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HOMESERVICE MANUALSCADILLAC2000DEVILLE DHSREPAIR AND DIAGNOSISBODY & FRAMESEATSMEMORY SYSTEMSSYSTEM TESTSLUMBAR SUPPORT DOES NOT MOVE IN OR OUT
2000 Cadillac DeVille DHS

Lumbar Support Does Not Move In Or Out

2000 Cadillac DeVille DHSSECTION Lumbar Support Does Not Move In Or Out
NOTE: This procedure applies to vehicles equipped with memory systems (A45). For option code definition, see REGULAR PRODUCTION OPTION CODES  under DESCRIPTION.
  1. If power seats diagnostic system check was performed, go to next step. If power seats diagnostic system check was not performed, go to POWER SEATS DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC TESTS.
  2. Connect scan tool to Data Link Connector (DLC). See Figure . Turn ignition on. Using scan tool, select Memory Seat Module data list. Monitor SEAT LUMBAR FORWARD status. Operate driver's lumbar switch in forward direction. If SEAT LUMBAR FORWARD status changes, go to next step. If SEAT LUMBAR FORWARD status does not change, go to step  5 .
  3. Monitor SEAT LUMBAR BACKWARD status. Operate driver's lumbar switch in forward direction. If SEAT LUMBAR BACKWARD status changes, go to next step. If SEAT LUMBAR BACKWARD status does not change, go to step  6 .
  4. Disconnect lumbar horizontal motor connector. See Figure . Connect a test light between lumbar horizontal motor connector terminals "A" (Dark Blue wire) and "B" (Pink wire). Operate driver's lumbar switch in forward and backward directions. If test light does not illuminate in both directions, go to step  7 . If test light illuminates in both directions, go to step  13 .
  5. Disconnect driver's lumbar switch connector. Connect a 3-amp fused jumper wire between lumbar switch connector terminals "F" (Light Green wire) and "G" (Orange wire). See Figure . Monitor SEAT LUMBAR FORWARD status. If SEAT LUMBAR FORWARD status does not change, go to step  9 . If SEAT LUMBAR FORWARD status changes, go to step  12 .
  6. Disconnect driver's lumbar switch connector. Connect a 3-amp fused jumper wire between lumbar switch connector terminals "A" (Dark Green wire) and "G" (Orange wire). See Figure . Monitor SEAT LUMBAR BACKWARD status. If SEAT LUMBAR BACKWARD status does not change, go to step  10 . If SEAT LUMBAR BACKWARD status changes, go to step  12 .
  7. Check for short to ground or open in Dark Blue wire between Memory Seat Module (MSM) connector C3 terminal "B" and lumbar horizontal motor connector terminal "A". See Figure . If circuit is okay, go to next step. If faulty circuit is found and repaired, go to step  17 .
  8. Check for short to ground or open in Pink wire between MSM connector C3 terminal "L" and lumbar horizontal motor connector terminal "B". If circuit is okay, go to step  11 . If faulty circuit is found and repaired, go to step  17 .
  9. Check for short to ground or open in Light Green wire between Memory Seat Module (MSM) connector C2 terminal E10 and lumbar switch connector terminal "F". See Figure . If circuit is okay, go to step  11 . If faulty circuit is found and repaired, go to step  17 .
  10. Check for short to ground or open in Dark Green wire between Memory Seat Module (MSM) connector C2 terminal E9 and lumbar switch connector terminal "A". See Figure . If circuit is okay, go to next step. If faulty circuit is found and repaired, go to step  17 .
  11. Check for poor connections at MSM connector. If connections are okay, go to step  14 . If faulty connections are found and repaired, go to step  17 .
  12. Check for poor connections at driver's lumbar switch connector. If connections are okay, go to step  15 . If faulty connections are found and repaired, go to step  17 .
  13. Check for poor connections at lumbar horizontal motor connector. If connections are okay, go to step  16 . If faulty connections are found and repaired, go to step  17 .
  14. Replace MSM. See MEMORY SEAT MODULE  under REMOVAL & INSTALLATION. After repairs, go to step  17 .
  15. Replace driver's lumbar switch. See DRIVER'S POWER SEAT SWITCH  under REMOVAL & INSTALLATION. After repairs, go to step  17 .
  16. Replace seat lumbar horizontal motor. See SEAT MOTORS under REMOVAL & INSTALLATION in POWER SEATS - DEVILLE article. After repairs, go to next step.
  17. Recheck power lumbar operation. If power lumbar malfunction is still present, go to step  2 . If power lumbar malfunction is no longer present, repair is complete.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.