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tachometer inop


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gahumble
User

Apr 26, 2012, 1:09 PM

Post #1 of 6 (2188 views)
  post locked   tachometer inop  

1995 nissan p/u 4x4 2.4L. tach was stuck @ 3000 now it's pegged. any ideas? i have a haynes and chilton book, no info.


Discretesignals
Ultimate Carjunky / Moderator
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Apr 26, 2012, 3:24 PM

Post #2 of 6 (2158 views)
  post locked   Re: tachometer inop  

Does it come back down when you shut the engine off?





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gahumble
User

Apr 28, 2012, 10:09 AM

Post #3 of 6 (2121 views)
  post locked   Re: tachometer inop  

yes, it drops back to 0. yesterday i started it, tach went to 1200 and stuck. back to 0 when key off


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Apr 28, 2012, 10:49 AM

Post #4 of 6 (2113 views)
  post locked   Re: tachometer inop  

Probably wouldn't be a bad idea to start by checking power and grounds circuits to the tachometer.

You can do this using a volt meter and backprobing the insturment panel connectors. I can give you step by step instruction on how to do this, but you have to have a volt meter and understand how to use it.

The only problem you'll have is if the power and grounds are good and you need to verify the signal from the ECU to the tach. You'll need something fast to watch the signal such as a graphing multimeter or oscilloscope. You also may need a enhanced scan tool for Nissan to look at the ECU data stream information to be sure the ECU is reading the correct RPM signal.

One last thing is to be sure you don't have some sort of interference problem such as secondary ignition leaks causing the signal to the tach to be corrupted. I know all this sounds pretty complicated, but your working with electrical circuits and signals and they are complicated in themselves.





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gahumble
User

Feb 6, 2013, 11:33 AM

Post #5 of 6 (1915 views)
  post locked   Re: tachometer inop  

sorry. customer didn't care if it works


Discretesignals
Ultimate Carjunky / Moderator
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Feb 6, 2013, 4:50 PM

Post #6 of 6 (1893 views)
  post locked   Re: tachometer inop  

Thanks for the follow up. Since customer denied repair or diagnosis, topic is closed.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






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