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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 134 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> DTC B0078: Passenger-Side Sis Circuit Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. If SIR Diagnostic System Check has been performed, go to next step. If SIR Diagnostic System Check has not been performed, go to SYSTEM OPERATION CHECK .
  2. Disconnect passenger-side SIS connector. See SIDE IMPACT SENSOR (SIS)  under REMOVAL & INSTALLATION. If connector is damaged or corroded, go to next step. If connector is okay, go to step  4.
  3. If SIS harness connector is damaged, replace connector. See WIRE REPAIR . Go to step  11. If SIS terminals are damaged, replace SIS. Go to step  18.
  4. Reconnect passenger-side SIS. Ensure Connector Position Assurance (CPA) clip is installed. Turn ignition on. Using scan tool, request SIR DTC's. If DTC B0078 is current, go to next step. If DTC B0078 is not current, go to DIAGNOSTIC AIDS .
  5. Disconnect SDM connector. See Figure. If SDM connector shows signs of corrosion, poor connections or other damage, go to step  16. If SDM connector is okay, go to next step.
    NOTE: Use Digital Multimeter (J-39200) and Connector Test Adapter Kit (J-35616-A) or Flat Wire Probe Adapter Kit (J-42675) when performing electrical tests.
  6. Disconnect passenger-side SIS connector. Measure resistance of Tan wire between SDM harness connector terminal B8 and passenger-side SIS connector terminal "B". See Figure & Figure . If low or no resistance is not indicated, go to next step. If low or no resistance is indicated, go to step  8.
  7. Repair open or high resistance in circuit 2163. See WIRE REPAIR . Go to step  18.
  8. Measure resistance of Dark Green wire between SDM harness connector terminal B7 and driver-side SIS connector terminal "A". See Figure & Figure . Press MIN MAX button on DMM. Connect leads of DMM to appropriate terminals. If low or no resistance is not indicated, go to next step. If low or no resistance is indicated, go to step  10.
  9. Repair open or high resistance in circuit 2164. See WIRE REPAIR . Go to step  18.
  10. Measure resistance between SDM terminals B7 and B8. If resistance is less than infinite, go to next step. If resistance is infinite, go to step  12.
  11. Repair short between circuits 2163 and 2164. See WIRE REPAIR . Go to step  18.
  12. Turn ignition on. Using Digital Multimeter (J-39200), measure voltage between SDM harness connector terminal B7 and ground. If voltage is one volt or more, go to next step. If voltage is less than one volt, go to step  14.
  13. Repair short to voltage in circuit 2164. See WIRE REPAIR . Go to step  18.
  14. Measure voltage between SDM harness connector terminal B8 and ground. If voltage is one volt or more, go to next step. If voltage is less than one volt, go to step  17.
  15. Repair short to voltage in circuit 2163. See WIRE REPAIR . Go to step  18.
  16. Replace SDM connector. See WIRE REPAIR . Go to step  18.
  17. Replace SIS. See SIDE IMPACT SENSOR (SIS)  under REMOVAL & INSTALLATION. Go to next step.
  18. Reconnect all SIR components. Ensure CPA clips are installed correctly. Turn ignition on. Using scan tool, clear all SIR DTC's. Road test vehicle. Recheck for SIR DTC's. If DTC B0078 is retrieved, go to next step. If DTC B0078 is not retrieved, system is normal.
  19. Replace SDM. See SENSING & DIAGNOSTIC MODULE (SDM)  under REMOVAL & INSTALLATION. Go to next step.
  20. Clear all SIR DTC's. Go to SIR DIAGNOSTIC SYSTEM CHECK .
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