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ONSTAR(R) Diagnostic System Check

NOTE: Vehicle Interface Unit (VIU) may be used as the interface unit between ONSTAR(R) system and Radio Interface Module (RIM). Manufacturer information not available.
  1. Ensure battery condition, cold cranking amperage and reserve capacity meet specifications. Replace as necessary. Install scan tool to Data Link Connector (DLC). If scan tool powers up, go to next step. If scan tool does not power up, go to SCAN TOOL DOES NOT POWER UP  .
  2. Turn ignition on, engine off. Try to establish scan tool communication with Vehicle Interface Unit (VIU). If communication with VIU is established, go to next step. If communication with VIU is not established, go to DTC U1000 & DTC U1255: CLASS 2 COMMUNICATION MALFUNCTION  .
  3. Select display DTC function for VIU. Record all displayed DTCs and status of displayed DTCs. If DTCs are displayed, go to next step. If no DTCs are displayed, attempt to diagnose system by symptom. Go to SYMPTOM TESTS  .
  4. If scan tool displays any DTCs that begin with "U", go to next step. If scan tool does not display any DTCs that begin with "U", go to step  6 .
  5. If scan tool displays DTC U1500, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform appropriate test. If scan tool does not display DTC U1500, go to DTC U1000 & DTC U1255: CLASS 2 COMMUNICATION MALFUNCTION  .
  6. If scan tool displays DTC B1000, B1004, B1007 or B1009, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform appropriate test. If scan tool does not display DTC B1000, B1004, B1007 or B1009, go to next step.
  7. If scan tool displays DTC B1327 or B1328, go to BODY CONTROL MODULE (BCM) DTC DEFINITIONS  table and perform appropriate test. If scan tool does not display DTC B1327 or B1328, perform symptom diagnosis on ONSTAR(R) system.
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