LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Saturn >> 2000 >> LS1 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1640: Output Driver Module 1 >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Turn A/C switch off. Ensure A/C-heater mode selector is not in defrost mode. Start engine. Using scan tool, command A/C relay on and off. If A/C turns on and off, go to next step. If A/C is stuck on, check for short to ground in circuit between PCM harness connector J2 terminal 55 (Dark Green/White wire) and underhood fuse relay block. See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
  3. Turn ignition on, with engine off. Using scan tool, monitor A/C relay circuit for open/short to ground. If scan tool feedback reads YES, go to next step. If scan tool feedback does not read YES, problem is intermittent. See DIAGNOSTIC AIDS .
  4. Remove A/C relay located in underhood fuse/relay block. Using a test light connected to ground, probe A/C relay coil ignition feed terminal at fuse/relay block. See WIRING DIAGRAMS article. If test light illuminates, go to step  6. If test light does not illuminate, go to next step.
  5. Check IGN 3 fuse located in underhood fuse/relay block. If fuse is okay, replace fuse/relay block. If fuse is blown, repair short to ground in circuit or shorted component in fuse circuit. Repair or replace as necessary.
  6. Connect test light between fuse block connector terminal C4 (Dark Green/White wire) and A/C relay coil ignition feed circuit in fuse/relay block. Observe scan tool. If scan tool feedback changes to NO, replace A/C relay. If scan tool feedback does not change to NO, check for open in Dark Green/White wire circuit between fuse/relay block and PCM or for terminal tightness at connectors. Repair as necessary. If circuit or connectors are okay, replace PCM.
  7. Start engine. Using scan tool, command "EVAP System Perf" on. Monitor fuel tank pressure (voltage). If scan tool reading increase to greater than 2 volts, go to next step. If scan tool reading does not increase to greater than 2 volts, go to step  11.
  8. Command "EVAP System Perf" off. If fuel tank pressure returns to zero Hg, problem is intermittent. See DIAGNOSTIC AIDS . If fuel tank pressure does not return to zero Hg, go to next step.
  9. Turn ignition on, with engine off. Disconnect in-line EVAP vent solenoid 2-pin harness connector (located on rear of tank, behind heat shield). Connect a test light between 2-pin harness connector terminals "A" (Orange wire) and "B" (White wire). If test light does not illuminate, go to next step. If test light illuminates, check for short to ground in circuit (White wire) between connector and PCM. See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
  10. Repair short to ground in circuit (White wire) between connector and EVAP vent solenoid. Repair as necessary.
  11. Turn ignition on, with engine off. Disconnect in-line fuel tank 2-pin harness connector (located on rear of tank, behind heat shield). Connect a test light between ground and 2-pin harness connector terminal "A" (Orange wire). If test light does not illuminate, go to next step. If test light illuminates, check for open/short in EVAP vent solenoid circuits (White wire and Orange wire). See WIRING DIAGRAMS article. Repair as necessary.
  12. Connect test light between EVAP vent solenoid harness connector terminals "A" (Orange wire) and "B" (White wire). Using scan tool, command EVAP vent solenoid on and off. If test light illuminates, go to next step. If test light does not illuminate, check for open in White wire circuit or for terminal tightness at connector. Repair as necessary. If circuit or terminals are okay, replace PCM.
  13. Check for open between PCM and EVAP vent solenoid harness connectors "A" (Orange wire) or "B" (White wire). Repair as necessary. If circuit(s) are okay, check for terminal tightness at connectors. Repair as necessary. If terminals are okay, replace EVAP vent solenoid.
  14. Start engine. Using scan tool, command "EVAP System Seal" on. Hold engine speed at 2000 RPM. Using scan tool, monitor fuel tank pressure (voltage). If scan tool reading does not increase to greater than 2 volts, go to next step. If scan tool reading increases to greater than 2 volts, check for short to ground in EVAP purge solenoid circuit (Dark Green/White wire) to PCM. See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
  15. Command "EVAP System Perf" on. If scan tool does not reading increase to greater than 2 volts, go to next step. If scan tool reading increases to greater than 2 volts, problem is intermittent. See DIAGNOSTIC AIDS .
  16. Turn ignition on, with engine off. Disconnect EVAP purge solenoid harness connector (located on rear of air cleaner box). Connect a test light between ground and EVAP purge solenoid harness connector "A" (Red wire). If test light illuminates, go to next step. If test light does not illuminate, repair circuit for open or short to ground.
  17. Connect test light between EVAP purge solenoid harness connector terminals "A" (Red wire) and "B" (Dark Green/White wire). Using scan tool, command purge solenoid on. If test light illuminates, check for terminal tightness at connectors. If terminals are okay, replace EVAP purge solenoid. If test light does not illuminate, check for open in Dark Green/White wire between purge solenoid and PCM. Repair as necessary. If circuit is okay, check for terminal tightness at connector. Repair as necessary. If terminals are okay, replace PCM.
  18. Start engine. Using scan tool, command A/C relay on. If A/C compressor turns on, problem is intermittent. See DIAGNOSTIC AIDS . If A/C compressor does not turn on, go to next step.
  19. Command A/C relay off. Remove A/C relay from underhood fuse/relay block. Replace A/C relay with horn relay. Command A/C on. If A/C compressor turn on, replace A/C relay. If A/C compressor does not turn on, check for shorted circuit between A/C relay to PCM harness connector J2 terminal No. 55 (Dark Green/White wire). See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
  20. Turn ignition on, with engine off. Using scan tool, command EVAP vent on. Monitor EVAP vent circuit for short to voltage. If scan tool feedback reads YES, go to next step. If scan tool feedback does not read YES, problem is intermittent. See DIAGNOSTIC AIDS .
  21. Disconnect EVAP vent solenoid (located behind right rear wheelwell liner). Using scan tool, command EVAP vent solenoid on. Monitor EVAP vent circuit for short to voltage. If scan tool feedback does not read YES, replace EVAP vent solenoid. If scan tool feedback reads YES, check for short to voltage in circuit between instrument panel fuse block and PCM harness connector J2 terminal No. 58 (White wire). See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
  22. Turn ignition on, with engine off. Using scan tool, command EVAP purge solenoid on. Monitor EVAP purge circuit. If scan tool feedback reads YES, go to next step. If scan tool feedback does not read YES, problem is intermittent. See DIAGNOSTIC AIDS .
  23. Disconnect EVAP purge solenoid (located on rear of air cleaner box). Using scan tool, command EVAP purge solenoid on. Monitor EVAP purge circuit for short to voltage. If scan tool feedback does not read YES, replace EVAP purge solenoid. If scan tool feedback reads YES, check for short to voltage in circuit between EVAP purge solenoid and PCM harness connector J2 terminal No. 56 (Dark Green/White wire). See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace PCM.
scientia non olet · About LEMON Manuals