FredJones

Hope someone can help. I have an 89 Formula with a 350TPI & 700R4. It has an electroinc speedo. I want to redo the dash with aftermarket gauges including an electronic speedo. The supplier of the gauages provided a dakota digital SGI-5 converter. My question relates to the wiring of the converter. Can I convert the signal from the VSS buffer or do I need to conver the signal (purple wire) that goes to the VSS buffer?

Any help will be appreciated.

redbird_400

I've been looking for answers for this for 3 Freaking years it seems! lol Looks like you need some tech wire install help. I saw a web page that had pictures of the instalation of the dacoda box. I'll see if I can find you that page. One thing I would worry about if I were you is the speedo sender. I was just looking at www.autometer.com and they say the factory sender wont work with their speedo and you will have to buy their speedo. Apearently it sends a different amount of pulses and that.. thats not easily fixed if you ask me. Well not in my case anyway. You have an 89 so you should have full electric right now. It would only seem right that you will only have to buy the proper speedo sender and the guage. I'm not exactly sure what that bufffer does to the signal. Maybe it just stores the info then releases it to the speedo gauge as the name "buffer" in the computer world does. But who knows.


If anyone knows if you can just purchace the electonic speedo sender and the guage and wire it up and be just fine, go ahead and reply. I tried to call the number on auto meter but I got a whole bunch of confused ppl on the other line, they dont know this stuff.

And Dude! If you should happen to get some spare parts from your speedo I'll by them off you. The way your going it doesnt look like it but hey.. if you find some mechanical stuff you like and you end up scraping the other parts, send them my way and I'll send some $ your way. I think all I need is that sender and the correct speedo gear but ehh.. I'll keep searching in the meanwhile and I'll get that link for ya if I can find it.

redbird_400

not on the dacoda box but it might help someone

http://www.hioutput.com/tech/speedo.html

FredJones

What I have learned so far is that the buffer takes the signal from the VSS (on the tranny) and outputs it to the ECM, speedometer and cruise control. In order to use an aftermarket ELECTRONIC speedo you need to know the pulse rate of the factory and replacement speedos. If the pulse rates are different an adapter like the dakota SGI-5 is needed.

According to one source I can eliminate the buffer and just use the SGI-5 box which has up to 5 outputs. I like this option if it will work because the SGI-5 allows easy modification for different tire sizes and rear gear ratios.

What I still don't know is what is the factory pulse rate and what is the aftermarket pulse rate. Or what wave shape the signal from the buffer to the speedo is.

If you are converting to an electronic speedo from a manual one buy the sending unit and speedo as a matched pair. How you feed the ecm from that point is beyond me but the SGI-5 box may do the trick with its multiple outputs.

redbird_400

What I'm thinking to solve my problem is that I need to just find an 700R4 that came out of a 89 Firebird, take off the rear tail housing shaft with its speedo sender. Now keep in mind the trans and the rear tail housing shaft on my currently is from an 89 Camaro wich originally was using a mechanical speedometer. Both automatic transmissions have to be the same, so if I just pull the part from another 89 bird and swap it onto my trans, bang it will work.

Oh and I did find a web site that said the factory sender was a 2 pulse sender. They say its the only one that goes on these cars.

this one explains the basics of how the electric and mechanical speedos work, in case anyone in interested.

http://www.tpub.com/basae/59.htm

I found this info on this link...

1. The two-pulse (2000 pulses per mile) square wave (D.C. current or direct current) used on all TBI engines through 1992, all computer-controlled-carbureted engines, and on 1985–1989 TPI engines.


http://www.jagsthatrun.com/Pages/Spe...eedometer.html

redbird_400

Dude you can get that box for 79 bucks on this site. Cheapest and only place I've found. I woulnt get one a the dealership lol they might try to take your arm and your leg along with your wallet. lol

http://www.dakotadigital.com/Detail....rtNumber=SGI-5

DOOD! Check out the instructions to the dakota box! It should help lots, just the technical stuff I've been looking for on and off for 2 years. Well.. more off then on.. lol Cool! I'm finally gettting somewhere.

