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.
Communication For Initializing Impossible
Diagnosis:
Defective harness connector
Trouble symptom:
Subaru Select Monitor communication failure
Wiring diagram:
CVT control system Ref. to WIRING SYSTEM (IMPREZA MODEL)>CVT CONTROL SYSTEM .
Use the check board when measuring the TCM terminal voltage and resistance.
- CHECK IGNITION SWITCH
.
Is the ignition switch ON?
Yes: Go to 2.
No: Turn the ignition switch to ON, and select the [Transmission] using the Subaru Select Monitor.
- CHECK BATTERY
.
- Turn the ignition switch to OFF.
- Measure the battery voltage.
Is the voltage 11 V or more?
Yes: Go to 3.
No: Charge or replace the battery.
- CHECK BATTERY TERMINAL
.
Is there poor contact at battery terminal?
Yes: Replace or tighten the battery terminal.
No: Go to 4.
- CHECK INSTALLATION OF TCM CONNECTOR
.
Turn the ignition switch to OFF.
Is the TCM connector inserted into the TCM until the clamp locks?
Yes: Go to 5.
No: Insert the TCM connector to TCM.
- CHECK LAN SYSTEM
.
Perform the diagnosis for LAN system using the Subaru Select Monitor. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE .
Is DTC of CAN communication displayed?
Yes: Perform the diagnosis according to the DTC. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .
No: Go to 6.
- CHECK SUBARU SELECT MONITOR COMMUNICATION
.
- Turn the ignition switch to ON.
- Check whether communication to transmission system can be executed normally.
Is the [Select Function] screen displayed?
Yes: Check DTC of TCM. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DIAGNOSTIC TROUBLE CODE (DTC) .
No: Go to 7.
- CHECK POWER SUPPLY CIRCUIT
.
- Turn the ignition switch to OFF.
- Disconnect the TCM connector.
- Turn the ignition switch to ON. (Engine OFF)
- Measure the ignition power supply voltage between TCM connector and chassis ground.
Connector & terminal
(T10) No. 8 (+) - Chassis ground (-):
(T10) No. 24 (+) - Chassis ground (-):
(T10) No. 34 (+) - Chassis ground (-):
(T10) No. 40 (+) - Chassis ground (-):
(T10) No. 41 (+) - Chassis ground (-):
Is the voltage 10 - 13 V?
Yes: Go to 8.
No: Repair the open circuit of harness between TCM and battery.
- CHECK HARNESS CONNECTOR BETWEEN TCM AND CHASSIS GROUND
.
- Turn the ignition switch to OFF.
- Measure the resistance of harness between TCM connector and chassis ground.
Connector & terminal
(T10) No. 26 - Chassis ground:
(T10) No. 42 - Chassis ground:
Is the resistance less than 10 Ω?
Yes: Go to 9.
No: Repair the open circuit of the TCM ground circuit and poor contact of connector.
- CHECK POOR CONTACT OF CONNECTOR
.
Is there poor contact of control module power supply, ground circuit and data link connector?
Yes: Repair the connector.
No: Check the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>TRANSMISSION CONTROL MODULE (TCM) .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.