Speedometer not working all the time

You could have a faulty speedometer/odometer combination meter causing a false Vehicle Speed Sensor error.
My 1998 Sienna had the following symptoms:
- Speedometer and odometer failed intermittently
- The check engine light would come on and I would get a p0500 code in the OBDII.
- The cruise control would stop working at the same time the speedometer failed.
There is a speed sensor in each one of the tires and they feed the speed information to the ABS ECU. From the ABS ECU the speed signal goes to the speedometer/odometer combination meter, and from there it goes to the Engine Control Module and to the Cruise Control ECU. I could see a signal coming into the speedometer/odometer, but no signal going out. Replacing the speedometer/odometer combination meter fixed the problem.

Usually if both the odometer and speedometer stop working, the problem is the speed sensor on the transmission. You should also have a trouble code in the engine computer.
If one component works but the other does not, the problem is usually the speedometer head in the dash.

SPEEDOMETER TROUBLESHOOTING

Can be loose speedo wiring connectors under instrument panel or its issue with speed sensor on transmission.

I suggest you to go through help links mentioned below with appropriate solutions to confirm the problem :------

How to trouble shoot speedometer?

http://schematicsdiagram.blogspot.com/2011/06/speedometer-not-working.html

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1996 fiat bravo speedometer not working?

http://technoanswers.blogspot.com/2012/01/1996-fiat-bravo-speedometer-not-working.html
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Speedometer works but odometer not working?

http://technoanswers.blogspot.in/2012/01/speedometer-works-but-odometer-not.html

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Speedometer runs backward?

http://technoanswers.blogspot.com/2012/01/speedometer-runs-backward.html

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Warning lights on and speedometer died?

http://howtobyme.blogspot.com/2011/08/warning-lights-on-and-speedometer-died.ht

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Speedometer not working on 1993 Ford F350?

http://repairhelpcenter.blogspot.in/2012/02/speedometer-not-working-on-1993-ford.html

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ABS & Brake lights warning indicator steady on dash and speedometer not working for Dodge Ram?

http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

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Vehicles Cluster panel Not reading Miles?

http://schematicsdiagram.blogspot.com/2011/12/vehicles-cluster-panel-not-reading.html

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Odometer works properly but speedometer works intermittently?

http://technoanswers.blogspot.com/2012/01/odometer-works-properly-but-speedometer.html

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These will help.

Thanks.

if the speedo is not sending a speed the trans will go into back up mode and the trans will not shift normally check the speed sensor

For speedometer related issues,the help links are provided below.Click the link below to go through its details :----

How to trouble shoot speedometer?

http://schematicsdiagram.blogspot.com/2011/06/speedometer-not-working.html

-----------
why speedometer not working? http://technoanswers.blogspot.com/2012/01/1996-fiat-bravo-speedometer-not-working.html

------------ Speedometer works but odometer not working? http://technoanswers.blogspot.in/2012/01/speedometer-works-but-odometer-not.html----------- Speedometer runs backward?

http://technoanswers.blogspot.com/2012/01/speedometer-runs-backward.html

---------
Warning lights on and speedometer died?

http://howtobyme.blogspot.com/2011/08/warning-lights-on-and-speedometer-died.html

--------------

ABS & Brake lights warning indicator steady on dash and speedometer not working?

http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

-----------
Vehicles Cluster panel Not reading Miles?

http://schematicsdiagram.blogspot.com/2011/12/vehicles-cluster-panel-not-reading.html

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Odometer works properly but speedometer works intermittently? http://technoanswers.blogspot.com/2012/01/odometer-works-properly-but-speedometer.html

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How odometer works in cars?

http://technoanswers.blogspot.com/2011/11/how-odometer-works-in-cars.html

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Speedometer not working on Ford?

http://repairhelpcenter.blogspot.in/2012/02/speedometer-not-working-on-1993-ford.html

--------

This will help.

Thanks

For speedometer related issues, the help links are provided below. Click the link below to go through its details: ----

How to trouble shoot speedometer?

http://schematicsdiagram.blogspot.com/2011/06/speedometer-not-working.html

-----------
why speedometer not working? http://technoanswers.blogspot.com/2012/01/1996-fiat-bravo-speedometer-not-working.html

------------ Speedometer works but odometer not working? http://technoanswers.blogspot.in/2012/01/speedometer-works-but-odometer-not.html ----------- Speedometer runs backward?

http://technoanswers.blogspot.com/2012/01/speedometer-runs-backward.html

---------
Warning lights on and speedometer died?

http://howtobyme.blogspot.com/2011/08/warning-lights-on-and-speedometer-died.html

--------------

ABS & Brake lights warning indicator steady on dash and speedometer not working?

http://howtobyme.blogspot.com/2011/11/abs-brake-lights-warning-indicator.html

-----------
Vehicles Cluster panel Not reading Miles?

http://schematicsdiagram.blogspot.com/2011/12/vehicles-cluster-panel-not-reading.html

---------
Odometer works properly but speedometer works intermittently? http://technoanswers.blogspot.com/2012/01/odometer-works-properly-but-speedometer.html

---------------
How odometer works in cars?

http://technoanswers.blogspot.com/2011/11/how-odometer-works-in-cars.html

--------------
Speedometer not working on Ford?

http://repairhelpcenter.blogspot.in/2012/02/speedometer-not-working-on-1993-ford.html

--------

This will help.

Thanks

neoprene gear in transmission were the speedometer cable goes into transmission should not have a dished appearance if you pulll it out of transmission look at it from the side it should appear flat from the start of the gear to end of gear no dish down in center

Could be a ciggerette lighter fuse, usually cause this when it blows.

Most likely a speed sensor is going bad (most cars and truck do not use mechanical speedometer cables anymore) most sensors are located near the differential in rwd cars or near the drive shaft on the transmission. Best bet is to get a Haynes manual for your car to help locate the speed sensor. Remove it and take it to the auto parts store so you can visually compare it to the replacement. Install the new speed sensor and it should restore your speedometer and odometer.

Sounds like either your speedometer cable, your nylon gear on the side of the tranny where the cable ties in, or the odometer itself is shot. One of those three will set you straight. If you are able, remove the cluster, take the cable off the back, and pull it out of the sheath. You will see if its broken or not from there. If not, slide it back into the sheath, then you have to find out where the sheath meets the tranny, and pull it off of there. Then, you can get someone else to watch the speedo as you turn the cable from the bottom. If it works, great, if not, then its your cluster/odometer/speedo. If it does work, the small gear in the transmission is shot.