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.
2021 Subaru Forester BaseFACTORY OEM SERVICE PROCEDURE
Electrical Specification
| Terminal No. | Contents | Measuring condition | Standard |
|---|---|---|---|
| (i10) No. 1 (+) β β Chassis ground (-) | Battery power supply | Always | 8 V - 16 V |
| (i10) No. 2 (+) β β Chassis ground (-) | Ignition power supply (main) | Ignition switch ON | 8 V - 16 V |
| (i10) No. 3 | - | - | Β |
| (i10) No. 4 (+) β β Chassis ground (-) | Seat belt (driver's seat) | Seat belt not fastened - fastened | 8 V - 16 V - 0 V |
| (i10) No. 5 | - | - | - |
| (i10) No. 6 | CAN H (CAN communication line) | - | - |
| (i10) No. 7 | CAN L (CAN communication line) | - | - |
| (i10) No. 8 | Seat belt (rear right) | Seat belt not fastened - fastened | 8 V - 16 V - 0 V |
| (i10) No. 9 | Seat belt (rear center) | Seat belt not fastened - fastened | 8 V - 16 V - 0 V |
| (i10) No. 10 | Seat belt (rear left) | Seat belt not fastened - fastened | 8 V - 16 V - 0 V |
| (i10) No. 11 | MFD (UART communication line) | - | - |
| (i10) No. 12 | WARNING BOX (UART communication line) | - | - |
| (i10) No. 13 | - | - | Β |
| (i10) No. 14 (+) β β Chassis ground (-) | Washer fluid level sensor | Washer fluid level sensor OFF - ON | 8 - 16 V - 0 V |
| (i10) No. 15 | - | - | - |
| (i10) No. 16 | - | - | Β |
| (i10) No. 17 | - | - | Β |
| (i10) No. 18 (+) β β Chassis ground (-) | Oil pressure warning light | Oil pressure sensor OFF β ON | 8 - 16 V - 0 V |
| (i10) No. 19 (+) β β Chassis ground (-) | Security indicator | - | - |
| (i10) No. 20 | - | - | - |
| (i10) No. 21 | RH turn indicator | Switch ON | 0 V - 8 - 16 V |
| (i10) No. 22 | LH turn indicator | Switch ON | 0 V - 8 - 16 V |
| (i10) No. 23 | Ambient sensor (+) | Always | Ref. to AIR CONDITIONERS>AMBIENT SENSOR>INSPECTION . |
| (i10) No. 24 | Ambient sensor (-) | - | - |
| (i10) No. 25 | Fuel level sensor (+) | Always | Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL LEVEL SENSOR
. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL SUB LEVEL SENSOR . |
| (i10) No. 26 | Fuel level sensor (-) | - | - |
| (i10) No. 27 | Shift position information (UART communication line) | - | - |
| (i10) No. 28 | - | - | - |
| (i10) No. 29 | Illumination control switch (GND) | - | - |
| (i10) No. 30 | Illumination control switch (VR) | - | - |
| (i10) No. 31 | Illumination control switch (+) | - | - |
| (i10) No. 32 β β No. 29 | Bright switch signal input | Switch ON | Continuity exists |
| (i10) No. 33 | Bright switch signal output | - | - |
| (i10) No. 34 | Illumi. (-) PWM | - | - |
| (i10) No. 35 | SI-DRIVE switch | - | - |
| (i10) No. 36 β β Chassis ground | Auto Start Stop OFF switch | Switch ON | Continuity exists |
| (i10) No. 37 β β Chassis ground | X mode switch | Switch ON | Continuity exists |
| (i10) No. 38 β β Chassis ground | TFT switch (TFT color meter only) | Switch ON | Continuity exists |
| (i10) No. 39 | - | - | - |
| (i10) No. 40 β β Chassis ground | GND | Always | Less than 1 Ξ© |
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:
- 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.