GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Lumina 🢒 Restraints 🢒 SIR 🢒 DTC B1021 Driver Deployment Loop Resistance High

Object Number: 590601 Size: SF
SIR Component Views
Power, Ground, IP MIL, SDM, IP Module, Steering Wheel Coil, STeEring Wheel Module, Seat Belt Switch and Seat Belt/Ignition Key/Lamps Alarm
SIR Handling Caution
Handling ESD Sensitive Parts Notice

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. Next the SDM measures IGNITION 1 and the deployment loop voltages to make sure they are with their respective normal voltage ranges. Then the SDM proceeds with the resistance measurement test. During one portion for the resistance measurement test, the SDM does the following:

During one portion for the resistance measurement test, the SDM does the following:

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

Conditions for Running the DTC
    • The driver and passenger deployment loops are not open.
    • The driver and passenger deployment loop is not shorted to voltage.
    • The driver deployment loop is not shorted to ground.

Conditions for Setting the DTC

The driver deployment loop resistance is more than 3.8 ohms.

The resistance measurement test checks for this malfunction. This test only occurs once each ignition cycle when IGNITION 1 is within the normal operating voltage range.

Action Taken When the DTC Sets

The SDM commands ON the AIR BAG warning lamp.

Conditions for Clearing the DTC
    • The resistance of the driver deployment loop is less than 3.8 ohms and the ignition switch is cycled.
    • You can issue a CLEAR CODES command.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

A poor connection can cause and intermittent condition. Check the following for a poor connection:

    • The inflatable restraint steering wheel module coil yellow connector.
    • The upper inflatable restraint steering wheel module coil yellow connector.
    • The SDM wiring harness yellow connector.
    • The wire to terminal connections in the driver side high circuit.
    • The wire to terminal connections in the driver side low circuit.

The diagnostic table directs the technician to note the entry value of DRIVER RESISTANCE. Comparing the value of DRIVER RESISTANCE over multiple ignition cycles can be helpful in determining if an intermittent condition exists.

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 step checks the driver deployment loop resistance that was measured by the inflatable restraint sensing and diagnostic module (SDM).

    2.

  2. This step checks to see if the inflatable restraint steering wheel module yellow 2-way connector is corroded or damaged.

    3.

  3. This step isolates the malfunction to one side of the inflatable restraint steering wheel module yellow 2-way connector.

    4.

  4. This step determines if there is a malfunctioning inflatable restraint steering wheel module coil or if there is a malfunctioning inflatable restraint steering wheel module.

    5.

  5. This step checks the SDM wiring harness connector for corrosion or damaged terminals.

    6.

  6. This step checks to see if there is a high resistance in the driver side high circuit.

    7.

  7. This step determines if there is a high resistance in the driver side low circuit or if there is a malfunctioning SDM.

DTC B1021 Driver Deployment Loop Resistance High

Step

Action

Value(s)

Yes

No

1

Did you perform the SIR Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Install the scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool to request the SIR scan tool data list.
  5. Read and record on the repair order the driver deployment loop resistance DRIVER RESISTANCE.

Has the DRIVER RESISTANCE been read and recorded on the repair order?

--

Go to Step 3

--

3

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  3. Check for a proper connection of the driver side high circuit and the driver side low circuit on the IP wiring harness side of the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.

Are the terminals damaged or corroded?

--

Go to Step 4

Go to Step 6

4

Replace the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 5

--

5

Check for a proper connection of the driver side high circuit and the driver side low circuit at the inflatable restraint steering wheel module coil yellow 2-way connector.

Are the terminals damaged or corroded?

--

Go to Step 7

Go to Step 23

6

Check for a proper connection of the driver side high circuit and the driver side low circuit at the inflatable restraint steering wheel module coil yellow 2-way connector.

Are the terminals damaged or corroded?

--

Go to Step 7

Go to Step 8

7

Replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you compete the repair?

--

Go to Step 23

--

8
  1. Connect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool to request the SIR scan tool data list.
  4. Read the driver deployment loop resistance DRIVER RESISTANCE.

Is DRIVER RESISTANCE more than the specified value?

3.8 ohms

Go to Step 10

Go to Step 9

9
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 23

--

10

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint steering wheel module coil and IP module yellow 2-way wiring harness connectors.
  3. Install the J 38715-A SIR Driver/Passenger Load Tool PASSENGER INFLATOR connector to inline connector C216 and BASE OF COLUMN connector to inline connector C215.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request the SIR scan tool data list.
  6. Read the driver deployment loop resistance DRIVER RESISTANCE.

Is DRIVER RESISTANCE more than the specified value?

3.8 ohms

Go to Step 14

Go to Step 11

11

  1. Turn OFF the ignition.
  2. Remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  3. Disconnect the J 38715-A from the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.
  4. Connect the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.
  5. Use the J-38715-30A adapter to connect the J 38715-A SIR Driver/Passenger Load Tool STEERING COLUMN connector to the inflatable restraint steering wheel module coil integral connector.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request the SIR scan tool data list.
  8. Read the driver deployment loop resistance DRIVER RESISTANCE.

Is DRIVER RESISTANCE more than the specified value?

3.8 ohms

Go to Step 13

Go to Step 12

12
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Did you complete the repair?

--

Go to Step 23

--

13
  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 repair?

--

Go to Step 23

--

14

  1. Turn OFF he ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Remove the J 38715-A .
  4. Check for a proper connection of the driver side high circuit and the driver side low circuit at the SDM wiring harness connector.

Is the SDM wiring harness connector damaged or corroded?

--

Go to Step 15

Go to Step 17

15

Replace the SDM wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

16

Check for a proper connection of the driver side high circuit and the driver side low circuit at the SDM.

Are the SDM terminals damaged or corroded?

--

Go to Step 18

Go to Step 23

17

Check for a proper connection of the driver side high circuit and the driver side low circuit at the SDM.

Are the SDM terminals damaged or corroded?

--

Go to Step 18

Go to Step 19

18

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

Did you complete the repair?

--

Go to Step 23

--

19

  1. Zero the J 39200 Digital Multimeter (DMM).
  2. Use the J 39200 to measure the resistance of the driver side high circuit between the SDM wiring harness connector and the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.

Is the measured resistance within the specified value?

0-0.5 ohms

Go to Step 21

Go to Step 20

20
  1. Locate a high resistance in the driver side high circuit.
  2. Repair the high resistance in the driver side high circuit.

Did you complete the repair?

--

Go to Step 23

--

21

Use the J 39200 to measure the resistance of the driver side low circuit between the SDM wiring harness connector and the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.

Is the measured resistance within the specified value?

0-0.5 ohms

Go to Step 18

Go to Step 22

22
  1. Locate a high resistance in the driver side low circuit.
  2. Repair the high resistance in the driver side low circuit.

Did you complete the repair?

--

Go to Step 23

--

23
  1. Reconnect all SIR components.
  2. Verify that all components and connectors are properly mounted.
  3. Turn ON the ignition, with the engine OFF.
  4. Use the scan tool in order to clear the DTCs.

Did you complete the action?

--

Go to Diagnostic System Check - SIR

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