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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Restraints 🢒 SIR 🢒 DTC B1121 Driver Deployment Loop Resistance High

Object Number: 585655 Size: MF
SIR Components
SIR Schematics
SIR Handling Caution
Handling ESD Sensitive Parts Notice
SIR Schematic Icons

Circuit Description

When you first turn ON the ignition, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM proceeds with the resistance measurement test. During one portion of the resistance measurement test, the SDM does the following:

    • Grounds the driver frontal low terminal through an internal current sink.
    • Connects the driver frontal high terminal to an internal constant current source. This current produces proportional voltage drops in the deployment loop.
    • Measures the voltage difference between driver frontal high and low circuits.
    • Calculates the resistance of the driver frontal deployment loop using the measured voltage.

Conditions for Running the DTC
    • Ignition 1 voltage is within the normal operating voltage range.
    • Driver frontal deployment loop is not open.
    • Driver frontal deployment loop is not shorted to voltage.
    • Driver frontal deployment loop is not shorted to ground.

Conditions for Setting the DTC

Driver frontal deployment loop resistance is greater than 3.8 ohms for 500 milliseconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC
    • The resistance of the driver frontal deployment loop is less than or equal to 3.8 ohms for 500 milliseconds.
    • You can issue a CLEAR CODES command
    • A history DTC will clear once 250 malfunction free ignition cycles have occurred

When you issue a scan tool CLEAR CODES command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the driver frontal high and the driver frontal low circuits.
    • A malfunctioning shorting bar on the inflatable restraint driver inflator module connector.
    • A malfunctioning shorting bar on the inflatable restraint steering wheel module coil connector.

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

Test Description

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

  1. This step checks the in-line connector below the steering wheel restraint module coil.

    2.

  2. This step test for the proper operation of inflatable restraint steering wheel module coil and/or inflatable restraint steering wheel inflator module.

    3.

  3. This step determines if there is high resistance driver frontal high circuit.

    4.

  4. This step determines if there is high resistance driver frontal low circuit, or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Disconnect the in-line connector that connect steering wheel restraint module coil to vehicle wiring harness.
  3. Inspect both wiring harness connectors for the following conditions:
    4. • Corrosion
    • Terminal damaged
    • Poor connections/terminal tension
  4. If any of the above conditions are found refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Does connector exhibits any signs of corrosion, terminal damaged, or poor connections?

--

Go to Step 3

Go to Step 4

3
  1. Replace the wiring harness side of in-line connector. Refer to Connector Repairs in Wiring Systems.
  2. If steering wheel restraint module coil exhibits any of the above conditions, the module must be replace. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

--

Go to Step 14

--

4
  1. Reconnect the in-line connector.
  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 is current?

--

Go to Step 5

Go to Diagnostic Aids

5
  1. Turn OFF the ignition.
  2. Disconnect the in-line connector below the steering wheel restraint module coil.
  3. Install the J 38715-A SIR Load Tool to vehicle wiring harness in-line connector. Use the appropriate wiring harness connector adaptors where necessary.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC is current?

--

Go to Step 9

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Remove the inflatable restraint steering wheel inflator module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Disconnect the J 38715-A from the in-line connector.
  4. Reconnect the in-line connector back together.
  5. Install the J 38715-A to the upper inflatable restraint steering wheel module coil connector on the steering column.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC is current?

--

Go to Step 8

Go to Step 7

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

Did you complete the replacement?

--

Go to Step 14

--

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

Did you complete the replacement?

--

Go to Step 14

--

9

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Disconnect the J 38715-A .
  4. Use the J 39200 DMM and measure the resistance of driver frontal high circuit between the SDM harness connector and inflatable restraint steering wheel yellow connector.

Does the resistance measure greater than the specified value?

0-0.5 ohms

Go to Step 10

Go to Step 11

10

Locate and repair high resistance in the driver frontal high circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

11

Use the J 39200 and measure the resistance of driver frontal low circuit between the SDM harness connector and inflatable restraint steering wheel yellow connector.

Does the resistance measure greater than the specified value?

0-0.5 ohms

Go to Step 12

Go to Step 13

12

Locate and repair high resistance in the driver frontal low circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

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13

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

Did you complete the replacement?

--

Go to Step 14

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14
  1. Reconnect all SIR components.
  2. Verify that all components and connectors 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.

Did you complete the action?

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Go to Diagnostic System Check - SIR

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