AC signal of 2 wire VSS

[itzik93]

Hi,

 

Well, after checking the VSS again im totally confused. I was almost sure that the VSS is not OK but i think i was wrong.

Checked the VSS again today, there is a pefect AC signal from the VSS, starting with 0.xxx volts from the 1st cm that the vehicle moves and a good linear signal (around 8 Volts at 60-70 Km/h).

 

From what i've searched the forum, the signal should be around 0-5 Volts but im guessing that there are few models of VSS with 2 or 3 wires and if i get a good linear signal then the sensor is OK, even if the AC signal around 60-70 Km/h is around 8 volts.

 

For those who knew vss/speedometer problems, have you checked the AC signal from the VSS and can confire this ?

 

I guess now i have to deal with the speedometer head, has anyone tried to fix it ? mine doesnt work good below 20-30 Km/h, only above everything is working good.

 

Thanks...

 

Izik

[Legacy777]

The cable might be sticking. it'd probably be worth taking the cable out, if it's caked up, take the casing out as well, spray the inside with brake cleaner, and then regrease everything.

[itzik93]

The cable might be sticking. it'd probably be worth taking the cable out, if it's caked up, take the casing out as well, spray the inside with brake cleaner, and then regrease everything.

 

10x for answering but what cable r u talking about ?

 

Its a 96 Legacy and the speedoemeter guage is getting signal (AC signal, not DC) from the VSS (2 wire). no cable.

 

I've checked the harness and its ok. I suspect that the VSS signal is too weak in the begining because the speedometer is working only from 20~km/h.

 

The VSS is none-fixable/sealed-unit ***but*** i succeeded to open it (i also have pictures that i will upload later).

I cleaned inside the VSS and closed it (with tuff hard glue). The VSS is actully a small motor that produce AC voltage when you turn it. The Speedometer guage is getting AC signals (waves) and compail them.

I suspect that the AC waves that the VSS is producing under 20 km/h are too weak.

 

Since then (then=opening the VSS) the speedometer is working only from ~20 km/h (before that the was working alternately - somtimes perfect from 0 and somtimes from 20-50 km/h.

 

Any idea's ?

 

Izik

[BigMattyD]

I have an idea. Get a new sensor. I think they cost around 60 dollars.

 

 

Matt

[Legacy777]

My bad! Spaced, and was thinking about the older VSS.

[itzik93]

I have an idea. Get a new sensor. I think they cost around 60 dollars.

 

 

Matt

 

A new VSS costs here around ~120$, not cheap... but i guess i will try to find one in the jankyard (or maybe its a bad idea ? donno...)

 

BTW: this is how the VSS looks inside:

 

 

 

 

[hklaine]

I don't think that the strength of the signal is your problem. As far as I know the speed is calculated from the frequency of the wave, not the amplitude at peak (which should be constant). Maybe the "motor" doesn't spin freely at low RPMs (flat spot or worn)? Is the gauge accurate at higher speeds?

 

Just my thoughts on the topic.

 

-Heikki

[itzik93]

I don't think that the strength of the signal is your problem. As far as I know the speed is calculated from the frequency of the wave, not the amplitude at peak (which should be constant). Maybe the "motor" doesn't spin freely at low RPMs (flat spot or worn)? Is the gauge accurate at higher speeds?

 

Just my thoughts on the topic.

 

-Heikki

 

2 things:

 

1. I think ur wrong. I've checked with the volt-meter and the "motor" spins prefectly and generates AC voltage perfectly.

 

2. An hour ago i replaced the VSS with a new one (104$ + tax at the dealr's main garage) and now the speedometer is working PERFECT !!!!

 

The meaning is that the old VSS had short waves when spining slowly...

 

 

BTW: Ordering the sensor from the internet costs 65$ + 30$ of shipping (95$ total) which are not too far away from the price here.

 

Thanks for everyone that helped !!!

 

Izik