GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Seville 🢒 Body and Accessories 🢒 Wiring Systems 🢒 SIR Diagnostic System Check

Caution: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified in this manual and the instructions given in this manual. Failure to use the specified equipment as instructed could cause air bag deployment, personal injury to you or someone else, or unnecessary SIR system repairs.

These diagnostic procedures will help you to find and repair SIR system malfunctions. This service category also contains information for repairing SIR system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:

  1. Perform the SIR Diagnostic System Check. All SIR diagnostics must begin with the SIR Diagnostic System Check. The SIR Diagnostic System Check determines the following:
    2. • Proper AIR BAG warning lamp operation
    • Ability of the SDM to communicate through the Data Link Connector (DLC)
    • Existence of SIR Diagnostic Trouble Codes (DTC)
    • Existence of State Of Health (SOH) Diagnostic Trouble Codes (DTC)
  2. Refer to the diagnostic table as directed by the SIR Diagnostic System Check. The diagnostic tables will help enable you to diagnose any SIR system malfunction. Bypassing these procedures may result in the following:
    3. • Extended Diagnostic Time
    • Incorrect Diagnosis
    • Incorrect Parts Replacement
  3. Repeat the SIR Diagnostic System Check after you perform any repair or diagnostic procedures. This will verify that you correctly performed the repair. This will also ensure that no other malfunctions exist.

Circuit Description

The ignition switch supplies Ignition 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal 3 using the SIR Fuse. The ignition switch also supplies Ignition 1 voltage to the instrument cluster (IPC). When the ignition switch is first turned to the ON position, the IPC responds by flashing the AIR BAG warning lamp seven times. The SDM performs tests on the SIR system while the IPC is flashing the warning lamp. If the SDM detects no malfunctions, the SDM commands the IPC to turn the warning lamp OFF. If the SDM detects a malfunction, the SDM commands the IPC to turn the warning lamp ON. If the IPC receives no message from the SDM, the IPC will turn the warning lamp ON.

Diagnostic Aids

You must diagnose the diagnostic trouble codes in the order specified by the SIR Diagnostic System Check. Failure to do so may result in the following:

    • Extended Diagnostic Time
    • Incorrect Diagnosis
    • Incorrect Parts Replacement

If the AIR BAG warning lamp does not flash seven times when the ignition switch is turned to the ON position, then the IPC is not operating correctly.

If a State Of Health (SOH) DTC is present, refer to Body Control Systems.

Test Description

Refer to step numbers on the diagnostic table.

  1. The Instrument Cluster (IPC) should flash the AIR BAG warning lamp seven times after the ignition switch is first turned to the ON position.

    2.

  2. The AIR BAG warning lamp should turn OFF after flashing seven times.

    3.

  3. This test checks for the proper operation of the Class 2 serial data line.

    4.

  4. This test will identify the stored diagnostic trouble codes and whether they are current or history.

    5.

  5. This test checks for the proper operation of the Class 2 serial data line. This test also identifies any stored history diagnostic trouble codes.

Step

Action

Value(s)

Yes

No

1

Note the AIR BAG warning lamp while turning the ignition switch to the ON position.

Does the AIR BAG warning lamp flash seven times?

--

Go to Step 2

Go to Instrument Cluster System Check in Instrument Panel, Gauges and Console

2

Note the AIR BAG warning lamp after it flashed seven times.

Does the AIR BAG warning lamp go OFF and stay OFF for 30 seconds?

--

Go to Step 5

Go to Step 3

3

  1. Turn the ignition switch OFF.
  2. Connect a scan tool to the Data Link Connector. Follow the directions in the instruction manual of the scan tool.
  3. Turn the ignition switch to the ON position.
  4. Request the SIR Diagnostic Trouble Code (DTC) display.

Is a current DTC displayed?

--

Go to Step 4

Go to Lamp Flashes Seven Times, Stays On, No DTCs Set

4
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order, specifying as current or history.
    3. • When DTC B1124 is set, go to DTC B1124 Driver/Pass. Deploy. Loop Short to GND .
    • When DTC B1125 is set, go to DTC B1125 Driver/Pass Deploy Loop Short to Voltage .
    • When DTC B1145 is set, go to DTC B1145 Driver/Pass Pretens. Loop Short to Volt .
    • When DTC B1151 is set, go to DTC B1151 Deployment Commanded - Frontal .
  3. Diagnose the remaining DTCs from lowest to highest. Refer to Diagnostic Trouble Code (DTC) List/Type .
  4. When only history DTCs exist, Go to Diagnostic Aids for that specific DTC. Refer to Diagnostic Trouble Code (DTC) List/Type . A history DTC indicates the malfunction has been repaired or is intermittent.

Has current DTC diagnosis been performed and the current DTCs cleared?

--

Go to Step 1

--

5

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the Data Link Connector. Follow the directions in the instruction manual of the scan tool.
  3. Turn the ignition switch to the ON position.
  4. Request the SIR Diagnostic Trouble Code (DTC) display.

Is a history DTC displayed?

--

Go to Step 7

Go to Step 6

6

Does the scan tool indicate no data received?

--

Go to Data Link Communications System Check in Wiring Systems

System OK

7
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order specifying as history. Do not clear the DTCs at this time.
  3. When DTC B1124 is set, go to DTC B1124 Driver/Pass. Deploy. Loop Short to GND .
  4. When DTC B1125 is set, go to DTC B1125 Driver/Pass Deploy Loop Short to Voltage .
  5. When DTC B1145 is set, go to DTC B1145 Driver/Pass Pretens. Loop Short to Volt .
  6. When DTC B1152 is set, go to DTC B1152 Data Area Full .
  7. When DTC B1171 is set, go to DTC B1171 Internal SDM Failure .
  8. For all other DTCs, Go to Diagnostic Aids for that specific DTC. Refer to Diagnostic Trouble Code (DTC) List/Type . A history DTC indicates the malfunction has been repaired or is intermittent. State Of Health (SOH) DTCs are diagnosed in Body Control System. Refer to Diagnostic Trouble Code (DTC) List/Type .

Has the diagnosis been performed and the DTCs cleared?

--

Go to Step 1

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