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Cruise Control Inoperative/Malfunctioning

NOTE: To avoid misdiagnosis, ensure preliminary inspection and all checks have been performed. See TROUBLE SHOOTING  . Ensure proper operation of brakelight system.
  1. Perform cruise control diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After completing system check, go to next step.
  2. Turn ignition switch to OFF position. Disconnect cruise control module harness connector. Turn ignition switch to ON position. Using a test light connected to ground, probe ignition feed circuit at cruise control module harness connector (harness side) terminal "F" (Pink wire). See WIRING DIAGRAMS  . If test light illuminates, go to next step. If test light does not illuminate, go to step  36 .
  3. Using a test light connected to cruise control module ground circuit at cruise control module harness connector terminal "E" (Black wire on DeVille; Black/White wire on Eldorado), probe ignition feed circuit at cruise control module harness connector terminal "F" (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  37 .
  4. Turn ignition switch to ON position. Ensure cruise control switch is in OFF position. Using a test light connected to chassis ground, individually probe cruise control harness connector terminals "A" (Gray wire), "B" (Dark Blue wire) and "C" (Gray/Black wire). If test light does not illuminate, go to next step. If test light illuminates at any terminal, go to step  16 .
  5. Turn ignition and cruise control switches to ON position. Using a test light connected to chassis ground, probe cruise control 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. Using a test light connected to chassis ground, probe cruise control module 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. Using a test light connected to chassis ground, probe cruise control module 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. Press brake pedal and observe test light. If test light does not illuminate, go to next step. If test light illuminates, go to step  21 .
  9. While monitoring test light at Purple wire (terminal "D"), depress brake pedal. If test light does not illuminate, go to next step. If test light illuminates, go to step  22 .
  10. Using a test light, probe cruise control module harness connector terminal "G" (White wire on DeVille; Light Blue wire on Eldorado). If test light does not illuminate, go to next step. If test light illuminates, go to step  23 .
  11. While monitoring test light at cruise control module harness connector terminal "G" (White wire on DeVille; Light Blue wire on Eldorado), depress brake pedal. If test light illuminates, go to next step. If test light does not illuminate, go to step  24 .
  12. Using a test light connected to battery voltage, probe cruise control module 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. With test light connected to Dark Green wire (terminal "H"), connect scan tool to DLC. 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 connected to ground, probe cruise control module harness connector terminal "J" (Light Blue/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, go to step  27 .
  15. Raise and support vehicle. Block one drive wheel and place transaxle in DRIVE position. Using DVOM set to AC scale, measure voltage at cruise control module harness connector terminal "K" (Dark Green/White wire) while rotating one drive wheel. If voltage fluctuates, go to step  28 . If voltage does not fluctuate, see appropriate INSTRUMENT PANELS article.
  16. Repair short to voltage in wire which caused test light to come on in step 4)  . See WIRING DIAGRAMS  . After repair, go to step  43 . If no problem was found or condition still exists, go to step  34 .
  17. Check Gray wire between cruise control functional switches and cruise control harness connector terminal "A" for open or high resistance. Also check ignition feed circuit (Pink wire) between ABS/TCC switch and rear compartment fuse block. See WIRING DIAGRAMS  . Repair circuit as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to next step.
  18. Check ignition feed circuit (Pink wire) between cruise control functional switches harness connector terminal and rear compartment fuse block. See WIRING DIAGRAMS  . After repair, go to step  43 . If no problem was found or condition still exists, go to step  34 .
  19. Check Dark Blue wire between cruise control functional switches harness connector terminal No. 1 (5-pin connector terminal No. 5 on DeVille) and cruise control module harness connector terminal "B" for open or high resistance. See WIRING DIAGRAMS  . Repair Dark Blue wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  34 .
  20. Check Gray/Black wire between cruise control functional switches harness connector terminal No. 4 (5-pin connector terminal No. 4 on DeVille) "C" and cruise control module harness connector terminal "C" for open or high resistance. See WIRING DIAGRAMS  . Repair Gray/Black wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  34 .
  21. Check Purple wire between ABS/TCC switch harness connector and cruise control module harness connector terminal "D" for open or high resistance. See WIRING DIAGRAMS  . Repair Purple wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  29 .
  22. Check Purple wire between ABS/TCC switch harness connector and cruise control module harness connector terminal "D" for short to voltage. See WIRING DIAGRAMS  . Repair Purple wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  29 .
