1997 Ford Taurus Speedodometer and Transmission

Tiny
BONSAIEE
  • MEMBER
  • 1997 FORD TAURUS
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 56,000 MILES
Dear sir:

While I was driving on freeway about 120 miles away from home, I suddently noticed the speedodometer stopped working, the needle indicated at zero speed (the actual speed was about 60mph). I also noticed the Engine Service light came on. I pulled over, turned off engine and restarted then started driving. The speedodometer started working fine but the Engine Service light remained on.

After driving for couple miles, the speedodometer stopped working again. When I pulled over and turnned off the engine, then restarted the engine. When I shifted my transmission to "D" anb stepped on the gas pedal, I noticed the RPM meter went up to 3000rpm and the engine sound very loud but the actual car speed is about 10mph. It seem like the transmission still at first gear and couldn't shift to second gear. I turned off the engine and checked the transmission fluid and engine oil; I noticed both are sufficient. I didn't know what to do next and extremly worry, I restarted the engine and shifted the transmission lever to "D" and slowly stepped on the gas pedal. The car started driving and the transmisson shifted to second gear and worked normally as if nothing went wrong. I continued monitored the Engine Sevice light and speedodometer until I got home. During this time, the Engine Sevice light always remained on; however, the speedodometer was working intermittently.

I've driven this same car to work for three days (my work place is seven miles from home). The Engine Service light stil remained on; however, the speedodometer and the transmission stop showing problem.

I have two questions:
1) What made my speedodometer working intermittently?
2) Why my tranmission failed to shift then just work fine now?
3) Are these two problems related?

Your answers in great detail are greatly appreciated.

Regards,
Bonsaiee
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Thursday, June 3rd, 2010 AT 7:00 PM

9 Replies

Tiny
SATURNTECH9
  • EXPERT
I would say the two are related and you probably have a sensor or wire issue. Go to a auto parts store like autozone and have them read your codes bring me back the numbers and we will go from there.
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Thursday, June 3rd, 2010 AT 7:10 PM
Tiny
RETIREDMECHANIC
  • MEMBER
More than likely a VSS went bad. A VSS not only controls the spedo but also tells the computer how fast your car is going, thus creating the correct shift points for your transmission. VSS (vehicle speed sensor)
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Saturday, June 5th, 2010 AT 7:48 PM
Tiny
BONSAIEE
  • MEMBER
Dear RetiredMechanic:

I appreciated for your response. I noticed that the warnning light has been off for the last couple days and the symptoms that I described to your team haven't occurred again.

Would you explain why everything has been working fine since last Wednesday?

Why the symptom failed intermittently? Where is the VSS located in the car?

Is it the same sensor that your fellow (Saturntech9) mentioned in his assesments posted on last Thursday?

Best regards,
Bonsaiee
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Monday, June 7th, 2010 AT 7:19 PM
Tiny
RETIREDMECHANIC
  • MEMBER
When I sold my shop, all books and information went with the shop. However I believe the VSS on your Taurus is located on top of the output shaft housing on the passenger's side of the vehicle. Just under the VSS and spedo cable there is a shaft with a gear on it, pull the shaft and gear out and make sure the nylon gear is not worn out. It is hard to believe it went out at 56,000 miles but again it could have. There should be a protective shield over the VSS and cable, this is to shield it from the heat of the exhaust. The VSS picks up small electrical pulses, sends the signal to the computer and the gear drives the cable to the Spedo. A Vss is usually easy to replace. I would suggest finding a good Transmission shop and having them double check the VSS, wiring connector and the drive gear on the shaft if you have problems figuring it out for yourself.
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Monday, June 7th, 2010 AT 8:29 PM
Tiny
BONSAIEE
  • MEMBER
Dear RetiredMechanic,

I appreciated for your prompt reply to my questions.

I have a mechanic man who lives next to my house. He offerred to look at it. If I've further questions, I'll ask you again.

Best regards,
Bonsaiee
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Tuesday, June 8th, 2010 AT 3:51 PM
Tiny
BGBEVAN
  • MEMBER
1997 Taurus, 200K mi. I had the classic problem indicating a speed sensor failure. Speedo didn't work and transmission shifted hard or stuck in low gear when heated up. There are two sensors on the transmission, the Vehicle Speed Sensor(VSS) located on the output shaft of the transaxle on the passenger side, and the Turbine Shaft Sensor(TSS) located under the exhaust manifold on the input shaft, accessible from the driver's side. I thought the VSS was bad but couldn't find it and ended up changing the TSS. This fixed my problem so my question is, which one of these sensors drives the speedometer? Both, VSS, or TSS? Most posts on this issue say to change the VSS when this problem occurs and make a vague reference to the TSS.
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Saturday, July 30th, 2011 AT 7:07 AM
Tiny
SATURNTECH9
  • EXPERT
The vechile speed sensor measures the differential speed in the transmission to calculate vechile speed. The tss measures the input shaft speed in the transmission. So the vss would drive the speedometer.
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Saturday, July 30th, 2011 AT 4:37 PM
Tiny
BGBEVAN
  • MEMBER
Thanks saturntech9 for the quick response. So, the logic says that I changed the VSS which fixed the problem. (Never did figure out where the TSS is but will leave that for another day.) I was able to get at the VSS from the drivers side of the engine with a long reach and a 10 mm socket and short extension. I read numerous blogs and forums that talked about dropping exhaust pipes, jacking up the engine, taking off the tires, etc. Also, repair estimates of $200 to $750. I didn't need to disconnect anything to complete the repair. It would take about 1/2 hour if I had to do it again and it's only the price for a new VSS. About $16 @ NAPA. Probably $75 for Ford OEM. I have the procedure and a few pics if anyone is interested. Think this works for a 1998-1998 Taurus. Bgbevan@earthlink. Net
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Saturday, July 30th, 2011 AT 5:12 PM
Tiny
SATURNTECH9
  • EXPERT
Your welcome thats what were here for.
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Saturday, July 30th, 2011 AT 5:17 PM

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