Circuit Description
The inflatable restraint side impact sensor (SIS) is equipped on Silverado and Sierra models with RPO code HP2 only. The single SIS is located on the right side of the vehicle in the passenger door. The SIS utilizes a unidirectional 2-wire circuit and modulates current on the interface to send ID, State of Health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). The SDM serves as a power source and a ground for the SIS. When the ignition is turned ON and input power from the SDM is first detected, the SIS responds by performing internal diagnostics and sending an ID to the SDM. The SDM considers the ID to be valid if the response time is less than 5 seconds. The SIS continually communicates status messages to the SDM, which determines if a fault is present in the SIS circuit. When a fault is detected, the SDM resets the SIS twice by removing and reapplying power. If the fault is still present, the SDM will set a diagnostic trouble code (DTC).
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC B0078 Right Front/Passenger Side Impact Sensor (SIS) Performance |
| • | DTC B0081 Incorrect Right Front/Passenger Side Impact Sensor (SIS) Installed |
| • | DTC B0082 Discard Right Front/Passenger Side Impact Sensor (SIS) |
Conditions for Running the DTC
Ignition 1 voltage is within the normal operating voltage range.
Conditions for Setting the DTC
| • | DTC B0078 will set when one of the following conditions occur: |
| - | 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. |
| • | DTC B0081 will set when one of the following conditions occur: |
| - | The SDM has received an ID message from the SIS which does not match the ID stored in the SDM memory. |
| - | When two SIS resets are attempted without the correct identification being detected by the SDM. |
| • | DTC B0082 will set when the SDM has received a NOK (Not OK) message from the SIS. |
Action Taken When the DTC Sets
| • | The SDM commands the AIR BAG indicator ON via class 2 serial data. |
| • | The SDM attempts to reset the SIS. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | You issue a scan tool CLEAR DTCs command. |
| • | A history DTC will clear once 255 malfunction-free ignition cycles have occurred. |
Diagnostic Aids
The following can cause an intermittent condition:
| • | A short between the SIS signal and voltage circuits |
| • | High or low resistance in the SIS signal and voltage circuits |
| • | Inspect the SIS signal and voltage circuits carefully for cutting and/or chafing |
| • | Verify that the correct SIS is installed in the vehicle |
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:
-
Tests the communication status of the SIS.
-
Tests for a short to ground, a high resistance, or an open in the SIS signal circuit.
-
Tests for a short to ground, a high resistance, or an open in the SIS voltage circuit.
-
Tests for a short to voltage in the SIS signal and voltage circuits.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the scan tool indicate that either DTC B0081, or B0082 is current? | Go to Step 12 | Go to Step 3 | |
3 |
Does the SIS terminals or harness connector exhibit any signs of damage or corrosion? | Go to Step 4 | Go to Step 5 |
4 |
Did you complete the replacement? | Go to Step 13 | -- |
5 |
Did you find and correct the condition? | Go to Step 13 | Go to Step 6 |
Test the right SIS signal circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 7 | |
Test the right SIS voltage circuit for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 8 | |
Did you find and correct the condition? | Go to Step 13 | Go to Step 9 | |
9 | Replace the right SIS. Refer to Inflatable Restraint Side Impact Sensor Replacement . Did you complete the replacement? | Go to Step 10 | -- |
10 |
Does the DTC reset? | Go to Step 11 | System OK |
11 | Replace the SDM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming . Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the right SIS. Refer to Inflatable Restraint Side Impact Sensor Replacement . Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
