Speedometer question?

[Vitesse_6]

Hi all.
I am in the process of building amaurer's gauge cluster and found an oddity that hasnt been discussed.
There are a couple of wire connections on the back of the speedo that I have removed, I have no idea what they are for.

It appears to be a diode of some sort, It has a spade connector on one end of the wire and the other has a loop, Both connect into the circuit board, But I am unsure at the moment if they connect to + or - ?!?
Now, It going in a '71 FJ40, But its obviously an newer speedo setup, I dont know how to tell what year.
Thoughts?

 

[lone gunman]

yep. i have the same problem. not really sure what they are for and there is no mention in his instruction about them. for now i am just removing them.

 

[angurus]

I could be mistaken but I believe those wires are for a speed sensor connected to the
emission control computer. I'm in the process of repairing some wiring on my rig and
found that is what the blue/white wire connects to on the back of the cluster.

 

[Tobugrynbak]

That appears to be a reed switch like you find in alarm systems, which is reacting to the magnetic pulses from the speedometers flywheel "bell". It could be used to drive a cruise control, but would certainly be used in determining that the vehicle is mobile and how fast it was going.

It won't hurt to leave it in place, or take it out.

 

[FJ40Jim]

That is the VSS. Leave it there, it comes in handy for installing EFI or cruise control.

 

[lone gunman]

to leave it you would have to cut a hole or notch in Drew's bracket and i already have a VSS on my speedometer cable at the transfer case for my tuned port setup so i am pulling it then.

any idea how many pulses per mile it is ? i needed 2000 pulses per mile for my TPI

 

[Volcano cruiser]

That is the VSS. Leave it there, it comes in handy for installing EFI or cruise control.

Ok,
I give, what is VSS? I don"t have that connector on the cluster that came with the rig originally, I may have it on the nicer cluster that I swapped in a few months ago. This is relevant as I am days away from an engine/tranny/tcase swap and rewire. We are hoping that the speedo cable will screw right on and roll from there. If VSS is something interesting I might want to throw it in while I have all of this apart.

 

[Vitesse_6]

Ok,
I give, what is VSS? I don"t have that connector on the cluster that came with the rig originally, I may have it on the nicer cluster that I swapped in a few months ago. This is relevant as I am days away from an engine/tranny/tcase swap and rewire. We are hoping that the speedo cable will screw right on and roll from there. If VSS is something interesting I might want to throw it in while I have all of this apart.

Maybe the Vehicle Speed Sensor, Im not sure, Im not going to use it.
But thanks for the info all

 

[lone gunman]

yep you got it right, its a Vehicle Speed Sensor. it basically tells the computer how fast you are going or if you are moving at all so the computer knows what emission systems should be running like the EGR valve or purging the charcoal canister, running the air pump for catalytic converter emissions etc. some used 2000 pulses per mile at 60 mph and the newer stuff is 4000 pulses per mile, i have no idea what the old cruiser stuff used.

Volcano cruiser what are you swapping in ? you may need one.