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Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check for related service bulletins. Repair as necessary and go to next step.
  2. Using scan tool, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Turn ignition switch off and on. Recheck DTCs. If DTC P1624 is present, go to step  10 . If DTC P1624 is not present, go to next step.
  3. Disconnect immobilizer unit connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  19 . If connector terminals are okay, go to next step.
  4. Check for continuity between immobilizer unit harness connector terminal "C" (Black/Orange wire) and ground. See Fig 1 . If continuity is not present, repair open circuit. See WIRING DIAGRAMS article. Repair as necessary and go to step  19 . If continuity is present, go to next step.
  5. Disconnect immobilizer system coil connector, located behind ignition lock cylinder. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  19 . If connector terminals are okay, go to next step.
  6. Check for continuity between ground and immobilizer system coil connector terminal "A" (Green wire). If continuity is not present, go to next step. If continuity is present, replace immobilizer system coil connector and go to step  19 .
  7. Reconnect immobilizer system coil connector. Check for continuity between immobilizer unit harness connector terminal "F" (Yellow/Green wire) and ground. See Fig 1 . If continuity is not present, go to next step. If continuity is present, repair short to ground in Yellow/Green wire and Green wire between immobilizer system coil and immobilizer unit. See WIRING DIAGRAMS article. Repair as necessary and go to step  19 .
  8. Disconnect PCM connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  19 . If connector terminals are okay, go to next step.
  9. Check for continuity of Pink/Black wire between immobilizer unit harness connector terminal "A" and PCM harness connector terminal No. 5. See Figure and Fig 1 . If continuity is present, go to step  19 . If continuity is not present, repair open in Pink/Black wire between immobilizer unit and PCM. See WIRING DIAGRAMS article. Repair as necessary and go to step  19 .
  10. Recheck DTCs. If DTC P1602 is present, go to step  14 . If DTC P1602 is not present, go to next step.
  11. Disconnect immobilizer system coil connector, located behind ignition lock cylinder. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  19 . If connector terminals are okay, go to next step.
  12. Check for continuity between immobilizer system coil connector terminals. If continuity is present, go to next step. If continuity is not present, replace immobilizer system coil and go to step  19 .
  13. Reconnect immobilizer system coil connector. Ensure immobilizer unit connector is disconnected. Check for continuity between immobilizer unit harness connector terminals "D" (Green wire) and "F" (Yellow/Green wire). See Fig 1 . If continuity is present, go to step  19 . If continuity is not present, repair open circuit in Yellow/Green or Green wire between immobilizer system coil and immobilizer unit. Go to step  19 .
  14. Recheck DTCs. If DTC 03 is present, key does not have a transponder. Change to a registered key and go to step  19 . If DTC 03 is not present, go to next step.
  15. If DTC 01 is present, use another key or register key currently being used. See KEY REPLACEMENT OR ADDITION under PROGRAMMING. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. Go to step  19 . If DTC 01 is not present, go to next step.
  16. Disconnect immobilizer unit connector. Check for loose, damaged or corroded connector terminals. Repair as necessary, and go to step  19 . If connector terminals are okay, go to next step.
  17. Turn ignition on. Measure voltage between ground and immobilizer unit harness connector terminal "J" (Blue/Red wire). See Fig 1 . If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit. See WIRING DIAGRAMS article. Repair as necessary and go to step  19 .
  18. Check for continuity between immobilizer unit harness connector terminal "A" (Pink/Black wire) and ground. If continuity is not present, go to next step. If continuity is present, repair short to ground in Pink/Black wire between immobilizer unit and PCM. See WIRING DIAGRAMS article. Repair as necessary and go to next step.
  19. Reconnect all electrical connections. Using scan tool, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Turn ignition off and start engine. Recheck DTCs. If DTC P1602 is present, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If DTC P1602 is not present, go to next step.
  20. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
Fig 1: Identifying Immobilizer Unit Harness Connector Terminals
G00020985Courtesy of MAZDA MOTORS CORP.
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