GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Impala 🢒 Restraints 🢒 SIR 🢒 DTC B0077 LF/Driver SIS Malfunction

Object Number: 490873 Size: SF
SIR Components
Power, Ground, Side Impact Sensor, and Frontal Air Bags
Handling ESD Sensitive Parts Notice
SIR Caution

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. The SDM provides input power to the inflatable restraint side impact sensor (SIS). When input power is first detected, the SIS responds by performing internal diagnostics. Next the SIS sends an ID message to the SDM. The SDM will consider this to be a valid ID if the response time is less than 5 seconds after the SIS is powered up.The SIS will continually communicate a status message to the SDM. The SDM can reset the SIS by removing and applying power to it.

Conditions for Running the DTC
    • Ignition 1 voltage is within the normal operating voltage range.
    • The SDM monitors the inflatable restraint side impact sensor loop with the ignition ON.

Conditions for Setting the DTC

The SDM has detected one of the following conditions due to a fault in the SIS interface circuit:

    • A valid ID message is not received within 5 seconds of the SIS being powered up.
    • Status message is not received.
    • The SDM has failed twice to reset the SIS.

Action Taken When the DTC Sets
    • The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
    • The SDM attempts to reset the SIS.

Conditions for Clearing the DTC
    • Current DTC
       - The SDM has detected correct operation.
       - The SIS sends an OK message to the SDM.
    • History DTC
       - You issue a scan tool CLEAR CODES command.
       - Once 255 malfunctions free ignition cycles have occurred.

Diagnostic Aids

An inflatable restraint side impact sensor (SIS) circuit open, high resistance, low resistance, short to ground, or short to voltage can cause an intermittent condition. Inspect the inflatable restraint side impact sensor high and sensor low circuits carefully for cutting and/or chafing.

Test Description

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

  1. This step checks the inflatable restraint side impact sensor wiring harness connector for corrosion or damaged terminals.

    2.

  2. This step checks the inflatable restraint side impact sensor for corrosion or damaged terminals.

    3.

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

    4.

  4. This step checks to see if there is an open or a high resistance in the inflatable restraint side impact sensor high circuit.

    5.

  5. This step checks to see if there is an open or a high resistance in inflatable restraint side impact sensor low circuit.

    6.

  6. This step checks to see if there is a short between the inflatable restraint side impact sensor high circuit and the inflatable restraint side impact sensor low circuit.

    7.

  7. This step checks to see if there is a short to ground in the inflatable restraint side impact sensor high circuit.

    8.

  8. This step checks to see if there is a short to ground in the inflatable restraint side impact sensor low circuit.

    9.

  9. This step checks to see if there is a short to voltage in the inflatable restraint side impact sensor high circuit.

    10.

  10. This step checks to see if there is a short to voltage in the inflatable restraint side impact sensor low circuit.

    11.

  11. This step determines if the problem was solved by replacing the inflatable restraint side impact sensor (SIS) or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform A Diagnostic System Check - SIR?

--

Go to Step 2

Go to cell-id="57882">A Diagnostic System Check - SIR>

2

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint side impact sensor (SIS) 2-way connector. Refer to cell-id="57813">Inflatable Restraint Side Impact Sensor Replacement> .
  3. Inspect the SIS wiring harness connector for the following conditions:
    4. • Corrosion
    • Damaged terminals
    • Poor connections/terminal tension

Does the SIS wiring harness connector exhibit any signs of corrosion, terminal damage, or poor connections?

--

Go to Step 3

Go to Step 5

3

Replace the SIS wiring harness connector. Refer to cell-id="61973">Connector Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 4

--

4

Inspect the SIS terminals for corrosion or damaged terminals.

Does the SIS terminals exhibit any signs of corrosion or damaged terminals?

--

Go to Step 6

Go to Step 29

5

Inspect the SIS terminals for corrosion or damaged terminals.

Does the SIS terminals exhibit any signs of corrosion or damaged terminals?

