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Home >> Mazda >> 2003 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P2401: EVAP System Leak Detection Pump Motor Circuit - Low Input >> Diagnostic Procedure
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Diagnostic Procedure

  1. Verify Related Repair Information Availability -  Turn ignition off. Connect scan tool to DLC-2. See Figure. Turn ignition on, engine off. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check service bulletins for repair information related to this DTC. If repair information is not available, go to next step. If repair information is available, perform diagnosis and repair as necessary. After repair, go to next step.
  2. Verify Related Pending Code Or Stored DTCs -  Turn ignition off, then on (engine off). Verify related Pending Code or stored DTCs. If DTC P2405 is not present with P2401, go to next step. If DTC P2405 is present with P2401, go to DTC P2405: EVAP SYSTEM LEAK DETECTION PUMP ORIFICE FALLEN OFF .
  3. Inspect Poor Connection Of EVAP System Leak Detection Pump Connector -  Turn ignition off. Disconnect EVAP system leak detection pump 4-pin harness connector. See Fig 1. Check for poor connection at EVAP system leak detection pump connector terminals due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are faulty, repair or replace as necessary. After repair, go to step  9.
    Fig 1: Identifying EVAP System Leak Detection Pump 4-Pin Harness Connector & Terminals
    G00158952Courtesy of MAZDA MOTORS CORP.
  4. Inspect EVAP System Leak Detection Pump Motor Circuit For Open -  Disconnect main relay. Check continuity between EVAP system leak detection pump 4-pin harness connector terminal "A" and main relay 4-pin harness connector terminal "D" (White/Red wire). If continuity is present, go to next step. If continuity is not present, repair open circuit in White/Red wire between EVAP system leak detection pump 4-pin harness connector terminal "A" and main relay 4-pin harness connector terminal "D". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  9.
  5. Inspect Poor Connection Of PCM Connector -  Turn ignition off. Disconnect PCM 31-pin harness connector. See Figure. Check for poor connection at VTCS connector terminals due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are faulty, repair or replace as necessary. After repair, go to step  9.
  6. Inspect EVAP System Leak Detection Pump Motor Circuit For Short To Ground -  Check continuity between ground and EVAP system leak detection pump 4-pin harness connector terminal "D" (Yellow/Black wire). If continuity is not present, go to next step. If continuity is present, repair short circuit to ground in Yellow/Black wire between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K". After repair, go to step  9.
  7. Inspect EVAP System Leak Detection Pump Motor Circuit For Open Circuit -  Check continuity between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K" (Yellow/Black wire). If continuity is present, go to next step. If continuity is not present, repair open circuit in Yellow/Black wire between EVAP system leak detection pump 4-pin harness connector terminal "D" and PCM 24-pin harness connector terminal "3K". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  9.
  8. Inspect EVAP System Leak Detection Pump -  Perform EVAP system leak detection pump inspection. See FUEL EVAPORATIVE SYSTEM (MIATA & MPV) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If EVAP system leak detection pump is okay, go to next step. If EVAP system leak detection pump is faulty, replace EVAP system leak detection pump. After repair, go to next step.
  9. Verify Troubleshooting Of DTC P2401 Completed -  Return vehicle to original condition. Using scan tool, clear DTCs from PCM memory. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and run DRIVE MODES 1, 2 and 3. See DRIVE MODES  under SELF-DIAGNOSTIC SYSTEM.Monitor for pending DTCs. If same DTC is not present, go to next step. If same DTC P2401 is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to next step.
  10. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
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