GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 DeVille 🢒 Restraints 🢒 SIR 🢒 Lamp Flashes Seven Times, Stays On, No DTCs Set

Object Number: 235791 Size: MF

Circuit Description

When the ignition switch is first turned to RUN, the SIR Fuse applies battery voltage to the inflatable restraint sensing and diagnostic module (SDM) at the Ignition Positive Voltage input, terminal 3. Battery voltage is also applied to the instrument panel cluster (IPC). 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. The SDM commands the IPC over the Serial Data Line Class 2.

Diagnostic Aids

If the IPC receives no message from the SDM the IPC will do the following when the ignition is turned to RUN:

    • Flash the AIR BAG warning lamp seven times
    • Turn the warning lamp ON
    • Set DTC U1255 (Class 2 Initialization Error-IPC)
    • If the ignition is in the RUN position, has received at least one message from the SDM, and the IPC loses communication with the SDM, the IPC will set DTC U1088 and the SDM will set DTC U1096.

When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.

Test Description

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

  1. This test determines if the SDM can communicate with the scan tool.

    2.

  2. This test checks for sufficient Ignition Positive Voltage applied to the SDM.

  3. This test determines whether the Serial Data Line Class 2 is malfunctioning.

    4.

  4. This test checks for an open SIR Fuse.

    5.

  5. This tests determines whether a short-to-ground caused the SIR Fuse to open.

    6.

  6. This test determines whether the short-to-ground is due to a short in the wiring or internal to the SDM.

    7.

  7. This test checks for a disconnected SDM.

    8.

  8. This test checks for an open in the Ignition Positive Voltage circuit.

Air Bag Warning Lamp Flashes Seven Times, Stays On, And No DTCs Set

Step

Action

Value(s)

Yes

No

1

Was the SIR Diagnostic System Check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

Does the scan tool indicate no data received?

--

Go to Step 5

Go to Step 3

3

  1. Set the parking brake.
  2. Start the engine.
  3. Using the scan tool, read the SIR data list.

Is IGNITION more than the specified value?

7.8 V

Go to Step 4

Go to Step 5

4

Service the instrument panel cluster (IPC). Refer to Instrument Panel Cluster Replacement in Instrument Panel, Gauges, and Console.

Are the repairs complete?

--

Go to SIR Diagnostic System Check

--

5

Can you establish communications with other modules (PCM, IPC, etc.) on the Serial Data Line Class 2?

--

Go to Step 6

Go to Computer System Diagnosis

6

  1. Turn the ignition switch to the OFF position.
  2. Remove the SIR Fuse.
  3. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 12

Go to Step 7

7

  1. Replace the SIR Fuse.
  2. Turn the ignition switch to the RUN position for 10 seconds.
  3. Turn the ignition switch to the OFF position.
  4. Remove the SIR Fuse.
  5. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 11

Go to Step 8

8

  1. Disconnect the SDM.
  2. Replace the SIR Fuse.
  3. Turn the ignition switch to the RUN position for 10 seconds.
  4. Turn the ignition switch to the OFF position.
  5. Remove the SIR Fuse.
  6. Inspect the SIR Fuse.

Is the SIR Fuse good?

--

Go to Step 10

Go to Step 9

9
  1. Repair a short-to-ground condition in CKT 1139.
  2. Connect the SDM.
  3. Replace the SIR Fuse.

Are the repairs complete?

--

Go to Step 20

--

10
  1. Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Install the SIR Fuse.

Are the repairs complete?

--

Go to Step 20

--

11

Install the SIR Fuse.

Are the repairs complete?

--

Go to Step 20

--

12

Inspect the SDM harness connector.

Is the connector secure?

--

Go to Step 14

Go to Step 13

13
  1. Properly connect the SDM harness connector.
  2. Install the CPA.

Are the repairs complete?

--

Go to Step 20

--

14
  1. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors at the base of the steering column and behind the IP compartment.
  2. Disconnect the SDM.
  3. Check for proper connection to the SDM at terminal 3.

Is the SDM harness connector terminal damaged or corroded?

--

Go to Step 15

Go to Step 16

15

Replace the SDM harness connector. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 20

--

16

Inspect the SDM terminals for damage or corrosion.

Are any terminals damaged or corroded?

--

Go to Step 17

Go to Step 18

17

Replace the inflatable restraint sensing and diagnostic module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Are the repairs complete?

--

Go to Step 20

--

18

Measure the resistance from the SDM harness connector terminal 3 to each terminal of the SIR Fuse fuseholder.

Is either resistance reading within the specified values?

0-5 ohms

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 19

19

Repair an open condition in CKT 1139.

Are the repairs complete?

--

Go to Step 20

--

20

Reconnect all the SIR system components, make sure all the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--