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Test D: Cruise Control Inoperative/Malfunctioning

  1. If cruise control diagnostic system check has been performed, go to next step. If cruise control diagnostic system check has not been performed, perform appropriate CRUISE CONTROL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM  .
  2. Turn ignition switch to OFF position. Disconnect Cruise Control Module (CCM) 10-pin harness connector. On DeVille, CCM is located left side of firewall, near brake booster. On Eldorado, CCM is located on left front strut tower. On all models, turn ignition switch to RUN position. Connect a test light between ground and CCM harness connector terminal "F" (Pink wire). See Figure . If test light illuminates, go to next step. If test light does not illuminate, go to step  36 .
  3. Using a test light between CCM harness connector terminals "F" (Pink wire) and "E" (Black wire on DeVille or Black/White wire on Eldorado). If test light illuminates, go to next step. If test light does not illuminate, go to step  37 .
  4. Turn ignition switch to OFF position. Using a test light connected to ground, probe CCM harness connector terminals "A" (Gray wire), "B" (Dark Blue wire) and "C" (Gray/Black wire). See Figure . If test light does not illuminate at any terminal, go to next step. If test light illuminates at any terminal, go to step  16 .
  5. Turn cruise control switch on. Connect a test light between ground and CCM harness connector terminal "A" (Gray wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  17 .
  6. Connect a test light between ground and CCM harness connector terminal "B" (Dark Blue wire). Press and hold SET/COAST switch. If test light illuminates, go to next step. If test light does not illuminate, go to step  19 .
  7. Connect a test light between ground and CCM harness connector terminal "C" (Gray/Black wire). Press and hold RESUME/ACCEL switch. If test light illuminates, go to next step. If test light does not illuminate, go to step  20 .
  8. Connect a test light between ground and CCM harness connector terminal "D" (Purple wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  21 .
  9. Ensure test light is still connected between ground and CCM harness connector terminal "D" (Purple wire). Press brake pedal while monitoring test light. If test light does not illuminate with brake pedal applied, go to next step. If test light illuminates with brake pedal applied, go to step  22 .
  10. Connect a test light between ground and CCM harness connector terminal "G" (White wire on DeVille or Light Blue wire on Eldorado). See Figure . If test light does not illuminate, go to next step. If test light illuminates, go to step  23 .
  11. Ensure test light is still connected between ground and CCM harness connector terminal "G". Press brake pedal while monitoring test light. If test light illuminates with brake pedal applied, go to next step. If test light does not illuminate with brake pedal applied, go to step  24 .
  12. Connect a test light between battery voltage and CCM harness connector terminal "H" (Dark Green wire). If test light does not illuminate, go to next step. If test light illuminates, go to step  25 .
  13. Ensure test light is still connected between battery voltage and CCM harness connector terminal "H". Using scan tool, command cruise inhibit/enable OFF. If test light illuminates, go to next step. If test light does not illuminate, go to step  26 .
  14. Using a DVOM, measure voltage between ground and CCM harness connector terminal "J" (Light Blue/Black wire). If voltage exists, go to next step. If voltage does not exist, go to step  27 .
  15. Test drive vehicle and observe speedometer operation. If speedometer operates correctly, go to step  28 . If speedometer does not operate correctly, repair speedometer as necessary. See appropriate ANALOG INSTRUMENT PANELS article.
  16. Inspect signal circuit which illuminated test light for a short to voltage. See WIRING DIAGRAMS  . If a short to voltage is not found, go to step  34 . If a short to voltage is found, repair signal circuit as necessary. After repair, go to step  43 .
  17. Inspect Gray wire for an open or high resistance between cruise control on/off switch and CCM harness connector terminal "A". If an open or high resistance is not found, go to next step. If an open or high resistance is found, repair Gray wire as necessary. After repair, go to step  43 .
  18. Inspect Pink wire for an open or high resistance between cruise control switch and rear fuse block. If an open or high resistance is not found, go to step  34 . If an open or high resistance is found, repair Pink wire as necessary. After repair, go to step  43 .
  19. Inspect Dark Blue wire for an open or high resistance between CCM harness connector terminal "B" and cruise control switch. If an open or high resistance is not found, go to step  34 . If an open or high resistance is found, repair Dark Blue wire as necessary. After repair, go to step  43 .
  20. Inspect Gray/Black wire for an open or high resistance between CCM harness connector terminal "C" and cruise control switch. If an open or high resistance is not found, go to step  34 . If an open or high resistance is found, repair Gray/Black wire as necessary. After repair, go to step  43 .
  21. Inspect Purple wire for an open or high resistance between CCM harness connector terminal "D" and stoplight switch (Eldorado) or TCC/cruise release switch (DeVille). If an open or high resistance is not found, go to step  29 . If an open or high resistance is found, repair Purple wire as necessary. After repair, go to step  43 .
