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Home >> Mazda >> 2003 >> Protege5 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0703: Brake Switch Input Circuit Malfunction >> Diagnostic Procedure

Diagnostic Procedure

  1. Verify Related Repair Information Availability -  Turn ignition off. Connect scan tool to DLC-2. 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 step  8.
  2. Inspect Brake Switch Signal Circuit For Short To Power -  Turn ignition off. Disconnect brake switch 2-pin harness connector. See Figure. Measure voltage between ground and brake switch harness connector terminal "B" (Green/Yellow wire). If battery voltage is not present, go to next step. If battery voltage is present, repair short circuit to power in Green/Yellow wire between brake switch harness connector terminal "B" and PCM 104-pin harness connector terminal No. 92. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  8.
  3. Inspect Brake Switch Connector For Poor Connection -  Turn ignition off. Disconnect brake switch 2-pin harness connector. Check for poor connection due to damaged, pulled-out terminals, corrosion, etc. If no problems are found, go to next step. If any problems are found, repair as necessary. After repair, go to step  8.
  4. Inspect Brake Switch Power Circuit For Open Circuit -  Measure voltage between ground and brake switch harness connector terminal "A" (Green wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit in Green wire between brake switch harness connector terminal "A" and positive battery terminal. After repair, go to step  8.
  5. Inspect PCM Connector For Poor Connection -  Turn ignition off. Disconnect PCM 104-pin harness connector. Check for poor connection due to damaged, pulled-out terminals, corrosion, etc. If no problems are found, go to next step. If problem is found, repair as necessary. After repair, go to step  8.
  6. Inspect Brake Switch Signal Circuit For Open Circuit -  Reconnect brake switch harness connector. Connect 104-pin Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Turn ignition on, engine off. Measure voltage between ground and breakout box terminal No. 92. If battery voltage is present, go to next step. If battery voltage is not present, repair open circuit in Green/Yellow wire between brake switch harness connector terminal "B" and PCM 104-pin harness connector terminal No. 92. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  7. Inspect Brake Switch -  Disconnect brake switch 2-pin harness connector. Check continuity between brake switch terminals. With brake pedal depressed, continuity should be present. With brake pedal released, continuity should not be present. If brake switch is operating as specified, go to next step. If brake switch is not operating as specified, replace brake switch. After repair, go to next step.
  8. Verify Trouble Shooting Of DTC P0703 Completed -  Reconnect all connectors. Turn ignition on, engine off. Using scan tool, clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Drive vehicle at 18.6 MPH or more. Depress brake pedal more than 10 times, while driving. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0703 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. If same DTC P0703 is not present, go to next step.
  9. 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, follow appropriate DTC diagnostic procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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