GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon XL - 2WD 🢒 DTC 🢒 DTC B0078 RF/Passenger SIS Malfunction

Object Number: 612822 Size: SF
SIR Components
SIR Schematics Utilities
SIR Caution
Handling ESD Sensitive Parts Notice

Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM provides input power to the side impact sensor (SIS). When input power is first detected, the SIS responds by performing internal diagnostics. The SIS then 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 is capable of resetting the SIS by removing and applying power to it.

Conditions for Running the DTC
    • Ignition 1 voltage is within the normal operating voltage range.
    • RF SIS loop is not shorted to voltage.
    • RF SIS loop is not shorted to ground.

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

Conditions for Clearing the DTC
    • The SDM has detected correct operation.
    • The SDM recieves an OK message from the RF SIS.
    • You issue a scan tool CLEAR CODES command.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the RF inflatable restraint side impact sensor (SIS) passenger sensor high and passenger sensor low circuits.
    • High or low resistance in the RF inflatable restraint side impact sensor (SIS) passenger sensor high and passenger sensor low circuits.
    • Inspect the RF inflatable restraint side impact sensor (SIS) passenger sensor high and passenger sensor low circuits carefully for cutting and/or chafing.
    • 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 inspects the inflatable restraint side impact sensor (SIS) wiring harness connector.

    2.

  2. This step inspects the inflatable restraint side impact sensor (SIS) connector terminals.

    3.

  3. This step inspects the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector.

    4.

  4. Tests for an open or high resistance in the inflatable restraint side impact sensor (SIS) passenger sensor low circuit.

    5.

  5. Tests for an open or high resistance in the inflatable restraint side impact sensor (SIS) passenger sensor high circuit.

    6.

  6. Tests for a short between the inflatable restraint side impact sensor (SIS) passenger sensor high and passenger sensor low circuits.

    7.

  7. Tests for a short to ground in the inflatable restraint side impact sensor (SIS) passenger sensor high circuit.

    8.

  8. Tests for a short to ground in the inflatable restraint side impact sensor (SIS) passenger sensor low circuit.

    9.

  9. Tests for a short to voltage in the inflatable restraint side impact sensor (SIS) passenger sensor high circuit.

    10.

  10. Tests for a short to voltage in the inflatable restraint side impact sensor (SIS) passenger sensor low circuit.

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. Disconnect the RF inflatable restraint side impact sensor (SIS) harness connector. Refer to Inflatable Restraint Side Impact Sensor Replacement .
  3. Inspect the inflatable restraint side impact sensor (SIS) wiring harness connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

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

--

Go to Step 3

Go to Step 4

3

Repair or replace the inflatable restraint side impact sensor (SIS) harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 24

--

4

Check for proper connection at the RF side impact sensor (SIS) connector terminals.

Do the terminals exhibit any signs of damage or corrosion?

--

Go to Step 23

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

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

--

Go to Step 6

Go to Step 7

6

Repair or replace the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 24

--

7

Check for proper connection at the inflatable restraint sensing and diagnostic module (SDM) connector terminals.

Do the terminals exhibit any signs of damage or corrosion?

--

Go to Step 22

Go to Step 8

8

UsingJ 39200 DMM measure the resistance of the RF inflatable restraint side impact sensor (SIS) passenger sensor low circuit. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

0.5 ohms

Go to Step 10

Go to Step 9

9

Locate and repair an open or high resistance in the side impact sensor (SIS) passenger sensor low circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

10

UsingJ 39200 DMM measure the resistance of the RF inflatable restraint side impact sensor (SIS) passenger sensor high circuit. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

0.5 ohms

Go to Step 12

Go to Step 11

11

Locate and repair an open or high resistance in the side impact sensor (SIS) passenger sensor high circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

12

UsingJ 39200 DMM measure the resistance between the RF inflatable restraint side impact sensor (SIS) passenger sensor high and passenger sensor low circuits. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 13

Go to Step 14

13

Locate and repair a short between the side impact sensor (SIS) passenger sensor high and passenger sensor low circuits. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

14

UsingJ 39200 DMM measure the resistance between the RF inflatable restraint side impact sensor (SIS) passenger sensor high circuit and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 15

Go to Step 16

15

Locate and repair a short to ground in the side impact sensor (SIS) passenger sensor high circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

16

UsingJ 39200 DMM measure the resistance between the RF inflatable restraint side impact sensor (SIS) passenger sensor low circuit and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure less than the specified value?

OL

Go to Step 17

Go to Step 18

17

Locate and repair a short to ground in the side impact sensor (SIS) passenger sensor low circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

18

  1. Turn ON the ignition, with the engine OFF.
  2. UsingJ 39200 DMM measure the voltage between the RF inflatable restraint side impact sensor (SIS) passenger sensor high circuit and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure less than the specified value?

1 V

Go to Step 20

Go to Step 19

19

Locate and repair a short to voltage in the side impact sensor (SIS) passenger sensor high circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

20

UsingJ 39200 DMM measure the voltage between the RF inflatable restraint side impact sensor (SIS) passenger sensor low circuit and a known good ground. Refer to Circuit Testing in Wiring Systems.

Does the voltage measure less than the specified value?

1 V

Go to Step 23

Go to Step 21

21

Locate and repair a short to voltage in the side impact sensor (SIS) passenger sensor low circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

--

22

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

Did you complete the replacement?

--

Go to Step 24

--

23

Replace the RF inflatable restraint side impact sensor (SIS). Refer to Inflatable Restraint Side Impact Sensor Replacement .

Did you complete the replacement?

--

Go to Step 24

--

24
  1. Reconnect all SIR system components.
  2. Verify that all components, connectors, and CPAs 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.

Does the DTC reset?

--

Go to Step 2

System OK