I am having such a hard time with this Dakota Digital SGI-5C, I want to smash it.

I have a wildly bouncing speedo needle at idle but off idle it works fine and is accurate...I have tried the following to fix the bouncing needle:

1. run clean power from the battery to the SGI-5C
2. run clean ground from SGI-5C to back of cylinder head
3. run 10k or 47k ohm pull down or pull up resistors on signal wire
4. run external 5v regulator inline w/ power lead
5. make new VSS harness with wires twisted tightly and run away from ignition sources

NONE of the above helped...I am so mad I'd return it but then I'm back to having a speedo off 15 mph

Here's the weird thing. If I unplug the VSS I still get the bouncing needle at idle. I wonder if I have a defective SGI-5C.....

 

Mine will do that to sometimes. If you find the problem let us know.

 

 

^tried that, did not fix it, and it made the speedo not come online until 10 mph.

I am talking at length with Dakota Digital's tech support and I have to give them credit, they are very responsive and have given me several options to try, and have offered to replace the unit free of cost if none of the options work. I am very pleased that they are willing to help me out. I will report back if I ever fix this.

 

Where do you get this dash and how much is it... I'm interested...

 

We are discussing a universal pulse ratio converter, the SGI-5. I bought it from Summit. It's not a dash, it's just a device for correcting VSS pulses for different axle ratios.

 

Thought that was used to adapt a forth Gen rear to a third gen speedo due yo the difference in CSS pulse data. Didn't know it was based off of axle ratio...

 

It's for pulse type and ratio conversion, it can be used for a lot of purposes.

 

Ah cool thanks for the info... are you running it through your vss buffer or just ecm. It may be necessary to tune the ecm if that's what buffers the signal..

 

The ECM does not buffer the signal in an 89, it has an external buffer, and yes I am running through the buffer still. In theory it should work (well, off idle, it does) but Dakota Digital may have me try eliminating the buffer and letting their box do all the buffering. I don't really care how I do it as long as it works, but they are checking first to make sure we can pull two 2000 ppm outputs and one 4000 ppm output off their box so I won't lose cruise if we go that route.

This is all to correct the speedo for the 3.73s I installed...sigh!

 

I hear ya man... my speedometer doesn't currently work at all. I've changed the gauge and vss to no avail. Checked all my wiring as well which is good and my ecm buffers the signal in my 91.

 

Just to provide some closure to this old thread I started, I never got the Dakota Digital SGI-5c converter box to work with the 1989 trans am speedo without a wildly bouncing needle at idle. I tried all of what I listed in my first post to cure the bouncing needle but nothing fixed it. I ended up selling the car (not for that reason but the bouncing speedo certainly did not make me happy) so there is someone else driving a really mint condition 89 trans am around with a bouncing speedo needle somewhere. I am currently working on a different project that is probably going to require one of these speedo converter boxes and I am really dreading having to use one after this past ordeal.

 

I know this is an older thread, but I wanted to contribute my findings with the exact same issue I've had with my SGI-5 box for several years, in two different vehicles.

I realized that when the speedometer bounced, if I changed the load on the electrical system (hit the brakes, for example) the needle would drop to zero, at least for a moment. It seemed that I was getting interference from the power side of the system. I tried powering the box from several different circuits in the car, all with the same results.

Finally, I ran a power wire directly to the battery and that seems to have cured the issue!

The box only draws .01 amps of current, so it shouldn't be an issue to have it powered all the time, but if it does cause a problem I will try using a relay to power it only when the key is on.

Hope this helps someone else with this VERY annoying issue!!


-Paul