OBD II Pin Configuration

[How-To Doc]

OBD II Pin Configuration

by b3lha

I've been trying to relate the Subaru OBD2 wiring to the OBD2 standard and I just discovered something.

The OBD2 standard illustrates the plug with the wide edge uppermost.


\ 01 02 03 04 05 06 07 08 /
\ 09 10 11 12 13 14 15 16 /

But the Subaru wiring diagrams illustrate it with the narrow edge uppermost.

/ 01 02 03 04 05 06 07 08 \
/ 09 10 11 12 13 14 15 16 \

This means that the pin numbers are backwards on the Subaru diagrams. Pin 1 in the OBD2 standard is pin 16 on the Subaru pinout. Pin 2 is pin 15 and so on.

The subaru wiring diagrams shows:

Pin 01 connected to Power
Pin 04 connected to the ECU
Pin 05 connected to the ECU
Pin 10 connected to the ECU
Pin 12 connected to Ground
Pin 13 connected to Ground

When you renumber the pins correctly, the wiring matches the standard:

Pin 01 (=16) is Battery power
Pin 04 (=13) is Manufacturer specific (SSM RX)
Pin 05 (=12) is Manufacturer specific (SSM TX)
Pin 10 (=07) is ISO 9141 K-Line
Pin 12 (=05) is Signal Ground
Pin 13 (=04) is Chassis Ground
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