2000 VSS Pulses/Mile: Square or Sine & 12V or 5V?

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xcookpac

Apprentice
Mar 15, 2012
77
8
I understand that the stock VSS generated 2K pulses per mile. However, my questions are as follows:

i.) are the pulses analog or digital (sine wave versus square wave)? and

ii.) are the pulses 5V or 12V (or something else)?

Background: I am looking at making a 3d printed piece (I will likely be using Taulmann 910 for the 3D material) that uses plastic bolts to bolt it around the outside of the drive shaft (near the transmission tailstock). I have removed the ECM for controlling the original EM4E carb and distributor. Carb was replaced with mountain man qjet and HEI with vac and mechanical advance.

I would like to get my cruise control working again using the signal from the 3d printed piece with steel (or perhaps neo magnets) imbedded in it. My understanding is if I use a hall effect switch (generally three wires) then I will get a square wave. Alternatively, if I use a variable reluctance sensor (two wires) then I will get a sine wave.

PS I am aware that I can use the existing speedo cable, speedo, optical sensor and buffer to fix this problem also.
 
xxBLOOD88SHOTxx

xxBLOOD88SHOTxx

Greasemonkey
Jul 17, 2018
115
43
Good info on the VSS.

Correct me if I'm wrong but isn't the cruise on these controlled separately and simply hooked to the throttle arm? I'm not seeing why you have to make a new VSS and invent a new source for a pulse when you shouldn't of had to change it in the first place.

Maybe I'm just not seeing the entire scope of your project.
 
X

xcookpac

Apprentice
Mar 15, 2012
77
8
Good info on the VSS.

Correct me if I'm wrong but isn't the cruise on these controlled separately and simply hooked to the throttle arm? I'm not seeing why you have to make a new VSS and invent a new source for a pulse when you shouldn't of had to change it in the first place.

Maybe I'm just not seeing the entire scope of your project.
I don't like the original VSS system with optical sensor bolted to the back of the speedo (picking up when the light beam is interrupted by the speedo blades - found in the back of the speedo). Further, I may change out the gauges in the future and thus the optical sensor option would no longer be available..

As a result, I would like to create a relatively simple pickup off the driveshaft to act as the VSS. Additionally, when I change to LS power and 4L80E trans I can continue to use the drive shaft VSS for cruise control (while using VSS from trans to supply signal to PCM/ECM).

PS As far as the cruise being "simply hooked to the throttle arm", the servo location is compared to the VSS signal by the control module in order to keep relatively constant speed. Lot more to it than being hooked to the throttle arm.

Tags: cruise, cruise control, Cruise III, AC Cruise III, VSS, vehicle speed sensor, servo
 
Last edited:
xxBLOOD88SHOTxx

xxBLOOD88SHOTxx

Greasemonkey
Jul 17, 2018
115
43
I get how the cruise control system works, I wasn’t trying to oversimplify it. I was simply saying that at this point in time I do not see why the current system wasn’t working for you unless there was no way to connect it to your new carburetor.

There are a lot of conversions and things to make whatever you want to work. If you’re just wanting to make something for the hell of it then that’s cool.
 
84 W40

84 W40

Master Mechanic
Dec 9, 2009
317
63
I know you removed your ecm but I found this small info on the vss voltage not sure if this is what your looking for.
20190517_195617.jpg
 
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64nailhead

64nailhead

G-Body Guru
Dec 1, 2014
932
93
Upstate NY
hen yo put in the LS and 4L80, then you will have access to the VSS from the 4L80. I'm not familiar with any operating system, Megasquirt, GM stock, Holley, Fast, etc that can't handle the stock VSS signal from the 4L80. But.......if you want to have some fun and are going t put some 'go' through the 4L80, then use your hall sensor for the current VSS for a front wheel and activate traction control. Trust me, it's invigorating with big power.
 
X

xcookpac

Apprentice
Mar 15, 2012
77
8
I know you removed your ecm but I found this small info on the vss voltage not sure if this is what your looking for.
View attachment 113817

Thanks for the input. Both of my Chevy EC schematics for 1981 and 1985 do NOT show a pin 16 (referenced in the the snip that you posted).
 

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