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Home >> Chevrolet >> 1998 >> Monte Carlo LS >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Engine Controls - Tests W/Codes - 3.8L) >> Diagnostic Trouble Codes >> DTC P1605 - HVAC Serial Data Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Using scan tool, attempt to select HVAC data. If HVAC data can be displayed, go to next step. If HVAC cannot be displayed, go to step 4).
  3. Turn ignition off. Disconnect HVAC controller and PCM harness connector. Check serial data circuit for open between HVAC controller and PCM. Repair as necessary. After repairs, go to step 6). If circuit is okay, go to next step.
  4. Check serial data circuit for poor connection at HVAC controller. Repair as necessary. After repairs, go to step 6). If circuit is okay, go to next step.
  5. Check serial data circuit for poor connection at PCM. Repair as necessary. After repairs, go to next step. If connection is okay, diagnose A/C-heater system. See A/C-HEATER SYSTEM article.
  6. Review and record scan tool FAIL RECORDS data. Clear DTC(s). Operate vehicle within the FAIL RECORDS conditions. Using scan tool, monitor SPECIFIC DTC INFO for DTC P1605. If scan tool indicates that DTC P1605 failed, repeat step 2). If scan tool does not indicate that DTC P1605 failed, system is okay.
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