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Home >> Chevrolet >> 2008 >> Impala SS >> Repair and Diagnosis >> External Pages >> Different car >> Section 1211 (Supplemental Inflatable Restraint System) >> Diagnostic Information and Procedures >> DTC B0021 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Refer to SIR Service Precautions .
When removing the connectors, inspect for terminal damage or corrosion. Inspect the connector body for damage to the locators that disengage the shorting bars when connected. Damage or corrosion to the following components requires repair or replacement of the affected component/connector:
  • Inflatable restraint module
  • SDM module
  • Front end sensor wiring harness connector
  • SDM wiring harness connector

The connector and connector position assurance (CPA) may seat independent of each other. Both the connector and CPA should seat with an audible and/or tactile click. Correct connection isolates the shorting-bars within the connector allowing the deployment circuit to operate properly.
  1. Verify that the inflatable restraint RF side impact module connector and CPA are engaged.
    • If the above condition is not found, make the appropriate repair.
  2. Ignition OFF, disconnect the harness connector at the RF side impact module.
  3. Install a 3 A fused jumper between the J 38715-A  or SA9409Z-A  and the harness connector of the RF side impact module. See Special Tools .
  4. Ignition ON, with a scan tool, verify that DTC B0021 is set as current.
    • If the DTC is not set or is set as history, cycle the ignition OFF, disconnect the 3A fused jumper, reconnect the harness connector at the RF side impact module, and cycle the ignition ON. If the DTC resets after reconnecting the module, replace the RF side impact module.
  5. Ignition OFF, disconnect the 3 A fused jumper.
  6. Disconnect the harness connector at the SDM.
  7. Ignition ON, test for less than 1.0 V between the appropriate control circuit listed below and ground:
    • Control circuit terminal 20
    • Control circuit terminal 21
    • If not within the specified range, test the control circuit for a short to voltage.
  8. Ignition OFF, test for infinite resistance between the appropriate control circuit listed below and ground:
    • Control circuit terminal 20
    • Control circuit terminal 21
    • If not within the specified value, test the control circuit for a short to ground.
  9. Test for less than 1 Ω between the appropriate control circuit terminal and SDM terminal listed below:
    • Control circuit terminal 1 and SDM terminal 21
    • Control circuit terminal 2 and SDM terminal 20
    • If not within the specified range, test the control circuit for an open/high resistance.
  10. If all circuits test normal, replace the SDM.
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