Speedometer Gremlin

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Aug 17, 2015
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Hi all
Recently I noticed that from time to time the needle of the speedometer drops about 20 to 30 mph for about a second or even less and goes up back to actual speed again. Then some seconds repeating this behaviour while the Tachometer does not show this...
Anybody else noticed this and maybe even knows how to fix it?
Thanks
Raphi
 
Try the speed sensor first , it is cheaper. The same unit as the cam sensor. You can also reseat all connections involved. You have probably done this already. The next and most probable cause is the speedo itself.
 
Thank you Tony,
I recently changed almost all sensors. I can't remember if there are two different sensors for speed and rpm. Isn't it the same?
I thought it could also be related to the neutral light flickering gremlin, which I don't observe anymore (patch cable installed). May be there is an interference with the speed indication instead???
 
I had an intermittent problem with a wandering tachometer. The needle would slowly rise up and down or freeze at a particular RPM. Turned out to be a hairline fracture in a fuse. If you run out of ideas it may be worth checking if the speedo is connected electrically to the fuse box.
 
Hello Raphi , The Tacho connects to the ECU , and the Speedo connects to the sensor in the transmission. It may be the cam sensor ultimately that give the ECU impulses to run the tacho. I am reading the wiring diagram and this is what I see.
 
Yes , there appears to be a connection to a fuse. There are other devices also on that line. Easy enough to check the fuses for sure and just replace if in doubt .
 
Thanks Tony and Ian
I will check the fuses and report back...
 
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