Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2005 Mazda 6 L4-2.3LFACTORY OEM SERVICE PROCEDURE
Control Module: Testing and Inspection
TCM INSPECTION [FN4A-EL]
Caution:
^ The TCM terminal voltages vary with changes in measuring and vehicle conditions. Always carry out a total inspection of the input and output systems, and the TCM to determine the cause of trouble. Otherwise, a mis-diagnosis could occur.
1. Measure the voltage at each terminal.
^ If any incorrect voltage is detected, inspect the related system(s), wiring harnesses and connector(s) referring to the Action column in the terminal voltage table.
Terminal Voltage Table (Reference)




Note:
^ Use the ground of terminal 10 and 1P of the TCM when measuring terminal voltage, as an error may occur when connecting the negative circuit tester to ground.
Inspection Using an Oscilloscope (Reference)
VSS signal
TCM terminals

^ 2P (+)-1O
Oscilloscope setting
^ 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
^ Drive the vehicle at approximately 10 km/h (6.2 mph)
Input/turbine speed sensor signal
TCM terminals

^ 2l (+)-1O(-)
Oscilloscope setting
^ 500 mV/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Pressure control solenoid signal
TCM terminals

^ 1 E (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Pressure control solenoid signal
TCM terminals

^ 1G (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid A control
TCM terminals

^ 1A (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid B control
TCM terminals

^ 1B (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid C control
TCM terminals

^ 1C (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Caution:
^ The TCM terminal voltages vary with changes in measuring and vehicle conditions. Always carry out a total inspection of the input and output systems, and the TCM to determine the cause of trouble. Otherwise, a mis-diagnosis could occur.
1. Measure the voltage at each terminal.
^ If any incorrect voltage is detected, inspect the related system(s), wiring harnesses and connector(s) referring to the Action column in the terminal voltage table.
Terminal Voltage Table (Reference)
Note:
^ Use the ground of terminal 10 and 1P of the TCM when measuring terminal voltage, as an error may occur when connecting the negative circuit tester to ground.
Inspection Using an Oscilloscope (Reference)
VSS signal
TCM terminals
^ 2P (+)-1O
Oscilloscope setting
^ 1 V/DIV (Y), 10 ms/DIV (X), DC range
Vehicle condition
^ Drive the vehicle at approximately 10 km/h (6.2 mph)
Input/turbine speed sensor signal
TCM terminals
^ 2l (+)-1O(-)
Oscilloscope setting
^ 500 mV/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Pressure control solenoid signal
TCM terminals
^ 1 E (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Pressure control solenoid signal
TCM terminals
^ 1G (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 1 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid A control
TCM terminals
^ 1A (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid B control
TCM terminals
^ 1B (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Shift solenoid C control
TCM terminals
^ 1C (+)-1P
Oscilloscope setting
^ 5 V/DIV (Y), 5 ms/DIV (X), DC range
Vehicle condition
^ Idle after warm up (engine speed approximately 700 rpm, no load, P/S off, A/C off)
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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