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Discussion Starter #1 (Edited)
Recently finished this setup on my own car, and wanted to share.

Two reasons to do this -

06+(?) Cars use ABS wheel speed to run the speedo. So those transmissions dont have the speedo wheel in them to run a normal vss. It's possible to install the speedo wheel, but I chose not to. I have an 08 WRX 5mt in a 2000 L.

Reason 2 would be stripped speedo gear. These can break inside the trans and maybe you dont want to fix it proper.

This guide uses Dakota Digital's universal speedo interface found here

Universal Speedometer Signal Interface

Roughly $80 as of 2014.



This can be done with or WITHOUT ABS. In my case my car doesn't have ABS, so I had to install an ABS knuckle, axle and sensor.

Only downside I had found is that this system doesn't work until about 10mph. This is due to the ABS wheel speed sensor. It's probably possible to fix this, but I haven't attempted yet. I may need to do this in the future due to launch control.

The nice thing is that it is adjustable, so you can dial in perfect speed reading with a GPS.



Anyway this is very very simple wiring to do..

Shielded wiring is recommended. The ABS signal is shielded from factory, unsure about VSS. Since you will be adding more length and running it through random areas it's best to go shielded. Ground 1 side of shield and leave the other end unhooked.


There are 3 connection points

At the ABS wheel sensor there are 2 wires, black and white. Tap both of these and extend them to the DD unit. Note that the actual harness wires may be a different color, but on the sensor side (before connector) they are all white and black.

2nd connection is at the vss. Im talking about an electronic vss, obviously cable style would be different so you're on your own.

There's 3 wires, power ground and signal. The VSS has a short jumper harness from sensor to bulkhead, so I decided to cut it up there to leave connectors on it.



middle wire is gound, and the grn/blk wire is signal.

The signal wire will go to 135-pin 24 on the ecu. So you can verify connectivity to that pin with a continuity tester or multimeter and you're good. It also goes to the cluster, but you don't have to worry about that. If the ecu gets the signal, the cluster will too.


Our 3rd and final connection point is at the actual DD unit. You can mount yours wherever, I choose to mount mine here:



The lower dash still fits over it just fine, and it's accessible through the fuse box hole.

The connections here are as follows:




Power and ground you will supply. Switched power. I tapped into the radio power and grounds.

Sensor ground is black wire from ABS sensor, and ground from VSS (middle wire)

Input is white wire from ABS sensor.

Output #5 is signal wire from VSS harness (goes to ECU and cluster)


That's it for wiring! Set all your dip switches to OFF. Start driving and your speedo should read very high. Hold the Down button on the DD unit to calibrate to proper speed with GPS.

When I calibrated mine I had the car up on jacks, I let the car idle in 4th gear and then set the speedo to the proper speed. Then I dialed it in on the road with a GPS.



So that's it. It's very simple, I think even for people scared of wiring. DCCDPro is now making a similar unit, but their's is about $200. But if you had DCCD you would have to go that route I believe.


I hope this helps someone, someday. Cheers!
 

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nice work.
my only suggestion would be to shield the vss wire. you will see this on early subarus. although, I assume the dakota unit would be well off without
 

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Discussion Starter #3
nice work.
my only suggestion would be to shield the vss wire. you will see this on early subarus. although, I assume the dakota unit would be well off without
Thanks! I added shielded wiring recommended. I did use shielded, but it's hard to see because my phone takes poor pics in the dark. I think it's important if you are adding a lot of wire to a circuit.
 

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Hi I have just had a legacy Sti 6 speed gearbox fitted in to my 2006 hawkeye Impreza wrx and have an issue that the gearbox has no speedo connector therefore putting my car into limp mode with what seems to be a fuel cutoff at 3500 rpm is there anyway around this ?
 

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Hey! Not to revive an old post, but

I can totally verify this works with existing abs speed sensor. Dakota Digital only sells the SGI-100bt now, but it is the same as the SGI-5e with a few more features.

As of Aug 2020 it costs $100 plus shipping.

The installation and wiring are EXACTLY the same as posted above.

I converted my 04 Forester with 5mt transmission to 08 5mt from a legacy. Bolted right up, minus no geared speed sensor on the transmission.

The 100bt solved my vss issue entirely,

The only difference was for calibration I used the Bluetooth app from Dakota digital and calibration took place with my cellphones GPS in the app.

Mad respect and thanks to tzedek. Great write up bro.
 
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