I finally wired up the Dakota SGI-5C converter to my 88 GTA for the speedo after nearly two years of no speedo. I don't drive the car daily. So it wasn't a big deal. However, I'm looking at selling it. So naturally, it needed to be fixed. Anyway, I wired it up like Clowny's video said. I got it working, but it is around 5-8 MPH maybe 10 off. I'm doing 40 and the speedo reads 35 or so.

Can I get the speedo right by holding the up or down button while driving? I'd obviously need a buddy and a GPS speedo in the front seat.

Also the check engine light for the speedo keeps coming on despite the speedo working. Is this because of how I wired it in, by ditching the buffer box?

 

The buffer box feeds the ECM and the gauges separately on an '88. If you used the SGI-5C to receive input from the trans. and provide output to the buffer, you'd probably not have the SES light.

 

Ok so due to not using the buffer the ses light is on. Ok gotcha. Clowny didn't use the buffer so in turn neither did I.

Now what about the dial in? I should be able to dial in a 10 mph differential between real speed and the speedo using the up/down buttons on the sgi 5 box correct? I have it working just want to confirm if my thinking is correct regarding the calibration.

Thanks

 

Ok I played with the calibration. I am getting confused counting flashes. It seems every time I go to check the calibration it reverts to 15/15. Why would it revert? I got within 3 mph of dead accurate with the car faster than the speedo. The equation gets me mixed up too. I guessing it is supposed to be 12/12. I think I had it at the 3 mph differential at 11/12. Course and fine settings. Anyone with a tpi who can tell me what their settings are? I am using the X 1.00 preset. .5 reads exactly half. I gave up for today after getting back to the 7-8 mph starting point. A friend and I tried adjusting the speedo while driving but it didnt seem to change at all. Did we do something wrong?

 

After trying to figure this out tired and misreading the manual.... I got this figured out. The math told me to use 1.216. I was too tired to realize the number worked with the chart if I turned dip switch 4 on. Set it to 3 coarse and 12 fine it was dead on accurate. Now if only I could eliminate the ses light.