Speedo Correction VR with '424" ecu

Wiring diagrams and questions
Post Reply
IMA355-2
Posts: 41
Joined: Sat Jun 18, 2016 3:32 pm
cars: VR SS T56 6 Speed 3.9 diff

Speedo Correction VR with '424" ecu

Post by IMA355-2 »

Hi Guys

thought I would do a quick write up on correcting the speedo in my VR SS.
The vehicle has a T56 in it aswell as 3.9 diff gears so my speedo was reading about half of what I was actually travelling. (40T reluctor on Auto vs 17T on T56)
It just so happened that the guy I purchased all the stuff off to convert my car to the 6spd manual included a Dakota digital SGI-5 C.

So there are 2 wires from the ECU to the speed sensor. one is a Tan wire and is Speed sensor Low into the ECU. the other wire is a Blue/White wire and that is Speed Sensor High Into the ECU. You only need to cut the Blue/white wire.
If you wire the corrector into the tan wire you will still get your normal speedo reading but you will not be able to calibrate/correct it as it is before the speed sensor!

I ran a 2 Core shielded cable (good quality stuff from jaycar) from the glove box to underneath the car (i drilled a hole in the floorplate where the shifter comes up)
My wires were blue and white in the 2 core cable.
After cutting the blue\white wire, i then soldered my white wire to the speed sensor. This connects to the sig. input in the Dakota digital.
My Blue wire soldered to the blue\white wire that goes to the ecu. This is connected to the output 1 on Dakota digital.
From there you need to find a switched power source and earth ( i used the cig lighter plug.)

To test that its all working jack the back of the car up and put it on stands. start vehicle and engage a gear to see if the speedo is working.
if you what speed your car travels in a certain gear at what revs you can do a rough calibration while your doing this.

Some people have had issues with the speedo jumping around after installing a speedo corrector between the sensor and the ECU like i have. I seem to have avoided this by using a good quality shielded cable and also soldering and heat shrinking the wires together rather than using cheap crimp connectors.

This corrected both the speed that the ECU sees and also the Speedo calibration. Validated with tuner pro and a gps :)

If you are using a SGI-5 C there are 4 switches. 1\2\3 are off and 4 on was the setting that worked for me using output 1. you do not need to use the speed sensor ground
Attachments
IMG_1921.JPG
Dylan
Posts: 3355
Joined: Mon Aug 02, 2010 6:35 pm
cars: VR Commodore V8

Re: Speedo Correction VR with '424" ecu

Post by Dylan »

It's always good to have a win. Good stuff
User avatar
Gareth
Posts: 2505
Joined: Fri Mar 14, 2014 8:37 pm
Location: Bacchus Marsh, Vic

Re: Speedo Correction VR with '424" ecu

Post by Gareth »

Thanks for sharing that info :thumbup:
According to chemistry, alcohol is a solution...
Post Reply