OFF after it has flashed seven times. The AIR BAG indicator is controlled by the SDM via Class 2 serial data.

Diagnostic Aids
    •  If Ignition 1 voltage is outside of the normal operating voltage range (9-16 volts), the AIR BAG indicator will come ON solid with no DTCs set.
    • The loss of serial data communication between the SDM and the instrument panel cluster (IPC) will cause the AIR BAG indicator to come ON solid. Refer to DTC U1001-U1254 in Data Link Communications.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if ignition 1 voltage to the SDM is more than 9 V.

    2.

  2. This step determines if ignition 1 voltage to the SDM is more than 16 V.

    3.

  3. Tests for an open or high resistance in the ignition 1 voltage circuit between the SDM and the SIR fuse.

    4.

  4. Tests for an open or high resistance in the ignition 1 voltage circuit that feeds the SIR fuse.

    5.

  5. Tests for an open or high resistance in the SDM ground circuit.

Step

Action

Value(s)

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform the Diagnostic System Check - SIR?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

Did you perform the Diagnostic System Check - Instrument Cluster?

--

Go to Step 3

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gages, and Console

3
  1. Turn OFF the ignition.
  2. Observe the AIR BAG indicator while turning the ignition ON.

Does the AIR BAG indicator flash seven times?

--

Go to Step 4

Go to Step 10

4

  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, request the ignition voltage parameter in the SIR data list.

Does the ignition voltage displayed measure more than the specified value?

9 V

Go to Step 5

Go to Step 6

5

Does the ignition voltage displayed measure more than the specified value?

16 V

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Test the ignition 1 voltage circuit between the SDM and the fuse block for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 7

7

Test the ignition 1 voltage circuit that feeds the SIR fuse for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8

Test the SDM ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Disconnect the SDM connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect the SDM connector for corrosion or damage. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

10
  1. Disconnect the IPC connector. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.
  2. Inspect the IPC connector for corrosion or damage. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11

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

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

--

Go to Step 13

--

13
  1. Reconnect all SIR and IPC system components.
  2. Verify that all components, connectors, and CPAs are properly mounted.

Have all SIR and IPC components been properly connected and mounted?

--

Go to Diagnostic System Check - SIR

--