SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSMAZDA2006B4000 BASE, AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE SYMPTOM TROUBLESHOOTING - (3 OF 5)DTC APPLICATION CHART - POWERTRAIN CONTROL MODULE (PCM)TRANSMISSION CONTROL SWITCH (TCS) OR TRANSMISSION CONTROL INDICATOR LAMP (TCIL) CIRCUIT MALFUNCTION
2006 Mazda B4000 Base, Automatic

Transmission Control Switch (TCS) Or Transmission Control Indicator Lamp (TCIL) Circuit Malfunction

2006 Mazda B4000 Base, AutomaticSECTION Transmission Control Switch (TCS) Or Transmission Control Indicator Lamp (TCIL) Circuit Malfunction
DTC P1780 DETECTION CONDITION & POSSIBLE CAUSES

DTC P1780 TRANSMISSION CONTROL SWITCH (TCS) OR TRANSMISSION CONTROL INDICATOR LAMP (TCIL) CIRCUIT MALFUNCTION
DETECTION CONDITION 
  • P1780 indicates the TCS was not cycled during KOER self-test.
POSSIBLE CAUSE 
  • Open or short circuit
  • Damaged TCS
  • Damaged powertrain control module (PCM)
  • Damaged indicator bulb and/or fuse
HINT  TCS Description 
  • Momentary contact switch that allows the driver to cancel overdrive gear.
  • When TCS is pressed, a signal is sent to the PCM which then uses the shift solenoids to disengage/disable overdrive gear operation. At the same time, TCIL is illuminated to notify the driver that overdrive gear is canceled. When TCS is pressed again, overdrive gear operation is enabled and the TCIL is turned OFF.
  • Whenever the ignition is cycled off and then on, the TCS is turned off and overdrive gear is enabled, even if the TCS had been on when ignition was shut off.
G04306993Courtesy of MAZDA MOTORS CORP.
DTC P1780 DIAGNOSTIC PROCEDURE

DTC P1780 TRANSMISSION CONTROL SWITCH (TCS) OR TRANSMISSION CONTROL INDICATOR LAMP (TCIL) CIRCUIT MALFUNCTION
STEP INSPECTION ACTION
1
  • Was the PCM quick test performed? 
 Yes Go to next step.
No Perform PCM quick test. See PCM QUICK TEST  .
2 CHECK TEST VALIDITY
  • Key on, engine off (KOEO).
  • Using WDS or equivalent tester, select Diagnostic Data Link.
  • Select PCM.
  • Select PID/Data Monitor and Record.
  • Access the TCS PID.
  • Cycle the TCS switch button, then hold it depressed.
  • Does TCS PID reading switch from ON to OFF, and does reading indicate ON when button is depressed? 
 Yes Rerun KOER self-test to cycle TCS.
No Go to next step.
3 CHECK TRANSMISSION CONTROL SWITCH (TCS) CIRCUIT FOR VOLTAGE
  • Key OFF.
  • Disconnect PCM.
  • Install breakout box, leave PCM disconnected.
  • Key on, engine off (KOEO).
  • Measure voltage between PCM test pin 29 (TCS) and PCM test pins 24 and 77 (PWR GND) while cycling the TCS several times.
  • Does voltage cycle? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Go to step 7.
No Go to next step.
4 CHECK HARNESS CIRCUIT(S) FOR SHORT TO GROUND
  • Key OFF.
  • Disconnect TCS.
  • Measure the resistance between PCM test pin 29 (TCS) and PCM test pins 24 and 77 (PWR GND).
  • Is the resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit.
Go to step 7.
5 CHECK RESISTANCE OF THE TCS HARNESS
  • Measure resistance of TCS circuit between smart junction box fuse 20 (10A) and TCS harness connector.
  • Measure resistance of TCS circuit between PCM test pin 29 and TCS harness connector.
  • Is each resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open circuit.
Go to step 7.
6 CHECK HARNESS CIRCUIT FOR SHORTS TO POWER
  • Measure resistance between PCM test pin 29 (TCS) and PCM test pins 71 and 97 (VPWR).
  • Is the resistance greater than 10K ohms? 
 Yes Replace damaged TCS.
See TRANSMISSION CONTROL SWITCH (TCS) REMOVAL / INSTALLATION .
Go to next step.
No Repair short circuit.
Go to next step.
7 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Connect all disconnected connectors.
  • Clear DTCs from PCM memory using WDS or equivalent tester.
  • Perform PCM quick test.
  • Is same DTC present? 
 Yes Replace PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION .
Repeat PCM quick test.
No In any other DTC is present, go to applicable DTC inspection. See DIAGNOSTIC TROUBLE CODE (DTC) INDEX - POWERTRAIN CONTROL MODULE (PCM) . If no DTC is present, troubleshooting is complete.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.