  22. Inspect Purple wire for a short to voltage between CCM harness connector terminal "D" and stoplight switch (Eldorado) or TCC/cruise release switch (DeVille.) If a short to voltage is not found, go to step  29 . If a short to voltage is found, repair Purple wire as necessary. After repair, go to step  43 .
  23. Inspect stoplight signal circuit for a short to voltage between ground and CCM harness connector terminal "G" (White wire on DeVille or Light Blue wire on Eldorado). If a short to voltage is not found, go to step  30 . If a short to voltage is found, repair White wire or Light Blue wire as necessary. After repair, go to step  43 .
  24. Inspect stoplight signal circuit for an open or high resistance between stoplight switch and CCM harness connector terminal "G" (White wire on DeVille or Light Blue wire on Eldorado). If an open or high resistance is not found, go to step  30 . If an open or high resistance is found, repair White wire or Light Blue wire as necessary. After repair, go to step  43 .
  25. Inspect Dark Green wire for a short to ground between ground and CCM harness connector terminal "H". See Figure . If a short to ground is not found, go to step  33 . If a short to ground is found, repair Dark Green wire as necessary. After repair, go to step  43 .
  26. Inspect Dark Green wire for an open, high resistance or short to voltage between CCM harness connector terminal "H" and Powertrain Control Module (PCM) harness connector C1 terminal No. 35. See Figure and Figure . If an open, high resistance or short to voltage is not found, go to step  33 . If an open, high resistance or short to voltage is found, repair Dark Green wire as necessary. After repair, go to step  43 .
  27. Inspect Light Blue/Black wire for an open, high resistance or short to voltage between CCM harness connector terminal "J" and PCM harness connector C2 terminal No. 24. If an open, high resistance or short to voltage is not found, go to step  33 . If an open, high resistance or short to voltage is found, repair Light Blue/Black wire as necessary. After repair, go to step  43 .
  28. On DeVille, inspect Dark Gray/White wire for an open or high resistance between CCM harness connector terminal "K" and PCM harness connector C1 terminal No. 26. On Eldorado, inspect Dark Gray/White wire for an open or high resistance between CCM harness connector terminal "K" and Instrument Panel Cluster (IPC) harness connector C1 terminal B5. On all models, if an open or high resistance is not found, go to step  35 . If an open or high resistance is found, repair Dark Gray/White wire as necessary. After repair, go to step  43 .
  29. Inspect TCC/cruise release switch or brakelight switch for proper adjustment. See ANTI-LOCK BRAKE SYSTEM/TORQUE CONVERTER CLUTCH SWITCH (ELDORADO)  or BRAKELIGHT/AUTOMATIC TRANSMISSION SHIFT LOCK CONTROL SWITCH  under ADJUSTMENTS. If adjustment is okay, go to step  31 . If adjustment is not okay, adjust as necessary. After adjustment, go to step  43 .
  30. Inspect stoplight switch for proper adjustment. See STOPLIGHT SWITCH  under ADJUSTMENTS. If adjustment is okay, go to step  32 . If adjustment is not okay, adjust stoplight switch as necessary. After adjustment, go to step  43 .
  31. Inspect TCC/cruise release switch or brakelight switch harness connector for poor connections. If poor connections are not found, go to step  38 . If poor connections are found, repair TCC/cruise release switch or brakelight switch harness connector as necessary. After repair, go to step  43 .
  32. Inspect stoplight switch harness connector for poor connections. If poor connections are not found, go to step  39 . If poor connections are found, repair stoplight switch harness connector as necessary. After repair, go to step  43 .
  33. Inspect PCM harness connector for poor connections. If poor connections are not found, go to step  40 . If poor connections are found, repair PCM harness connector as necessary. After repair, go to step  43 .
  34. Inspect cruise control switch harness connector for poor connections. If poor connections are not found, go to step  41 . If poor connections are found, repair cruise control switch harness connector as necessary. After repair, go to step  43 .
  35. Inspect CCM harness connector for poor connections. If poor connections are not found, go to step  42 . If poor connections are found, repair CCM harness connector as necessary. After repair, go to step  43 .
  36. Repair open in Pink wire between CCM and underhood fuse block. After repair, go to step  43 .
  37. Repair open in ground circuit between ground and CCM harness connector terminal "E" (Black wire on DeVille or Black/White wire on Eldorado). On DeVille, ground point is located on left side of radiator support. On Eldorado, ground point is located on left side of engine, below EGR valve. After repair, go to step  43 .
  38. Replace TCC/cruise release switch or brakelight switch, then go to step  43 .
  39. Replace stoplight switch, then go to step  43 .
  40. Replace PCM. Program PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repair, go to step  43 .
  41. On DeVille, replace cruise control switch. On Eldorado, replace multifunction switch lever. On all models, after repair, go to step  43 .
  42. Replace CCM, then go to next step.
  43. Operate cruise control system to verify repair. If system is not operating correctly, repeat test beginning at step  2 .
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