GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Eldorado 🢒 Restraints 🢒 SIR 🢒 DTC B1124

Circuit Description

When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM measures the ignition positive voltage in order to ensure that the voltage is within the respective normal voltage range. During a frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the inflatable restraint steering wheel module. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in non-volatile memory.

Conditions for Running the DTC

Ignition 1 Voltage is within the normal operating voltage range.

Conditions for Setting the DTC

Steering wheel module or IP module deployment loops are not less than 2.2 volts for 500 milliseconds.

Action Taken When the DTC Sets

The SDM commands the AIR BAG warning indicator ON via Class 2 serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids
    • The SDM wiring harness connector.
    • The wire to terminal connection, open, or short in the steering wheel module high and/or low circuit.
    • The wire to terminal connection, open, or short in the IP module high and/or low circuit.

If any of the above conditions are found refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Noting the value of the driver senselo and the passenger senselo during diagnosis can be helpful in determining if an intermittent condition exists. An intermittent open in the inflatable restraint steering wheel module coil could also set this DTC. In order to test for a bad inflatable restraint steering wheel module coil, monitor the driver senselo while you turn the steering wheel back and forth when you turn ON the ignition switch. If the driver senselo changes while you are turning the steering wheel, a malfunction in the inflatable restraint steering wheel module coil is likely.

Test Description

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

  1. Test to see if the malfunction is caused by the steering wheel module coil and/or steering wheel module.

    2.

  2. Tests for a short to ground the steering wheel module high and steering wheel module low circuits.

    3.

  3. Tests for a short to ground the IP module high and IP module low circuits.

Step

Action

Value(s)

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform A Diagnostic System Check - SIR?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint steering wheel module coil in-line connector. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  3. Disconnect inflatable restraint IP module in-line connector. Refer to Inflatable Restraint Instrument Panel Module Replacement .
  4. Inspect the component and harness sides of the steering wheel module coil in-line connector and IP module for damage or corrosion that may cause a short to ground in the high and low circuits. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Does the IP module or steering wheel module coil in-line connectors exhibit any signs of damage or corrosion?

--

Go to Step 3

Go to Step 4

3
  1. If the component side of the IP module connector is damaged, the IP module must be replaced. Refer to Inflatable Restraint Instrument Panel Module Replacement .
  2. If the steering wheel module coil in-line connector is damaged, the steering wheel module coil must be replace. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  3. If the wiring harness side of IP module or steering wheel module coil in-line connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

--

4
  1. Reconnect IP and steering wheel modules in-line connectors.
  2. Verify that the connector position assurance (CPA) is properly installed.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC B1124 is current?

--

Go to Step 5

Go to Diagnostic Aids

5
  1. Turn OFF the ignition.
  2. Disconnect the in-line connector that connect steering wheel module coil to vehicle wiring harness.
  3. Install the J 38715-A SIR Load Tool to the wiring harness side of in-line connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request SIR data List display, read the driver frontal low voltage DRIVER SENSELO.

Does the scan tool indicate that DRIVER SENSELO is less than the specified value?

2.2 V

Go to Step 9

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Remove the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Disconnect the J 38715-A from the driver in-line connector.
  4. Connect the driver in-line connector.
  5. Install the J 38715-A to the upper steering wheel module coil connector.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request SIR data List display, read the driver frontal low voltage DRIVER SENSELO.

Does the scan tool indicate that DRIVER SENSELO is less than the specified value?

2.2 V

Go to Step 8

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Replace the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

8
  1. Turn OFF the ignition.
  2. Replace the steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

--

Go to Step 15

--

9

  1. Turn OFF the ignition.
  2. Disconnect the IP module connector.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Disconnect the J 38715-A .
  5. Test steering wheel module high and steering wheel module low circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 11

10
  1. Reconnect steering wheel module connector.
  2. Turn OFF the ignition.
  3. Disconnect the IP module connector. Refer to Inflatable Restraint Instrument Panel Module Replacement .
  4. Connect the J 38715-A SIR Driver/Passenger Load Tool to the harness side of the IP module connector. Use PASSENGER INFLATOR connector.
  5. Reconnect the SDM connector.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request SIR data list display.
  8. Read the passenger low voltage PASS. SENSELO.

Does the scan tool indicate that PASS. SENSELO is less than the specified value?

2.2 V

Go to Step 12

Go to Step 11

11
  1. Turn OFF the ignition.
  2. Replace the IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

12

  1. Turn OFF the ignition.
  2. Disconnect the SDM.
  3. Disconnect the J 38715-A .
  4. Test IP module high and IP module low circuits for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

13
  1. Reconnect all SIR components.
  2. Verify that all components, connectors and CPAs are properly mounted.
  3. Turn ON the ignition, with the engine OFF.
  4. Verify that DRIVER SENSELO and PASS. SENSELO are more than the specified value.

Does the scan tool indicate that DRIVER and/or PASSENGER SENSELO is greater than the specified value?

2.2 V

Go to Step 15

Go to Step 14

14

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

Did you complete the replacement?

--

Go to Step 15

--

15
  1. Use the scan tool in order to Clear the DTCs.
  2. 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