My project:

Create my own OBD2 splitter and extend an OBD2 cable with ONLY the required wires under my van to the front-dash.

 

Background:

My '86 VW van has a 2001 Subaru Legacy engine in it, but the engine bay is in the rear of the van. I want to run "required" OBD2 wires up front and make an OBD2 diagnostic port available in the van's dash area. Yes, I know Bluetooth exists, but I want a mechanic to be able to use their preferred scantool under the dash while test driving it, so I am running wires from back to front regardless of this fancy, Bluetooth technology.

 

Problem

I look at the 2001 Subaru OBD2 connector and it has 8 wires connected to it.

I went to the scrap yard and pulled two more Diagnostic Ports w/ OBD2 connectors for my project and I see 7 wires connected to the OBD2 connectors! What? These 7 pin connectors were pulled from a 2001 and 2003. To make matters more confusing, I have a friend with a later model VW/Subaru conversion with drive-by-wire (2011) that only has 3 wires connected on his custom OBD2 port for his VW van project (note: "custom", not stock)...

 

Why are they different?

What pins in my OBD2 do I really need to wire up on my project? I don't want to split & run 8 wires up front, if I only need 3...

 

Jason

Edited February 26, 201412 yr by coclimber

2001 Subaru ECU just uses one wire for data to the OBD II port.  Purple I believe.

 

One red wire for 12v+ and 2 Black/reds for ground.

 

So yeah,,, it could be 3 or 4 wires (2 grounds...redundant)

 

The extra wires in the connector are for line end checking and ABS Data.

 

 

Here's the pin out I found online. It only shows 7, which would make sense about the two others I pulled from the junkyard. But, I am clueless as to why my van's 2001 Legacy OBD2 female connector has 8... Looks like pin 16 is the batter power you speak of. Need that! Which others do you think now?

Edited February 26, 201412 yr by coclimber

Well, that diagrahm above has the pin numbers flipped from what subaru calls them.......top is the bottom and order reversed.

 

 

You need a Purple(Violet)/green wire from the ECU pin d16 to be connected to pin 10  (7 in your diagrahm)

 

Then you need ground to pins 12 and 13  (4 and 5 in your diagrahm)

 

And of course 12v to pin 1 (16 in your diagrahm)

Huh.. So, you say these #s are all backwards!    

 

I've noticed the pin outs on some documentation gets "flipped" depending on if you are looking at the female or male connector.  But, either way, if the documentation on the pin out references the correct #, it wouldn't matter, I could just read it L to R or R to Left.  Oh well!  Let me take a look-see a little closer!

Gloyale: can you point me to where the OEM Subaru OBD2 diagram is, so I can cross-reference them myself?  That would be much appreciated.

 

Jason

Gloyale: can you point me to where the OEM Subaru OBD2 diagram is, so I can cross-reference them myself?  That would be much appreciated.

 

Jason

 

Well....I can't remember were I found it...It's a Zipped pdf of the entire FSM.