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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 48 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P1780: Transmission Control Switch Malfunction Or Transmission Control Indicator Light Circuit Malfunction >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
  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

    With KOEO, using scan tool, select Diagnostic Data Link. Select PCM. Select PID/Data Monitor and Record. Access TCS PID. While observing TCS PID, cycle TCS switch button, then hold it depressed. If TCS PID reading switches from on to off, and if reading indicates on when button is depressed, rerun KOER Self-Test to cycle Transmission Control Switch (TCS). If TCS PID reading does not switch from on to off, and/or if reading does not indicate on when button is depressed, go to next step.

  3. Check Transmission Control Switch (TCS) Circuit For Voltage

    Turn ignition off. Disconnect PCM connector. Install breakout box, leaving PCM disconnected. With KOEO, measure voltage between breakout box terminals No. 29 (TCS circuit) and 24 and 77 (PWR GND circuits) while cycling TCS several times. If voltage does not cycle, go to next step. If voltage cycles, replace faulty PCM. Go to step  7 .

  4. Check Harness Circuit(s) For Short To Ground

    Turn ignition off. Disconnect TCS connector. Measure resistance between breakout box terminals No. 29 (TCS circuit) and 24 and 77 (PWR GND circuits). If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short circuit. See WIRING DIAGRAMS article. Go to step  7 .

  5. Check Resistance Of TCS Harness

    Measure resistance of TCS circuit (Tan/White wire) between central junction box fuse panel fuse No. 2 (4.0L is 15-amp, 2.3L and 3.0L is 10-amp) and TCS harness connector. Record reading. Measure resistance of TCS circuit between breakout box terminal No. 29 and TCS harness connector (Tan/White wire). Record reading. If each resistance is less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open circuit. See WIRING DIAGRAMS article. Go to step  7 .

  6. Check Harness Circuit For Shorts To Power

    Measure resistance between breakout box terminals No. 29 (TCS circuit) and 71 and 97 (VPWR circuit). If resistance is more than 10,000 ohms, replace damaged TCS. Go to next step. If resistance is 10,000 ohms or less, repair short circuit. See WIRING DIAGRAMS article. Go to next step.

  7. Verify Trouble Shooting Of DTCs Completed

    Reconnect all electrical connectors. Using scan tool, clear DTC memory. Using scan tool, retrieve DTCs. See QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM and repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTCs are set, trouble shooting is complete.
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