2018 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE

Electrical Specification

G12452027Courtesy of SUBARU OF AMERICA, INC.
Terminal No. Content Measuring condition Standard
1 ↔ Chassis ground Security indicator Security indicator light off β†’ on 0 V β†’ 10 - 14 V
2 ↔ Chassis ground Charge warning light Charge warning light off β†’ on 0 V β†’ 10 - 14 V
3 ↔ Chassis ground Oil pressure warning light Oil pressure warning light off β†’ on 0 V β†’ 10 - 14 V
4 ↔ Chassis ground RH turn indicator RH turn indicator off β†’ on 0 V β†’ 10 - 14 V
5 ↔ Chassis ground - - -
6 ↔ Chassis ground LH turn indicator LH turn indicator off β†’ on 0 V β†’ 10 - 14 V
7 ↔ Chassis ground - - -
8 ↔ Chassis ground Auto headlight beam leveler warning light Auto headlight beam leveler warning light off β†’ on 0 V β†’ 10 - 14 V
9 - - -
10 - - -
11 - - -
12 - - -
13 - - -
14 - - -
15 ↔ Chassis ground Driver's seat belt switch Driver's seat belt switch ON Less than 1 Ξ©
16 ↔ Chassis ground Passenger's seat belt switch Passenger's seat belt switch ON Less than 1 Ξ©
17 - - -
18 - - -
19 - - -
20 ↔ Chassis ground Ignition power supply IG OFF β†’ ON 0 V β†’ 10 - 14 V
21 ↔ Chassis ground Washer fluid level sensor - -
22 - - -
23 ↔ Chassis ground Brake fluid level switch Brake fluid level switch OFF β†’ ON 1 MΞ© or more β†’ less than 1 Ξ©
24 ↔ 34 R. DIFF oil temperature sensor - -
25 ↔ 37 Fuel level sensor Always 10 - 600 Ξ©
26 ↔ 35 SI-DRIVE input (engine type: EJ) SI-DRIVE switch OFF β†’ ON 1 MΞ© or more β†’ less than 1 Ξ©
27 ↔ 36 Ambient sensor Always 1 - 35 kΞ©
28 ↔ Chassis ground UART (MFD) Cannot be measured -
29↔ Chassis ground STEERING + i/SET, , switch OFF β†’ ON 1 MΞ© or more β†’ less than 1 Ξ©
30 - - -
31 ↔ Chassis ground SI-DRIVE input (engine type: FA) SI-DRIVE switch OFF β†’ ON 1 MΞ© or more β†’ less than 1 Ξ©
32 ↔ Chassis ground CAN communication line (-) Cannot be measured -
33 ↔ Chassis ground CAN communication line (+) Cannot be measured -
34 R. DIFF GND - -
35 SI-DRIVE input GND (engine type: EJ) - -
36 Ambient sensor GND - -
37 Fuel level sensor GND - -
38 ↔ Chassis ground GND Always Less than 1 Ξ©
39 ↔ Chassis ground Backup ignition power supply IG OFF β†’ ON 0 V β†’ 10 - 14 V
40 ↔ Chassis ground Battery power supply Always 10 - 14 V
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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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