  23. Check White wire (Light Blue wire on Eldorado) between brakelight/automatic transmission shift lock control switch harness connector and cruise control module harness connector terminal "G" for short to voltage. See WIRING DIAGRAMS  . After repair, go to step  43 . If no problem was found or condition still exists, go to step  30 .
  24. Check White wire (Light Blue wire on Eldorado) between brakelight/automatic transmission shift lock control switch harness connector and cruise control module harness connector terminal "G" for open or high resistance. See WIRING DIAGRAMS  . After repair, go to step  43 . If no problem was found or condition still exists, go to step  30 .
  25. Check Dark Green wire between cruise control module harness connector terminal "H" and Blue PCM harness connector C1 terminal No. 35 for short to ground. See WIRING DIAGRAMS  . Repair Dark Green wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  33 .
  26. Check Dark Green wire between cruise control module harness connector terminal "H" and Blue PCM harness connector C1 terminal No. 35 for an open, high resistance or short to voltage. See WIRING DIAGRAMS  . Repair Dark Green wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  33 .
  27. Check Light Blue/Black wire between cruise control module harness connector terminal "J" and Clear PCM harness connector C2 terminal No. 24 for an open, high resistance or short to voltage. See WIRING DIAGRAMS  . Repair Light Blue/Black wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  33 .
  28. Check Dark Green/White wire between cruise control module harness connector terminal "K" and Blue PCM harness connector C1 terminal No. 26 for open or high resistance. See WIRING DIAGRAMS  . Repair Dark Green/White wire as necessary. Repair Light Blue/Black wire as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  35 .
  29. Check ABS/TCC switch for proper adjustment. See ABS/TCC SWITCH  under ADJUSTMENTS. Adjust switch if necessary. After adjustment, go to step  43 . If no problem was found or condition still exists, go to step  31 .
  30. Check brakelight/automatic transmission shift lock control switch proper adjustment. See BRAKELIGHT/AUTOMATIC TRANSMISSION SHIFT LOCK CONTROL SWITCH  under ADJUSTMENTS. Adjust switch if necessary. After adjustment, go to step  43 . If no problem was found or condition still exists, go to step  32 .
  31. Check for poor connections or connector damage at ABS/TCC switch harness connector. Repair as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  38 .
  32. Check for poor connections or connector damage at brakelight/automatic transmission shift lock control switch harness connector. Repair as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  39 .
  33. Check for poor harness connections at PCM. Repair connections as necessary. Repair as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  40 .
  34. Check for poor connections or connector damage at cruise control functional switches harness connector. Repair as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  41 .
  35. Check for poor connections or connector damage at cruise control module harness connector. Repair as necessary. After repair, go to step  43 . If no problem was found or condition still exists, go to step  42 .
  36. Repair ignition feed circuit (Pink wire) as necessary between cruise control module harness connector terminal "B" and CRUISE fuse (10-amp) in underhood fuse block. chassis ground. After repair, go to step  43 .
  37. Repair ground circuit (Black wire on DeVille; Black/White wire on Eldorado) as necessary between cruise control module harness connector terminal "E" and ground point connection. See WIRING DIAGRAMS  . After repair, go to step  43 .
  38. Replace ABS/TCC switch. See ABS/TCC SWITCH  under REMOVAL & INSTALLATION. Adjust ABS/TCC switch. See ABS/TCC SWITCH  under ADJUSTMENTS. After repair, go to step  43 .
  39. Replace brakelight/automatic transmission shift lock control switch. See BRAKELIGHT/AUTOMATIC TRANSMISSION SHIFT LOCK CONTROL SWITCH  under REMOVAL & INSTALLATION. Adjust brakelight/automatic transmission shift lock control switch. See BRAKELIGHT/AUTOMATIC TRANSMISSION SHIFT LOCK CONTROL SWITCH  under ADJUSTMENTS. After repair, go to step  43 .
  40. Replace and program PCM. See POWERTRAIN CONTROL MODULE (PCM)  under REMOVAL & INSTALLATION. To program PCM, see COMPUTER RELEARN PROCEDURES - GENERAL MOTORS CORP. article in GENERAL INFORMATION. After repair, go to step  43 .
  41. Replace cruise control functional switches. See CRUISE CONTROL FUNCTIONAL SWITCHES  under REMOVAL & INSTALLATION. After repair, go to step  43 .
  42. Replace cruise control module. See CRUISE CONTROL MODULE  under REMOVAL & INSTALLATION. After repair, go to next step.
  43. Operate vehicle at normal highway speeds and exercise cruise control system. If cruise control system operates correctly, repair is complete. If cruise control system is not operating properly, return to step  2 .
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