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Test D - Speedometer/Odometer Inaccurate

  1. Turn ignition off. Connect New Generation Star (NGS) Tester (007-00500), and retrieve Diagnostic Trouble Codes (DTC) following manufacturer's instructions. If no DTCs are present, go to next step. If DTCs are present, see TESTS W/CODES article in ENGINE PERFORMANCE section. Repair DTCs as necessary, then retest system.
  2. Using NGS tester, observe Vehicle Speed Sensor (VSS) output Parameter Identification (PID) while assistant drives vehicle over range of speeds on various road surfaces. If VSS PID varies smoothly with vehicle speed, go to next step. If VSS PID does not vary or is erratic, see TESTS W/CODES article in ENGINE PERFORMANCE section.
  3. Remove and check ROOM fuse. See Figure . If fuse is okay, reinstall fuse and go to step 5). If fuse is blown, go to next step.
  4. Turn ignition off. Remove instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect instrument cluster electrical connector C2. See Figure . Measure resistance between ground and instrument cluster harness connector C2, terminal No. 12 (Blue/Red wire). Resistance should be greater than 10 k/ohms. If resistance is greater than 10 k/ohms, replace ROOM fuse and go to next step. If resistance is less than 10 k/ohms, repair Blue/Red wire between instrument cluster harness connector and fuse. See WIRING DIAGRAMS  .
  5. Measure voltage between ground and instrument cluster harness connector C2, terminal No. 12 (Blue/Red wire). See Figure . Voltage should be greater than 10 volts. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair Blue/Red wire between instrument cluster harness connector and fuse. See WIRING DIAGRAMS  .
  6. Turn ignition off. Disconnect Vehicle Speed Sensor (VSS) harness connector. Measure resistance between VSS harness connector Blue wire and instrument cluster harness connector C2, terminal No. 7 (Blue wire). See Figure . Measure resistance between VSS harness connector White/Black wire and instrument cluster harness connector C2, terminal No. 9 (White/Black wire). Resistance in both tests should be less than 5 ohms. Measure resistance between ground and instrument cluster harness connector C2, terminal No. 9 (White/Black wire). Resistance should be greater than 10 k/ohms. If resistances are as specified, go to next step. If resistances are not as specified, repair wire in question. See WIRING DIAGRAMS  .
  7. Turn ignition on. Measure voltage between ground and instrument cluster harness connector C2, terminal No. 8 (Black/Yellow wire). See Figure . Voltage should be greater than 10 volts. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair Black/Yellow wire between instrument cluster connector and fuse. See WIRING DIAGRAMS  .
  8. Turn ignition off. Visually inspect instrument cluster printed circuit for damage, cracks or hot spots. If instrument cluster printed circuit is okay, replace speedometer. If instrument cluster printed circuit is damaged, replace printed circuit and gauge contact clips. See PRINTED CIRCUIT  under REMOVAL & INSTALLATION.
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