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Vss ?

BoondocK5

BoondocK5

Chevrolet Bone Collector
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I've made the swap to a 1989 TBI 350 set up. do I need that little optical sensor on the back of the Speedometer to make the TBI work correctly?

If so I guess I have to swap it back out to the speedo it came with.
 
What exactly does that VSS do?
Is that what that optical sensor is on the back of the speedo?
 
it is the speedometer for the computer, im not completely sure if it is what your talking about, but it sounds like it, i know it was on the back of my speedo in my 87.
 
u can have minor issues if u dont have it, but overall u will be fine. there are plenty of ppl out there running with out one.
 
Thing is everything I'm doing to this truck is old school except that it has the TBI engine, from the 89 Suburban, I'm using the SM465 manual trans, No cruise, no antilock, No anything except the TBI I fail to see why I would need it. I've been out of the auto repair business for almost 10 years now, I forget stuff.
 
u dont need it, its more for the computer than anything else, the cruise uses it as well but abs has no part of it. computer uses that to figure in with like the egr control, iac control, it helps adjust fuel and spark curves. but like i said before its not necessary there are plenty of ppl not running one, its just a good thing to have if u can use it.
 
The ECM uses the VSS for various things such as cruise control, adjusting IAC when no load is detected (in your case between shifts and when popping into neutral) also uses it and the P/N switch to detect in gear and movement. I would not delete it. Engine can stall when depressing the clutch since the ECM has no idea that the vehicle is still moving without the VSS working.
 
Shouldn't be a big deal to swap it back in I still have the sensor and the speedo it came from. I know the plug for it is down there somewhere.
 
One other thing it does is to stop the engine from sputtering when you downshift while going downhill a bit with your foot off the gas. It's kinda nice to have.
 
I saw you swapped for the 4 speed manual, what transfer case are you running? 89 still had the mechanical speedometer 241 if i remember right.

I was wanting to swap a 6.0/4l60e into my k5, thinking it would bolt into the same place, and where i got caught was the pulse per minutes thing, so it kinda killed my ideas for that swap (pre planning had not bought anything yet) so make sure thats what your computer needs. (i think the 4l60e and 4l80e uses a 40 pulse or something around there).

Reason im asking is trying to see about using the older tcase, such as a 205 (or a 203/205 doubler) with the newer automatic transmissions, i know your running a manual. Basically, getting the older xfer case and mechanical speedometer outputs to work with the modern computers.

Hopefully your current xfer case is adaptable to the vss.
 
Nope, I going with the Dana 24, divorced, gear driven, cast iron monster out of an old ford hi-boy.
 
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