http://www.dakotadigital.com/manuals/SGI-5A.PDF <-- pdf, adobe

FredJones

My SGI-5 box came with the gauges. I have the instructions and the info from JTR. Knowing it is a 2 pulse factory helps since the gauge I am using needs 8 pulses. Getting the box to do the conversion is the hard part. I need instructions for 4 year olds and an answer to my original question which was can I convert the signal from the buffer or do I have to convert the signal from the VSS itself From what I have read in the instructions I am guessing that I need application 6.

redbird_400

they have this formula which says take your actual speed from a radar, devide it by the speedometer reading and refer to the char to tell you which switches need to be on and which need to be off. That was this link, chart is at the bottom.

http://www.dakotadigital.com/manuals/SGI-5A.PDF

Hope you have those traffic deals in the street that tell you how fast your going on some light up sign. There are quite a few of those in dallas.

btw, does your speedo even read? Mine goes from 0-120 when the actual car goes from 0-5mph lol. I think I have a speedo sender that is way off. I mean.. its even off the charts on that site. Since my speedo needs to read 2000ppm and the highest speedo sender sends at 8000ppm thats 6000ppm off by what the reasearh shows, so if I were going 5mph and and my speedo read 120 then imagine the ppm that this thing in my car is sending out! lol Its got to be waayy over 8000 as it seems to me, maybe add another zero as it might be 80000 ppm lol. I had a trans shop put that sender in there. I wish I knew the specs on it, I wish I did.. I'm not even sure if its for my car! The original one was 3 times smaller.

FredJones

My speedo isn't wired yet. I was looking for an answer to which wire to use. The one from the ECM or the one from the VSS. If I use the VSS how do I send the signal back to the ECM? If I wire this wrong there is the possibility to blow the ecm. Not what I want to have happen at this point. Especially after dropping the coin for the gauges.

redbird_400

From what I'm getting on this web page and from what makes sence to me, you would need to spice the box on the wire that goes to either your either speedometer, ecm, or the buffer. My car is an 89, the same as yours and from the sender mine goes to the buffer as it seems. Two ppl can figure this out though, have someone reach under the driver side and unplug the sender, have another whatch the buffer box, pull on the wire and see if it pulls on the buffer box, it should. This site says that you need to spice into it before it gets to the buffer, or anything else for that matter. It must convert the singlal before you car's computer gets to it basically.

So on which wires, this is from their web page. If it doesnt work and frys your ecm then I would hold them responcible for its their product and their instructions.

This is from their dirrections..

"These speed sensors have a two-pin connectior that plugs into the transmission or transfer case. One of the wires will be ground and the other will be the signal wire. The wires will usually go up and under the dash into the speedometer, vehicle speed buffer, or engine/transmission computer. The signal wire will need to be cut on the SGI-5 can recalibrate it. The sensor side of the wire will go to the SIG IN terminal. The speedometer or buffer side will go to the OUT1 terminal. If the speedometer does not operate correctly after installation of the SGI-5 you may need to switch to OUT2 instead of OUT1. Connect the PWR terminal to a 12-volt accesory wire and conect the GND terminal to a good ground location. Begine with thee switches as follows and then Determine how far off the calibration is."

1 off, 2off,3on,4on,5on,6on,7on,8on,9on,10on

FredJones

I got an answer fom Dakota Digital. According to them I can use ether the wire from the buffer (option 6) or the wire from the VSS (option 3). My wiring harness is out of the car (easier to custom make a dash that way) so not a problem tapping into the wires. The one from the buffer is green with a black stripe the ones from the VSS are purple and yellow. The purple and yellow go from the tranny up into the main engine harness and then enter the body harness through the big connecto in the firewall. After that they go all the way accross the car to the passenger side where the buffer is. From the buffer the green & black stripe wire runs back to the dash where the gauges plug into the main dash. I have had this thing all over my basement floor for a month now and can finally put it back in the car

redbird_400

lol thats cool man, let us know how it turns out after you hook it all up.