--

Go to Step 6

Go to Step 7

6

Replace the SIS. Refer to cell-id="57813">Inflatable Restraint Side Impact Sensor Replacement> .

Did you complete the replacement?

--

Go to Step 29

--

7

  1. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> or cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> .
  2. Inspect the SDM wiring harness connector for the following conditions:
    3. • Corrosion
    • Damaged terminals
    • Poor connections/terminal tension

Does the SDM wiring harness connector exhibit any signs of corrosion, damaged terminals, or poor connections?

--

Go to Step 8

Go to Step 10

8

Replace the SDM wiring harness connector. Refer to cell-id="61973">Connector Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 9

--

9

Inspect the SDM terminals for corrosion or damaged terminals.

Does the SDM exhibit any signs of corrosion or damaged terminals?

--

Go to Step 11

Go to Step 29

10

Inspect the SDM terminals for corrosion or damaged terminals.

Does the SDM exhibit any signs of corrosion or damaged terminals?

--

Go to Step 11

Go to Step 12

11

Replace the SDM. Refer to cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> or cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> .

Did you complete the replacement?

--

Go to Step 29

--

12

  1. Zero the J 39200 Digital Multimeter (DMM).
  2. Use the DMM to measure the resistance of the inflatable restraint side impact sensor high circuit.

Does the resistance measure less than the specified value?

0.5 ohms

Go to Step 14

Go to Step 13

13

Locate and repair an open or a high resistance in the inflatable restraint side impact sensor high circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

14

Use the DMM to measure the resistance of the inflatable restraint side impact sensor low circuit.

Does the resistance measure less than the specified value?

0.5 ohms

Go to Step 16

Go to Step 15

15

Locate and repair an open or a high resistance in the inflatable restraint side impact sensor low circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

16

Use the DMM to measure the resistance between the inflatable restraint side impact sensor high and low circuits

Does the resistance measure less than the specified value?

OL

Go to Step 17

Go to Step 18

17

Locate and repair a short between the inflatable restraint side impact sensor high and low circuits. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

18

Use the DMM to measure the resistance between the inflatable restraint side impact sensor high circuit and a known good ground.

Does the resistance measure less than the specified value?

OL

Go to Step 19

Go to Step 20

19

Locate and repair a short to ground in the inflatable restraint side impact sensor high circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

20

Use the DMM to measure the resistance between the inflatable restraint side impact sensor low circuit and a known good ground.

Does the resistance measure less than the specified value?

OL

Go to Step 21

Go to Step 22

21

Locate and repair a short to ground in the inflatable restraint side impact sensor low circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

22

  1. Turn ON the ignition, with the engine OFF.
  2. Use the DMM to measure the voltage between the inflatable restraint side impact sensor high circuit and a known good ground.

Does the voltage measure less than the specified value?

1 V

Go to Step 24

Go to Step 23

23

Locate and repair a short to B+ in the inflatable restraint side impact sensor high circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

24

Use the DMM to measure the voltage between the inflatable restraint side impact sensor low circuit and a known good ground.

Does the voltage measure less than the specified value?

1 V

Go to Step 26

Go to Step 25

25

Locate and repair a short to B+ in the inflatable restraint side impact sensor low circuit. Refer to cell-id="62194">Circuit Testing> and cell-id="61965">Wiring Repairs> in Wiring Systems.

Did you complete the repair?

--

Go to Step 29

--

26
  1. Turn OFF the ignition.
  2. Replace the inflatable restraint side impact sensor. Refer to cell-id="57813">Inflatable Restraint Side Impact Sensor Replacement> .

Did you complete the replacement?

--

Go to Step 27

--

27

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool to request the SIR DTC display.

Does the scan tool indicate that this DTC is current?

--

Go to Step 28

Go to Step 29

28

Replace the SDM. Refer to cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> or cell-id="57768">Inflatable Restraint Sensing and Diagnostic Module Replacement> .

Did you complete the replacement?

--

Go to Step 29

--

29
  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 repair?

--

Go to cell-id="57882">A Diagnostic System Check - SIR>

--