Does anyone know if it's possible to pull a speedometer from a TBI Blazer and plug it in to a pre-TBI dash in order to get the VSS signal out of it? If so, does it just wire straight from the speedo to the ECM?
CK5
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VSS for TBI swap
- Thread starter Mastiff
- Start date
drac unit does the signal to feed the speedo or cruise control.
search 4x4high he did writeup on custom dash and wire up of a drac to feed speedo with wiring diagrams.
and i have dracs with a few pig tails modifyed send pm if needed.
search 4x4high he did writeup on custom dash and wire up of a drac to feed speedo with wiring diagrams.
and i have dracs with a few pig tails modifyed send pm if needed.
So what does the whole setup look like on a TBI vehicle? Is there no cable at all? Does the DRAC feed the speedo and the ECM? I don't have the big picture yet.
Bottom line is I want VSS for my ECM as cheaply and easily as possible!
Bottom line is I want VSS for my ECM as cheaply and easily as possible!
Stomis
Professional Amateur
TBI calculations arent dependent on vehicle speed. I dont know about the later model ones when the speedo switched over to electric but as far as my knowledge of the subject goes the vss is simply for the gauge and cruise control and Id imagine the EGR later on too.
some say tbi yes for vss and some say no.
but here is a drac box that does gear ratio and tire size calc to tell the ecm the signal it needs to be correct. and this has been modifyed for custom adjustment for diffrent tire and ratio size changes.
* * * it requires a electric sensor on the tranny or tcase output to make it work. * * *
also you can burn a chip for injection with no vss input needed.
but here is a drac box that does gear ratio and tire size calc to tell the ecm the signal it needs to be correct. and this has been modifyed for custom adjustment for diffrent tire and ratio size changes.
* * * it requires a electric sensor on the tranny or tcase output to make it work. * * *
also you can burn a chip for injection with no vss input needed.
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I've been running my TBI without VSS for years, I just want to have speed in my logs and to compute MPG. Speed is also used to get into highway mode for fuel efficiency. I'm running EBL which has adjustable pulses per mile in the program, so I just need to get the signal in. I don't know how to make that happen. How did the factory do it? Cable at T-case, or pure electric? If cable, where does the cable go? Is it cable to speedo, then wires from speedo to DRAC?
reread my post above what you just posted for answer 
Wait a second. Since my 83 had cruise control, does it already have what I need tucked away someplace? 
What kind of signal does the ECM want, does it pulse voltage or just go between ground and open?
What kind of signal does the ECM want, does it pulse voltage or just go between ground and open?
If you're going to stay with a speedo cable then you need a 1 year only speedo that uses the optic eye otherwise you change to an electric speedo and use a DRAC module. Since your current cruise control is not dependant of any kind of reference signal for speed you just won't be wiring into the cruise control.
Confusing. How does cruise control work with no measurement of speed?
Is the DRAC used to drive the speedometer or also the ECM?
I'd be okay spending $75 on one of the VSS things that goes in-line with the cable, but I need to understand how it's wired. #1 on this page:
http://www.jagsthatrun.com/Pages/SpeedSensors_Speedometer.html
Would I just ground one wire and send the other to the ECM?
Is the DRAC used to drive the speedometer or also the ECM?
I'd be okay spending $75 on one of the VSS things that goes in-line with the cable, but I need to understand how it's wired. #1 on this page:
http://www.jagsthatrun.com/Pages/SpeedSensors_Speedometer.html
Would I just ground one wire and send the other to the ECM?
I'm assuming you have a speedo cable correct? The cheapest and easiest way for you to go would be the inline speed sensor.
How is it wired up?
IIRC on a 2 wire sensor one wire goes to a keyed 12+ volt source and the other to the ECM.
I think I have one 89 speedo and optic eye left. PM me if you're interested and we'll work out details.
