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Speedometer/Odometer Is Inoperative Or Inaccurate

  1. If instrument cluster diagnostic system check was performed, go to next step. If instrument cluster diagnostic system check was not performed, go to INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  2. Connect scan tool. Using scan tool, check for instrument cluster DTCs. If no DTCs exist, go to next step. If any DTCs exist, go to SELF-DIAGNOSTIC SYSTEM  .
  3. Turn ignition switch to RUN position. Using scan tool, establish communication with instrument cluster. Select SPECIAL FUNCTIONS under main menu. Select OUTPUT CONTROL. Select SPEEDOMETER GAUGE SWEEP TEST. Speedometer gauge should perform a full sweep when commanded. If speedometer gauge does not operate as specified, go to next step. If speedometer gauge operates as specified, go to step  5 .
  4. Replace instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Recheck system operation.
  5. Drive vehicle and compare vehicle speed displayed on scan tool to speed displayed on speedometer gauge. If both speeds are similar, go to next step. If both speeds are not similar, go to step  9 .
  6. If both speedometer and odometer are inaccurate, go to next step. If only speedometer or odometer is inaccurate, go to step  10 .
  7. Check vehicle for correct tire size, PCM calibration and vehicle speed sensor application. If these component applications are not correct, go to next step. If these component applications are okay, diagnose and repair problem in vehicle speed sensor system. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  8. Replace tires or vehicle speed sensor, or recalibrate PCM as necessary. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. Recheck system operation.
  9. Check operation of cruise control system. If cruise control is also malfunctioning, go to step  12 . If cruise control is operating properly, go to next step.
  10. Check for excessive resistance, open or short (to ground or battery) in Dark Green/White wire between instrument cluster Gray 24-pin connector terminal B10 and PCM Blue 80-pin connector C1, terminal No. 55. If circuit is not okay, go to next step. If circuit is okay, go to step  4 .
  11. Repair excessive resistance, open or short (to ground or battery) in Dark Green/White wire between instrument cluster and PCM connector C1. Recheck system operation.
  12. Disconnect cruise control module connector. Using DVOM, check voltage between cruise control module harness connector terminal "K" (Dark Green/White wire) and ground. Voltage should be 5 volts or more, but less than battery voltage. If voltage is as specified, go to step  14 . If voltage is not as specified, go to next step.
  13. Check for excessive resistance, open or short (to ground or battery) in Dark Green/White wire between cruise control module and PCM connector C1. Repair as necessary and recheck system operation. If circuit is okay, check for internal shorts in cruise control module. Replace as necessary and recheck system operation.
  14. Leave DVOM connected as specified in step 12)  . Turn ignition switch to RUN position. Rotate a drive wheel slowly by hand in forward direction. Voltage should vary between less than one volt and more than 2.5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step  16 .
  15. Check for poor connection at cruise control module. Repair as necessary and recheck system operation. If connection is okay, replace cruise control module. See appropriate CRUISE CONTROL SYSTEMS article. Recheck system operation.
  16. Reconnect cruise control module. Disconnect PCM Blue 80-pin connector C1. Using DVOM, check voltage between PCM harness connector C1, terminal No. 55 (Dark Green/White wire) and ground. Turn ignition switch to RUN position. Voltage should be 5 volts or more, but less than battery voltage. If voltage is as specified, go to next step. If voltage is not as specified, go to step  18 .
  17. Check for poor connection at PCM. Repair as necessary and recheck system operation. If connection is okay, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Recheck system operation.
  18. Repair excessive resistance, open or short (to ground or battery) in Dark Green/White wire between cruise control module and PCM connector C1. Recheck system operation.
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