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.
2018 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE
Data Communication Module (DCM)
| Terminal No . | Content | Measuring condition | Standard |
|---|---|---|---|
| A1 | - | - | - |
| A2 | - | - | - |
| A3 | LED GREEN | - | - |
| A4 ←→ Chassis ground | i-button | i-button OFF → ON | 1.6 kΩ or more → less than 1 Ω |
| A5 ←→ Chassis ground | SOS button | SOS button OFF → ON | 1.6 kΩ or more → less than 1 Ω |
| A6 | - | - | - |
| A7 | CAN L | - | - |
| A8 | Ignition power supply | Ignition switch OFF → ON | Less than 1 V → 9 - 16 V |
| A9 | - | - | - |
| A10 | Battery power supply | Always | 9 - 16 V |
| A11 | - | - | - |
| A12 | - | - | - |
| A13 | LED RED | - | - |
| A14 ←→ Chassis ground | GND | Always | Less than 1 Ω |
| A15 | - | - | - |
| A16 | - | - | - |
| A17 | CAN H | - | - |
| A18 | Collision detection signal | - | - |
| A19 | MUTE | - | - |
| A20 ←→ Chassis ground | ACC | Ignition switch OFF → ACC ON | Less than 1 V → 9 - 16 V |
| B1 | Front speaker input LH - | - | - |
| B2 | Front speaker output LH - | - | - |
| B3 | Front speaker input RH - | - | - |
| B4 | Front speaker output RH - | - | - |
| B5 | MIC signal OUT | - | - |
| B6 | MIC signal | - | - |
| B7 | - | - | - |
| B8 | MIC 5 V | - | - |
| B9 | Front speaker input LH + | - | - |
| B10 | Front speaker output LH + | - | - |
| B11 | Front speaker input RH + | - | - |
| B12 | Front speaker output RH + | - | - |
| B13 ←→ Chassis ground | MIC GND OUT | Always | Less than 1 Ω |
| B14 | MIC GND IN | - | - |
| B15 | - | - | - |
| B16 | - | - | - |
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.
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