Questions about VSS

Michael Yount

Mustang Master
Apr 10, 2002
9,039
6
79
Charlotte, NC
I've asked before, but remain confused. Trying to learn about the Vehicle speed sensor in the fox body stangs. Does anyone know exactly where the sensor is located and how it works? I've got information that seems to indicate it's internal to the T-5 - there's an electrical connection near the front of the tranny that has wires which run inside the top of the tranny near the front. I've got other info that indicates the VSS is a sensor which goes in between the speedo cable and the tranny - with a wiring connection that comes off of it.

I want to try hooking up a VSS to the rest of my ecu circuit (I know it connects at pins 3 and 6), and would also like to use it to drive my cruise control allowing me to remove the magnets/pickup on the driveshaft.
 
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My '88 does not have factory Cruise control. But the dealer installed CC before selling it to the previous owner. I noticed when i bought the car that the speedo cable was messed with. There was now a 2-peice cable with a ring with some wires attached to it. A red and black wire specifically. I have always wondered what these were for. I want to convert to MASS AIR soon and the instructions say i need to tap into the VSS wire.

WHen i did a conversion on a freiend's '88, we tapped into the VSS on the tranny.

So what is on my cable?
 
Ok I can tell you were it is. Follow the speedocable back to the trans, it is on the end of it. this is what it looks like
VSS%20sensor.jpg


Here is the info your looking for to

VEHICLE SPEED SENSOR SIGNALS
These signals are required for cruise control and as stated earlier, some have reported stalling problems on cars not equipped with cruise so avoid the head-ache and just do it. These will also generate an error code in the EEC if not installed. These signals come from a sensor that plugs into the transmission. The easiest place to tap into them is behind the driver's side kick panel. There is an 8 pin connector cable which runs back to the driver's seat, across the floor under the seat then back towards the front of the car and then goes through the transmission hump to the sensor. You will need to splice into the orange/yellow wire. The other end of this signal needs an EEC pin attached and this gets inserted into the EEC connector into position 6. You need to splice into the dark green/white wire for the other connection. The other end of this signal needs an EEC pin attached and this gets inserted into the EEC connector into position 3. Refer to figure 2.

fuelharness2.jpg
 
Mustang5L5 said:
My '88 does not have factory Cruise control. But the dealer installed CC before selling it to the previous owner. I noticed when i bought the car that the speedo cable was messed with. There was now a 2-peice cable with a ring with some wires attached to it. A red and black wire specifically. I have always wondered what these were for. I want to convert to MASS AIR soon and the instructions say i need to tap into the VSS wire.

WHen i did a conversion on a freiend's '88, we tapped into the VSS on the tranny.

So what is on my cable?


I converted to mass air and didnt use a VSS several people have done this with no problems. They claim it can cause stalling But I havent experienced this problem.
 
JKstang - GREAT detail - thanks for the reply. If I go to Autozone and ask for the VSS for a 92, I presume I'll get the whole piece shown in your pic? Does the speedo cable plug into the VSS? What holds it in? My speedo cable has the clamp with the single bolt to hold it into the tranny as shown on the VSS. I'm curious how the speedo cable is fastened to the VSS. Also curious about wiring - since I don't have the wiring harness inside the car that you've described, I've got to figure out which connection on the VSS goes to #3 ecu pin, and which one goes to #6. Any thoughts on how to do that? Perhaps the easiest way is to buy a used (junkyard) pig tail that plugs into the VSS. Then I can use the color-code you've provided above.
 
ok from this pic it looks like that the positive of the vss goes to 3 and the negative side to 6. I save the pic and then blow it up. It is so unclear that I am having trouble figure out which is which but I do think I see a + over the number 3 link to the pic
http://www.geocities.com/smithmonte/Auto/88_91_50L_MAF_SFI.htm

Ok the speedo cable does go into the vss sensor. It is held in buy a small metal clip I want to say it look like a hood pin. Not sure how to describe it.
 
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An ABS system simply uses the VSS signal to determine road speed. It also uses sensors at each wheel to determine the wheels' speed. The ABS computer compares those two signals - and when wheel speed is less than road speed under braking, it interprets that condition as 'lock up' and releases pressure on the brake until the road speed and wheel speed are close to matching again. A traction control system compares the same signals, but controls in the other direction. When wheel speed exceeds road speed, a traction control system interprets that as tire spin, and it then takes steps to either reduce power, or apply the brakes until the speeds are close to matching again.

JKStang - thanks for the additional info - I'll head to the junkyard and parts stores and see what I can find out.