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Home › Mazda › 2003 › Tribute DX, FWD › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P1780: Transaxle Control Switch - Malfunction › Diagnostic Procedures

Diagnostic Procedures

  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
  2. Check Test Validity -  Turn ignition on, engine off. Using scan tool, select DIAGNOSTIC DATA LINK. Select PCM. Select PID/DATA MONITOR AND RECORD. Access the TCS PID. Cycle TCS switch button, then hold it depressed. If TCS PID reading does not switch from ON to OFF and reading does not indicate ON when button is depressed, go to next step. If TCS PID reading switches from ON to OFF, and if reading indicates ON when button is depressed, rerun KOER Self-Test to cycle TCS.
  3. Check Transaxle Control Switch (TCS) Circuit For Voltage -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. Turn ignition on, engine off. Measure voltage between breakout box terminal No. 29 (TCS) and terminals No. 24 and 103 (PWR GND) while cycling TCS several times. If voltage reading does not cycle, go to next step. If voltage reading cycles, replace PCM. After repair, go to step  7.
  4. Check Harness Circuit(s) For Short To Ground -  Turn ignition off. Disconnect TCS. Measure resistance between breakout box terminal No. 29 (TCS) and terminals No. 24 and 103 (PWR GND). If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is not as specified, repair short circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  7.
  5. Check Resistance Of TCS Harness -  Measure resistance of TCS circuit between I/P fuse panel No. 16 fuse (10-amp) and Brake Shift Interlock 8-pin harness connector terminal No. 4 (Red/Yellow wire). See Fig 1. Measure resistance of TCS circuit between breakout box terminal No. 29 and Brake Shift Interlock 8-pin harness connector terminal No. 1 (Orange/Yellow wire). If each resistance reading is less than 5 ohms, go to next step. If each resistance reading is not as specified, repair open circuit in suspect wire. After repair, go to step  7.
    Fig 1: Identifying Brake Shift Interlock 8-Pin Harness Connector & Terminals
    G00193647Courtesy of MAZDA MOTORS CORP.
  6. Check Harness Circuit For Shorts To Power -  Measure resistance between breakout box terminal No. 29 (TCS) and terminals No. 71 and 97 (VPWR). If resistance reading is less than 10,000 ohms, repair short circuit in harness. After repair, go to next step. If resistance reading is not as specified, replace PCM. After repair, go to next step.
  7. Verify Trouble Shooting Of DTCs Completed -  Reconnect all disconnected connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is not present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, trouble shooting is complete.
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