The Stovebolt Site Forums The Parking Lot '60-'66 Trucks T5

I know there has been a lot of help from you guys on this But I have one last problem. Speedo. I have the new electronic one 98% installed but I dont know how it is hooked up to the electronic pickup on the tail shaft. It looks like I only have one wire left for a 2prong male plug. Is one of them ground?? Which one?

Well everything is ready except which wire goes where
I made the leads long enough so I can run them to the cab and try different possibilitys

HELP

I haven't done this, but hear are my thoughts. What year, make, model, is T5 out of, so we can find a wiring diagram.

Larry

Just taking a guess 75-85 Camero but GM
used the same 5 speed in the S10

Glad you said Camaro. I have the wiring diagrams for 82-98. It shows that the "Vehicle Speed Sensor Buffer" has a black/white wire to ground. The other wire goes to the ECM. Does that look right?

Let me know if it isn't I'll look some more.

Larry

Ok that sounds logical, however without the plug( I made one up, I don't know which wire is ground. anyway of telling that except by trial and error? Thanks for this much so far. I am a lot closer than I was before your post.

Looking for paint color for 41 chevy pu dash

I must be missing something?

I googled "gm transmission Vehicle Speed Sensor Buffer", and looked for something that might give me an idea about wiring, unfortunately no solution. I did come to one conclusion, we need more information.

What I did gather was the Vehicle Speed Sensor (VSS) sends a magnetic pulse to the VSS Buffer. The Buffer (yellow box connectors on one side) converts the pulses and sends them to the ECM, and,,. There is an exception, some early(?) speedos connected an optics head (used an LED) and the speedo cable screwed into it. Trial and error with 12v on an LED could blow it. There is a lot of information here;

http://www.jagsthatrun.com/V8-chapters/V8-tpi-Speed-Sensors.pdf

IMO match VSS in tranny (part #, pulses), to VSS Buffer, to "Electric Speedometer ( after market, year, model, etc.) You may want to reverse that since speedo is in. 8-] PM me if you like. 8^)

Larry

Try going to www.s10forum.com , one of the largest S10 websites . Click on " forum " at top of page , then on " general tech " . Go down page to " electrical and lighting " section , then on next page - click on " if you need wiring diagrams " and then it goes to year of vehicle . You should be able to find what you need there - good luck !

Hope so, The trial and error method didn't pan out.
It must be working cuz at 3mph it reads 10mph and at 10mph it reads 140. Efforts to callabrate it was met with failure.

go here for your calibration problem

http://www.tbichips.com/drac/
you will probably have to cut and paste this explains why your speedo reads the way it does

The above link is for 90-95 trucks. The calibration dip switch will not be good enough to correct a 10 to 140 mph error. This is from Jags that run
Quote
There are 4 types of VSS signals required by the ECM:
1. The two-pulse (2000 pulses per mile) square wave (D.C current or direct current) used on all TBI
engines thru 1992, all computer-controlled-carbureted engines, and on 1985-1989 TPI engines.
2. A four-pulse (4000 pulses per mile) sine-wave (A.C. current or alternating current) signal is
required by the 1990-1993 TPI, 1992-1993 LT1 engines, and 1990-1993 Camaro 3.1/3.4 V6
engines.
3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic
transmission, 1994 and newer rear drive cars with the automatic transmission
4. A 17 tooth per driveshaft revolution speed sensor used on 1993-1997 LT1 engines with the Borg-
Warner 6-speed transmission. An 11 tooth reluctor ring is used on 1993 LT1 engines with the
Borg-Warner wide ratio (3.35 First gear) 6-speed transmission.
Unquote

IMO we need to match the VSS to the speedo, and maybe even the VSS Buffer.

Larry

what ever I have a 91 T5 in my truck and it works for me. if you have an electric speedo you need a DRAC unit(VSS Buffer) between your vss(vehicle speed sensor) and your speedo. If you do what the link say and solder a dip switch in the DRAC unit, there is a math formula to calibrate your DRAC unit to work with your VSS and Speedo. If you read the link I gave you it explains what you need to know

give me your rear axle ratio and the circumference of your tire and i will give you the right answer

63360 x Gear Ratio x pulses per revolution of speed sensor [40]
tire rolling circumference in inches x 128000

Gazims' problem is when he is doing 10(?) mph, his speedo shows 140 mph. The best correction you can get with the dip switch is .5. Using .5 means that when he is doing 10 mph the speedo will show 70 mph. The good news is he won't be getting any speeding tickets. 8-)

Larry

my understanding with the DRAC and dip switch was so you could calibrate your speedo with the different tire sizes and rear end gearing , and with all the combinations with the dip switch on that site I can't see how it will only correct by .5. Has he even tried a DRAC with dip switch, at the local pick n pull I pick up a DRAC for $5 and a dip switch for like $1, for $6 it was worth the try

Your correct, but there is a limit to what it can correct. The dip switch on the DRAC can be set to define a 'Multiplier'. The 'Multiplier' table is almost at the bottom of your link . It will easily correct for tire error or a different rear axle ratio. Gazim is off by a factor 14.0 x 10.0 mph = 140 mph. The numbers arn't right, but it's almost like it was expecting a 2 or 4 pulse VSS and got 17 pulses. The factor for a 2 pulse VSS would be 8.5 (17/2), and half that for a 4 pulse. If Gazim was actually doing 16.47 mph (add some fudge factor for tires and rear axle + or - ??) when he was showing 140 mph, that would be close to 8.5. The dip switch is the same equivalent of the little gear drives that went between the speedo gear and speedo cable. I hope that makes sense.

Larry

I have no speedo cable or gear, The tranny came with the mag pickup. I have no buffer, drac. or dip switches. The speedo is a new one from Dolphin that is called the one step. So far that is a lie. Will contact dolphin today to seek their advice too.
Keep the info coming Thanks

LORDY it is done, didn't need anything except about 4 extra buddys and Stovebolt trying to figure it out. Dolphin in their infinate wisdom
Named this product the one step,,Let me tell you it is the 20 step. I know I am old but these instructions are difficult for a computor expert to de-cypher. We tried running up and down the road about 10 times, going thru all the intructions. and getting to a step that didn't appear on the speedo/ Anyway it is in without buying any other parts and according to my gps is right on. Thanks to all that have helped me with this project from the time I bought the transmission til today, Without all your help I would be a babe in the woods.

Special Thanks to Larry.

Glad you got it setup. Can't keep us Stovebolters down. :-]

Larry

I could make some recomendations to their booklet on instalation. I also woudn't describe it as one step.
Thanks again and I will provide drinks and cigars next time you get to MIchigan.