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Old 01-30-2013, 08:21 AM   #1
petefozzy
 
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Speedo keeps going on and off

Hi hope some one can help I have a 1999 yaris and the speedometer keeps disapearing then some times it will re appear straight away then other times takes ages just wondered if some one else has had this problem and can help thanks.
Pete
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Old 01-30-2013, 08:52 AM   #2
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That could be a couple of things. The speedo is fed by the speed sensor on the transmission, so it could be the sensor itself, or the wiring between it and the speedo.

Also, the speedo gets a pulsed signal from the speed sensor and then drives a tiny servo motor to move the needle. Those little servo motors can fail as well.

Since the speedo can only be diagnosed in motion, your best bet may be to swap speedos with someone else temporarily to see if the issue follows the speedo or the car.
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Old 01-30-2013, 09:13 AM   #3
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Thanks for the reply I will have a look at the speedo sensor and wiring when the weather gets a bit better.
Thanks Pete
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Old 02-08-2013, 10:55 AM   #4
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Hi still having trouble there seems to be nothing wrong with the actual speedo its the display that keeps going on and off but when it comes back on it has recorded the milage I have done and also the tripometer so its just the display just wondered if it could be a loose bulb on back of speedo or dirty connection on connectors but dont know what feeds speedo any help welcome.Or how to get to back of speedo to check.
Thanks Pete
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Old 02-08-2013, 11:22 AM   #5
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Do you have the digital or analog speedometer?

With the odometer working, it is definitely the speedometer itself that is the issue and since the odo works, it is likely not a connection issue to the back of the speedometer assembly. If it is the analog version, then the little servo motor that moves the needle can wear out.
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Old 02-08-2013, 11:29 AM   #6
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Thanks for the reply it is a digital diplay on a 1999 yaris.
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Old 02-08-2013, 11:37 AM   #7
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Originally Posted by petefozzy View Post
Thanks for the reply it is a digital diplay on a 1999 yaris.
OK. With the digital one, it could be a problem with the VFD (Vacuum Fluorescent Display) or its driving circuitry.

The pictures below show the inside of a 2006-2011 one, but I suspect that the first gen one is similar. The speedometer portion of the display is connected to the main circuit board via a ribbon cable. The cable connection may be loose causing the intermittent behavior.

You can pull the trim off around the instrument cluster to then remove the assembly.

Digital Cluster - Open.jpg

Digital Cluster - Connector.jpg
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Old 02-08-2013, 11:44 AM   #8
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Once again thanks for you input I will take out the speedo and see what I can find.
Thanks peter
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Old 02-08-2013, 12:30 PM   #9
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Hi took out speedometer cleaned everything still the same just wondered if the speedo sensor could cause this and were is it located and any way of checking it or taking it out and cleaning it just to see if it made any difference if so would this be hard to do .
Thanks Pete
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Old 02-08-2013, 12:34 PM   #10
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Originally Posted by petefozzy View Post
Hi took out speedometer cleaned everything still the same just wondered if the speedo sensor could cause this and were is it located and any way of checking it or taking it out and cleaning it just to see if it made any difference if so would this be hard to do .
Thanks Pete

When the speedometer stops working, does the speedometer display go completely blank (and does the separate odometer display also go blank)?
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Old 02-08-2013, 12:48 PM   #11
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Yes it does and so does the fuel Gauge but other things like left and right turn work and temperature airbag light all work.
thanks
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Old 02-08-2013, 01:52 PM   #12
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Originally Posted by petefozzy View Post
Yes it does and so does the fuel Gauge but other things like left and right turn work and temperature airbag light all work.
thanks
The indicator lights are driven by separate circuits. There are three circuits that feed the electronics for the speedometer, odometer, fuel gauge. The Ignition switch, the 15A ACC fuse and the 10A Gauge fuse supply the power to those functions, so I would check the brown wire in pin 1 of connector C13, the grey wire in pin 19 of Connector C15 and the red wire with the blue stripe in pin 8 of connector C13.

All three of those should have 12 Volts on them. if one does not, when the speedometer is not working, then that particular feed is the issue (for example it could be that the ACC relay contacts are not closing properly if the grey wire does not have 12 Volts on it).

1999 - cluster C13.jpg

1999 - cluster C15.jpg
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Old 02-08-2013, 02:21 PM   #13
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Hi thanks again for your help I am most grateful could you please tell me were connector c13 and c15 are located and once again I am so grateful for your help in this matter.
regards pete
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Old 02-08-2013, 02:28 PM   #14
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Originally Posted by petefozzy View Post
Hi thanks again for your help I am most grateful could you please tell me were connector c13 and c15 are located and once again I am so grateful for your help in this matter.
regards pete
On the speedometer assembly. C15 is on the front and C13 is on the rear.
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Old 02-09-2013, 05:53 AM   #15
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Hi again checked all the connections all seem ok so now at a loss as what to do next does this point to a faulty speedometer or to the speedo sensor because all of a sudden the display will come back on and all seems well for awhile before it goes off again.
Thanks Pete
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Old 02-09-2013, 08:15 AM   #16
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Originally Posted by petefozzy View Post
Hi again checked all the connections all seem ok so now at a loss as what to do next does this point to a faulty speedometer or to the speedo sensor because all of a sudden the display will come back on and all seems well for awhile before it goes off again.
Thanks Pete
If the speedo sensor was bad you would just see 0 MPH, as opposed to a blank display, so it really points to an intermittent power feed to the speedo or an intermittent fault on the circuit board. Do you have anyone that you can temporarily swap speedometers with to see if it follows the car or the speedo?
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Old 02-09-2013, 08:24 AM   #17
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Thanks I will see if I can get hold of one to try are they all the same even diffrent years my local breakers yard has one and he assures me that it works so may have to purchase that as dont think it is speedo sensor and all power to speedometer seems to be ok.
once again thanks for your help.
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Old 02-10-2013, 05:26 AM   #18
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Hi could you please confirm wether this connection is C15 please before I go buy a diffrent speedometer thanks. The other one on top is for thr tripometer.

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