THE SPEEDOMETER QUIT WORKING AND IT'S MESSING WITH THE TRANSMISSION.

  • Tiny
  • alexleahdullernorris
  • 1991 Toyota Previa
  • 500,000 miles

After a long haul pulling a car and trailer my speedometer quit working. It seems to be messing up the transmission on highway speeds telling it to shift gears when it shouldn't be. My job relies on this vehicle and would like to attempt to fix it myself if you have any advice. I can't get in to see a mechanic right away and I'm scared I'm going to either break down or get pulled over because I don't know how how fast I'm going!

Thursday, September 6th, 2012 AT 12:20 AM

6 Answers

  • Tiny
  • saturntech9
  • Expert
  • 28,821 posts

Do you have a multimeter to do some testing?

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Thursday, September 6th, 2012 AT 12:28 AM
  • Tiny
  • alexleahdullernorris
  • Member

No I don't

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Thursday, September 6th, 2012 AT 12:30 AM
  • Tiny
  • alexleahdullernorris
  • Member

Do I need one to find out what the problem is? Or is there another way?

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Thursday, September 6th, 2012 AT 12:34 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,976 posts

Get a scan done to check for trouble codes. Most parts stores provides free scanning services.

Most likely the Vehicle Speed Sensor or its circuitry is faulty. Do not jump to conclusion that the sensor is bad. It could be a loose wire or a bad circuit.

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Thursday, September 6th, 2012 AT 11:41 AM
  • Tiny
  • saturntech9
  • Expert
  • 28,821 posts

Not too sure about obd1 code scanning I know they do obd2 but obd would be a lo harder for them with all the connectors scan tool etc.

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Thursday, September 6th, 2012 AT 4:05 PM
  • Tiny
  • KHLow2008
  • Expert
  • 41,976 posts

http://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995

Japanese makes comes with a flash code retrieval for pre-OBD-II models.

Most modern scan tools comes with adapters for code retrieval for these but some are not compatabile as the ECM/PCM are not designed for scan tools as they are like those with sight windows which don't have any scan tool plugs.

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Friday, September 7th, 2012 AT 4:32 AM

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