So.... I have the swap all done and have the SGI-5 box installed but have no Speedo.....

Here is how I had it wired:

The car's existing VSS has one black wire and one Pink with black stripe wire. I removed the factory 3rd gen VSS harness and spliced in a 4th gen VSS harness and the SGI-5 box as follows:

Power socket on box: Power from Accessory
Ground socket on box: Ground to chassis
SPD-IN socket on box: from VSS
OUT4: Pink wire with black stripe from car
Black wire from car: Tapped into other wire from VSS

With that setup I had a speedo that would go from 0-140 in about a tenth of a second when I would start moving.

So I started moving wires around (tried all of the outputs, switched which wire went where from the VSS, tried grounding one of the VSS wires independently from the box and in the same socket as the box, tried using the black wire from the car as the output wire from the box, and played with the DIP switches) but never got any kind of movement out of the speedo itself with any of the other setups I tried....

So can some of you guys that have gotten it successfully installed in an application similar to mine give me some insight on this? I mean like exactly what you did with the car's wiring and the wiring for the box. I did some searching but nobody has laid it out completely in detail as far as I could tell.....

Mucho thanks in advance for your help!!!!!

 

Use output 3 and make sure to ground the other wire from the tranny side of the VSS.

Then use the formula to correct your MPH using the DIP switches.

 

Hmmm... While I am fairly certain I tried that setup to no avail, I am going to give it a try again and see what happens. Thanks.

 

Well, I tried that setup and I have no movement at all from the speedo..... I also tried all of the different ways with the black wire coming from the car's VSS harness grounded and not grounded and still got nothing.

This is about as frustrating as it gets .....

I am beginning to think that I got a bad box

Anybody else have any ideas?????

 

I figured the VSS on the T56 was fine but I decided to throw the DVOM on it and check it and it does indeed have proper output (starts around 1v AC and goes up as the speed increases.). Still no Speedo movement at all...............

 

Ya know, I had a similar problem. Went off the schematics in my Helm manual, wired up the wire it said was the VSS input, GOT NOTHING! So I went back, after much head scratching, and flipped the wires heading to the ECM. Presto, worked perfect. Not sure what the wire colors were though, and my car isn't here for me to check. Hope ya get it worked out.

 

So did you ground the other wire from the car's harness that was not getting the signal from the SGI-5 box or did you leave it hanging, or ???

It looks to me that the ground side wire of the car's harness shouldn't matter and could be left hanging (so-to-speak), but I am pretty much throwing common sense out the window since I tried using that the first few times and it got me nowhere .

Thanks again.

 

K, I got it.... Finally!!!!

So, for the purpose of those that do searches in the future, here is how it all worked out:

SGI-5 box:
Power for box: Accessory circuit of car
Ground for box: Chassis
Speed signal in: Fed from 4th gen VSS (see below for details)
Output from box: Output 3

Car's harness:
Black wire: to ECM (not changed) from Output 3 of box
Pink with black stripe wire: Not connected to anything

4th gen VSS harness:
One wire: To speed signal in of box
Other wire: To ground terminal of box (recommeded by Dakota to minimize interference but could be grounded to chassis theoretically).
Does not matter which wire goes where as the sensor is an AC signal generator.

So there it is all nice and laid out for ya'll .

I think I had it wired that way at one point before, but I am guessing that I had a bad connection or something.

Now to set the DIP switches for the proper speedo calibration!

 

the pink w/ black stripe wire on the car is a 12V+ in run.

 

Quote:

So, for the purpose of those that do searches in the future, here is how it all worked out:

The wires from the VSS to the ECM on my 91 Z were different colors, so here's how mine wired up:

Car's harness:
Yellow wire: to ECM (not changed) from Output 3 of box
Purple wire: Not connected to anything