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Scan Tool Does Not Communicate With Components

CAUTION: Body Function Controller (BFC) Pink 24-pin connector C3 contains power and ground sources. When removing BFC, always disconnect connector C3 first before disconnecting connectors C1 and C2. When installing BFC, always reconnect connectors C1 and C2, then connector C3 last.
  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - GASOLINE - EXCEPT METRO, PRIZM & TRACKER article in ENGINE PERFORMANCE. Go to next step.
  2. Observe operation of Malfunction Indicator Light (MIL). Turn ignition switch to RUN position. If MIL comes on, go to next step. If MIL does not come on, diagnose MIL. See MIL DIAGNOSIS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - GASOLINE - EXCEPT METRO, PRIZM & TRACKER article in ENGINE PERFORMANCE.
  3. Connect 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 INOPERATIVE  .
  4. Attempt to establish communications with Body Function Controller (BFC), Electronic Brake Control Module (EBCM) and Powertrain Control Module (PCM). If scan tool communicates with control modules, go to step  7 . If scan tool does not communicate with control modules, go to next step.
  5. Disconnect BFC connectors. Attempt to communicate with EBCM and PCM. If scan tool communicates with control modules, go to step  10 . If scan tool does not communicate with control modules, go to next step.
  6. Check for open or short to ground in Purple wire between left instrument panel junction block, PCM and EBCM. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK  . If circuit is okay, go to next step.
  7. Reconnect control module connectors. Check for open or short to ground in Purple wire between left instrument panel junction block and DLC. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK  . If circuit is okay, go to next step.
  8. Check for intermittent conditions. Wiggle wiring harness and connectors to control modules. Repair as necessary. If circuits and connectors are okay, go to next step.
  9. Replace left instrument panel junction block. After repairs, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK  .
  10. Check for open or short to ground in Purple wire between left instrument panel junction block and BFC. See appropriate wiring diagram in DATA LINK CONNECTORS article in WIRING DIAGRAMS. If faulty circuit is found and repaired, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK  . If circuit is okay, go to next step.
  11. Replace BFC. See BODY FUNCTION CONTROLLER (BFC)  under REMOVAL & INSTALLATION. After repairs, go to DATA LINK COMMUNICATIONS DIAGNOSTIC SYSTEM CHECK  .
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