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Home >> Mazda >> 2007 >> B4000 SE, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (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 2003 Mazda B4000, 2003 Mazda B3000, and 2003 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 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . With KOEO, measure voltage between breakout box terminal No. 29 (TCS circuit) and terminals No. 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. After repair, go to step  7 .
  4. Check Harness Circuit(s) For Short To Ground -  Turn ignition off. Disconnect TCS 2-pin harness connector. Measure resistance between breakout box terminals No. 29 (TCS circuit) and 24 and 77 (PWR GND circuits). If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, 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 (Violet wire) between central junction box fuse panel No. 2 fuse (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 reading is less than 5 ohms, go to next step. If either resistance reading is 5 ohms or more, repair open circuit. After repair, 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 reading is more than 10,000 ohms, replace damaged TCS. After repair, go to next step. If resistance reading is 10,000 ohms or less, repair short circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  7. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Using scan tool, clear DTC from PCM memory. Perform 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 DTC is present, trouble shooting is complete.
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