How to test VSS Vehicle Speed Sensor

[U R A BUS]

I have a 98 Legacy GT and would like to know how to test the speed sensors.

I am told these are what control my AWD. If I need to replace them does anyone have idea of the cost and are they available aftermarket?

[1-3-2-4]

pretty sure if the speed sensor did not work the car goes into limp mode Rev is limited to no higher then 4K also the speedo would most likely act funny.

[aa8jzdial]

I recall digging into this with a Forester.

Pull out the sensor and spin the drive mechanism with a variable speed drill.

What you couple the chuck to resembles a flat blade screw driver tip.

Might take a little Mcguivering with tape or such.

Run the drill and have someone watch the speedo.

Just have the ignition switch in run.

 

I have seen 2 and 3 wire sensors. My frogging around lead me to conclude the 2 wire sensor is based on a magnetic pickup design. It generates it's own signal. Don't know how many pulses per rev.

 

The 3 wire units use

#1, ground,

#2, +12 volts, or maybe 5 volts (can't recall)

#3 pulse out. The one I checked produced 4 square wave pulse per rev.

 

Probably more then you want to know.

 

I would certainly look in the junk yards before going to Sub guys.

Good luck

rick

[nipper]

I have a 98 Legacy GT and would like to know how to test the speed sensors.

I am told these are what control my AWD. If I need to replace them does anyone have idea of the cost and are they available aftermarket?

 

Yes they control your AWD. Loose one and loose your awd, you should get a CEL. Loose two and you'll loose the spedo and AWD and have a CEL. You will also not be able to go faster then 50mph. The either work or dont so if you dont have any CEL or codes dont worry about them. they tend to be robust.

 

 

Which leads to the next question, are you having AWD issues?

 

 

nipper

[U R A BUS]

What is A CEL? yes I am having AWD issues. AWD works for about 30 seconds then quits. I can immediately turn car off and restart and AWD works for about 30 seconds then quits. I can immediately turn car off and restart and AWD works for about 30 seconds then quits. I can immediately turn car off and restart and on and on it goes.

[nipper]

Is this a repeat post, thought there was another one like this.

 

If you dont know what a CELK is then dont go diging around the tranny.

A CEL is a Check Engine Light.

 

Do you have a flashing AT Temp light on startup?

 

 

nipper

[U R A BUS]

Is this a repeat post, thought there was another one like this.

 

If you dont know what a CELK is then dont go diging around the tranny.

A CEL is a Check Engine Light.

 

Do you have a flashing AT Temp light on startup?

 

 

nipper

 

 

LOL Nipper. I am just not good at acronyms. I am quite capable of digging in the tranny but dont want to if I dont have to cause if I open it up I will probaly change clutches, seals, duty c and whatever else is recommended cause i only want to go in there once.

I know the trans temp light comes on when you start it but dont remember if it flashes. The car is not home right now but I will check when it gets back.

Yes this is a repeat post cause for some reason I couldn't get back to the original, but now i can. So what does it mean if the light is flashing? not flashing?

[nipper]

LOL Nipper. I am just not good at acronyms. I am quite capable of digging in the tranny but dont want to if I dont have to cause if I open it up I will probaly change clutches, seals, duty c and whatever else is recommended cause i only want to go in there once.

I know the trans temp light comes on when you start it but dont remember if it flashes. The car is not home right now but I will check when it gets back.

Yes this is a repeat post cause for some reason I couldn't get back to the original, but now i can. So what does it mean if the light is flashing? not flashing?

 

The light (if it) flashes 16 times means there was an electrical fault the last time the car was operated, and there will be codes. this is NOT an obd2 code, but a seperate code set and procedure.

 

how many miles on this anyway?

[U R A BUS]

184,000

[nipper]

184K is high enough for it to be a tired clutch pack.

[Gloyale]

Someone with a Scan tool that has streaming data could tell you right away.

 

Just take it for a drive and watch the values on the scan tool.

 

Also, you can just hook a multimeter onto the VSS wires set to AC volts. spin the sensor, and the voltage should rise steadily, or at least give you a pulse depending on how fast you spin it.

[U R A BUS]

184K is high enough for it to be a tired clutch pack.

 

WOW this is really gettin wierd. I didn't mention earlier that you didn't need to step on the brake to shift this car out of park. Today it wouldn't shift unless I stepped on the brake. And guess what the AWD works fine today. It work for as long as I drove the car about an hour. So logic would tell me the clutch pack is ok and it has got to be some kind of electrical problem. It does not have any CEL or flashing lights. If anyone has an idea please share it with us.