new vss and still no speedo

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cooper

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Dec 9, 2005

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Sep 13, 2006

#1

• Sep 13, 2006

• #1

my speedo hasn't worked in months! under the guidence of auto zone, and ford analisis, its the vss. (vehicle speed sensor.) well i changed it and it lasted about 20 min. Then no speedo, or odo. the last upgrade was m-m f/l sub frames welded in . the shop told me the battery was disconected. could it be a short in the computer? ive also heard the alternator could cause problems like this? Or maybe i got a bad vss from the dealer? about 3 weeks ago the batery died, so i instaled an optima! I KNOW NOTHING ABOUT ELECTRONICS! oh please say its not eletric

 

C

cooper

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Dec 9, 2005

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Sep 14, 2006

#2

• Sep 14, 2006

• #2

anything?

 

Mike97gt

it doe snot

Founding Member

Jan 26, 1999

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the people's republic of massachusetts

Sep 14, 2006

#3

• Sep 14, 2006

• #3

remove the VSS sensor and check the gear on the VSS and the gear in the tranny. You might have a problem with the gear in the tranny.

BTW never trust anything the autozone guy tells you.. they have no training or background in EEC diagnostics. Sadly most mechaincs also have no training and suck at EEC diag. put it this way out of the hundreds of techs I have worked with over the years, I might trust the EEC diags from 3 of them.

So anyways back on topic. First check the gears both on the sensor and tranny then your going to want to check the wires from the VSS, those are exposed and can easily be damaged.

 

C

cooper

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Dec 9, 2005

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Sep 14, 2006

#4

• Sep 14, 2006

• #4

this vss is just a sensor, no gears on it. ill check the plug and wires this weekend.

 

Mike97gt

it doe snot

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Jan 26, 1999

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Sep 14, 2006

#5

• Sep 14, 2006

• #5

what year is the car.. 99+ cars have a output shaft speed sensor that does not have a gear on it. the 96-98 cars have a old school vss sensor that has a gear on the bottom of it.

when you said VSS I assumed you had a 96-98..

It's possible you have gotten a bad sensor another possibility is a damaged wire near the connector. or even a damaged pin in the connector itself. this could explain why it worked for a short period of time.

 

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speedytang

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Jul 28, 1999

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Marengo,Ohio,US

Sep 15, 2006

#6

• Sep 15, 2006

• #6

Remove the sensor and put a ohm meter on it and spin it with your hand and see if you get a reading. I would think it is a wiring issue from the computer to speedo. If the VSS was not working your car usually won't shift if it is a auto and if it is a stick the idle will not usually drop when you come to a stop. You don't say you have other issues so that is why I think it is from the computer to the speedo.

 

BlueStang73

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Apr 17, 2002

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San Antonio Texas

Sep 15, 2006

#7

• Sep 15, 2006

• #7

same thing happened to me but the sensor usually dosent come with a gear when u purchase it..so u gotta get the rear end gear raito so that u get the right gear

 

RandyStinchcomb

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May 25, 2005

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Randallstown, Md

Sep 15, 2006

#8

• Sep 15, 2006

• #8

check to make sure the dealer got you the right output shaft speed sensor, not only are there different ones but even the correct ones for the Mustangs was up-graded on 5/26/06 from a XR3Z-7H103-AA to a newer part # because of issues wth the old stock. newest part # for the Mustangs is XR3Z-7H103-AB these # are for a manual trans, autos have several more different #'s that are NOT the same thru the years

 

C

cooper

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Dec 9, 2005

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Sep 15, 2006

#9

• Sep 15, 2006

• #9

my car is a 2000 gt with a 5-speed. im using vss just to shorten things up. yes its just an eye, no gears. some thing else the motor rpm's drop and sometimes it will just quit , when im stoping at a light. this seems to hapen more when the a/c is on, but it hasent staled in a while because im more aware and touch the throtle. the motor will drop to idle and then drop to 400 rpm for a sec then pick it self back up to normal idle. Blue stang i live in san antonio also, med center.

 

RandyStinchcomb

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May 25, 2005

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Sep 16, 2006

#10

• Sep 16, 2006

• #10

cooper said:

my car is a 2000 gt with a 5-speed. im using vss just to shorten things up. yes its just an eye, no gears. some thing else the motor rpm's drop and sometimes it will just quit , when im stoping at a light. this seems to hapen more when the a/c is on, but it hasent staled in a while because im more aware and touch the throtle. the motor will drop to idle and then drop to 400 rpm for a sec then pick it self back up to normal idle. Blue stang i live in san antonio also, med center.

Click to expand...

that sounds like an IAC problem to me, try and re-move it and clean it wth some solvent and a old tooth brush, also you might consider changing your PCV valve

 

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speedytang

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Jul 28, 1999

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Marengo,Ohio,US

Sep 16, 2006

#11

• Sep 16, 2006

• #11

The IAC gets a signal from the VSS.

 

RandyStinchcomb

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May 25, 2005

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Randallstown, Md

Sep 16, 2006

#12

• Sep 16, 2006

• #12

speedytang said:

The IAC gets a signal from the VSS.

Click to expand...

yeah but that doesn't explane his original concern of the speedo not working?

 

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speedytang

Founding Member

Jul 28, 1999

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Marengo,Ohio,US

Sep 16, 2006

#13

• Sep 16, 2006

• #13

Yes it does because the speedometer uses the VSS for its reading.

 

C

cooper

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Dec 9, 2005

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Sep 16, 2006

#14

• Sep 16, 2006

• #14

I looked at the plug and wires today, they all looked good. no dirt or junk in the plug. no responce. as far as the iac it's about 1 year old, had that problem before, ill clean and lube it tomorow just to see. the pcv is stock and it still makes the Im still good rattle when shaken. I did notice the part number on the vss was the old -AA not the updated -AB, maybe this could be it?

 

Mike97gt

it doe snot

Founding Member

Jan 26, 1999

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the people's republic of massachusetts

Sep 16, 2006

#15

• Sep 16, 2006

• #15

OK now you got a different problem?

the VSS or OSS sensor has nothing to do with the IAC. the only thing they have in common is they are connected to the pcm.. one of them ( vss,oss) being a input and the IAC being a PCM output.

The PCM should command a higher IAC percentage as the RPM's drop regardless of what is going on with the OSS circuit.


I would clean the iac out and give it a few small taps with a hammer to clean it out and break up any carbon in there. Then I would focus on your OSS problem.

As randy said you may have been given the wrong part.. It may also be a defective part.

Another possibility is a very very rare condition where the sensor wheel in the tranny becomes magnetized. even a slight change in the magnetics can ruin the OSS signal. the fact that it worked for twenty minutes points to a possible magnetized sensor or tone wheel.

 

C

cooper

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Dec 9, 2005

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Sep 16, 2006

#16

• Sep 16, 2006

• #16

A new oss or vss sounds like the most friendley on my walet. But with my luck this magnetized event seems more likley! thanks for the posts