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.
2020 Subaru BRZ Limited, Automatic TransFACTORY OEM SERVICE PROCEDURE
ECM Terminal Arrangement
- Instrument panel junction block ASSY, main body ECM (Network gateway computer).
- Measure the voltage and resistance between terminals.NOTE: This inspection is performed from the back side of the connector with the connector in a connected state.
Terminal No. (Terminal code) Input/Output Item Measuring condition Criteria 3A-15 ←→chassis ground Input Voltage IG ON 11 to 14V 3A-20 ←→chassis ground Input Voltage IG ON 11 to 14V 3A-27 ←→chassis ground Input Voltage Always 11 to 14V 3C-19 ←→chassis ground Input Voltage Always 11 to 14V 3E-1 ←→chassis ground Input Voltage Always 11 to 14V 3A-12 ←→chassis ground - Resistance Always Less than 1 Ω 3A-13 ←→chassis ground - Resistance Always Less than 1 Ω 3B-18 ←→chassis ground - Resistance Always Less than 1 Ω D6-1 (GND) ←→chassis ground - Resistance Always Less than 1 Ω A73-4 (GND) ←→chassis ground - Resistance Always Less than 1 Ω - Remove the main body ECM (network gateway computer) from the instrument panel junction block ASSY.
- Measure the voltage and resistance between terminals.
Terminal No. (Terminal code) Input/Output Item Measuring condition Criteria MB-1 (BECU) ←→chassis ground Input Voltage Always 11 to 14V MB-8 (IG) ←→chassis ground Input Voltage IG ON 11 to 14V MB-9 (ACC) ←→chassis ground Input Voltage ACC ON 11 to 14V MB-32 (BMPX) ←→chassis ground Input Voltage Always 11 to 14V MB-11 (GND) ←→chassis ground - Resistance Always Less than 1 Ω - Measure the voltage and resistance between terminals.
Factory Service Tools
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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.