Thinkin im going to be need a VSS. Now which one do i go with?

[gregs78cam]

I've got one of those optical speedometer mount deals in the shop. They are interesting.

[Six_Shooter]

Yeah, the optical sensor mounts to the back of the speedo, is what I'm talking about.

I'm using one in my Datsun. I had to modify the speedo to do so, FWIW.

The Optical VSS, needs simply an ignition connection, a ground and the output connected to the proper input on the ECM.


The silver part that is between the aluminium back piece and the odo in the picture, spins with the speedo cable, which reflects the IR light emitted by the senor and is read back by the detector. This is a Datsun speedo, but the GM speedo works on the same principle.


Close up of the optical VSS head:


This was a test fit into my modified speedo, just to illustrate the location:

[EagleMark]

That one post is worthy of a writeup!

[rokcrawlin85]

Thanks guys for all your help!!! This has been great. I'll be working on my K5 this weekend and ill take a peak and see if i have the optical there and if not, i know the part number i need. Ill be picking up a speedo cable too. I guess ill have to do a little math to figure out what speedo gear i need to swap in to get my speedometer reading right so the ECM is seeing the right numbers. If i remember right i think it was reading 7 MPH slow when i was running 35" tires, now 37"ers... So for correct readings it wants to see 1000 revolutions per mile as the driveline spins around correct?

[kunsan1987]

I have 2 versions of this buffer.the 3 wire version was for cruise control and is 2k pulses.the 4 wire one has 2 outputs .both are 2k pulse.this pic is the 4 wire the yellow wire is for ecm,the brown is for cruise control.pink/blk 12 power,blk/wht is ground.

tbi speedo vss.jpg

[rokcrawlin85]

These posts with pics really clarify what i'm looking for and how to get it wired right!!! Thanks

[EagleMark]

Yeah thanks Six and kunsan1987 for the pictures!