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Home >> Mazda >> 2002 >> MX-5 Miata Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0500: Vehicle Speed Sensor Malfunction >> Diagnostic Procedure

Diagnostic Procedure

  1. Turn ignition off. Connect New Generation Star (NGS) tester or equivalent to OBD-II Data Link Connector-2 (DLC-2). See Figure. Turn ignition on. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check for service bulletins and/or other line of repair information related to this DTC. If repair information is available, perform diagnosis and repair as necessary. After repair, go to step  17. If repair information is not available, go to next step.
  2. Start engine and drive vehicle. Check for speedometer needle to move while driving. If speedometer needle does move when driving, go to next step. If speedometer needle does not move when driving. For vehicle equipped with manual transmission (M/T), go to step  7. For vehicle equipped with automatic transmission (A/T), go to step  11.
  3. Stop engine and leave ignition on. Using NGS tester or equivalent, clear DTCs from PCM memory. Start engine and let it idle until it reaches normal operation temperature. Access LOAD and RPM PIDs. Drive vehicle under following conditions:
    • LOAD PID: 40 percent or above.
    • RPM PID: 2000 RPM or above.

    Monitor for DTCs. If same DTC P0500 is present, go to next step. If DTC P0500 is not present, go to step  5.

  4. Turn ignition off. Disconnect cruise control module, instrument cluster and PCM 24-pin harness connectors. See Fig 1. Check continuity between ground and PCM connector terminal "3T" (Green/Red wire). If continuity is found, repair short circuit to ground (in Green/Red wire) between PCM and cruise control module or instrument cluster. After repair, go to step  17. If continuity is not found, replace speedometer. After repair, go to step  17. For circuit identification, see MIATA in WIRING DIAGRAMS article.
  5. With PCM harness connector disconnected, check for poor connection at PCM connector terminals due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are found faulty, repair or replace as necessary and go to step  17.
  6. With PCM and instrument cluster harness connector disconnected, check continuity between PCM harness connector terminal "3T" and instrument cluster connector terminal "2L" (Green/Red wire). If continuity is found, go to step  17. If continuity is not found, repair open circuit (in Green/Red wire) between PCM and instrument cluster. After repair, go to step  17.
  7. Leave instrument cluster harness disconnected and disconnect VSS 2-pin harness connector. See Fig 1. Check continuity between connector terminals as follow:
    • Between VSS connector terminal "A" and instrument cluster connector terminal "2M" (Orange wire).
    • Between VSS connector terminal "B" and instrument cluster connector terminal "1M" (Yellow wire).

    If continuity is found, go to next step. If continuity is not found, repair open circuit (in either Orange or Yellow wire) between instrument cluster and VSS, After repair, go to step  17.

  8. With instrument cluster and VSS harness connector disconnected, check continuity between VSS connector terminal "A" (Orange wire)and "B" (Yellow wire). If continuity is not found, go to next step. If continuity is found, repair short circuit between VSS wires (Orange and Yellow wires). After repair, go to step  17.
  9. With instrument cluster and VSS harness connector disconnected, check continuity at instrument cluster connector terminals as follow:
    • Between ground and instrument cluster connector terminal "1M" (Yellow wire).
    • Between ground and instrument cluster connector terminal "2M" (Orange wire).

    If continuity is not found, go to next step. If continuity is found, repair short circuit to ground (in either Yellow or Orange wire) between instrument cluster and VSS. After repair, go to step 17.

  10. Remove VSS. Inspect voltage between VSS connector terminals "A" and "B" (component side). For proper component test see VEHICLE SPEED SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE, PROTEGE5 & 626 article. If voltage is as specified, inspect speedometer and go to step  17. If voltage is no as specified, replace VSS. After repair, go to step  17.
  11. Leave instrument cluster harness connector disconnected and disconnect TCM 35-pin harness connector. See Fig 1. Check continuity between ground and TCM harness connector terminal "AC" (Black/White wire). If continuity is not found, go to next step. If continuity is found, repair short circuit to ground (in Black/White wire) between instrument cluster and TCM. After repair, go to step  17.
  12. With instrument cluster and TCM harness connector disconnected, check continuity between instrument cluster connector terminal "2M" and TCM harness connector terminal "AC" (Black/White wire). If continuity is found, go to next step. If continuity is not found, repair open circuit (in Black/White wire) between instrument cluster and TCM. After repair, go to step  17.
  13. Leave TCM harness connector disconnected and disconnect output speed sensor. See Fig 1. Check continuity between TCM and output speed sensor conductor terminals as follow:
    • Between output speed sensor connector terminal "A" and TCM connector terminal "AE" (Yellow wire).
    • Between output speed sensor connector terminal "B" and TCM connector terminal "AF" (Orange wire).

    If continuity is found, go to next step. If continuity is not found, repair open circuit (in either Yellow or Orange wire) between output speed sensor and TCM. After repair, go to step  17.

  14. With TCM and output speed sensor harness connector disconnected, check continuity between output speed sensor harness connector terminals "A" (Yellow wire) and "B" (Orange wire). If continuity is not found, go to next step. If continuity is found, repair short circuit between output speed sensor wires (Yellow and Orange wires). After repair, go to step  17.
  15. With TCM and output speed sensor harness connector disconnected, check continuity at TCM connector terminal as follow:
    • Between ground and TCM harness connector terminal "AE" (Yellow wire).
    • Between ground and TCM harness connector terminal "AF" (Orange wire).

    If continuity is not found, go to next step. If continuity is found, repair short to ground circuit (in either Yellow or Orange wire) between body ground and TCM. After repair, go to step  17.

  16. With output speed sensor harness connector disconnected, measure resistance between output speed sensor connector terminals "A" and "B" (component side). Resistance should be 387-473 ohms at 68°F (20°C). If resistance is as specified, inspect vehicle speedometer and go to next step. If resistance is not as specified, replace output speed sensor. After repair, go to next step.
  17. Return vehicle to original condition. Using NGS tester or equivalent, clear DTCs from PCM memory. Start engine and let it idle until it reaches normal operation temperature. Access LOAD and RPM PIDs. Drive vehicle under following conditions:
    • LOAD PID: 40 percent or above.
    • RPM PID: 2000 RPM or above.

    Monitor for DTCs. If same DTC P0500 is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE in REMOVAL, OVERHAUL & INSTALLATION article. If any other DTC is present, follow appropriate DTC diagnostic procedure.

Fig 1: Identifying Instrument Cluster, Transmission Control Module, Vehicle Speed Sensor & Output Speed Sensor Connector Terminals
G00140069Courtesy of MAZDA MOTORS CORP.
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