'75 tach problem
Thread Starter
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Joined: Apr 2006
Posts: 79
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From: Madison IN
'75 tach problem
The tach seems to work fine with the engine running. However, when I go and shut the engine off the tach does not simply drop to "0" it floats up to about the 11k or 12k mark and stays there. Start the car up and she works fine..... so whats up with that?
Thanks
Tom
Thanks
Tom
Pro
Joined: May 2007
Posts: 593
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From: Warrenville IL
I want to say I read that kind of behavior is normal. Something to do with electrical charge on the line from the battery while the engine isn't running. Mine doesn't work but when I turn the keys from the off position it starts to rise until I start the car and then it just spins all the way around and stops at 0.
Drifting
Joined: Jan 2006
Posts: 1,944
Likes: 22
From: Yooperville MI
It's normal. These electronic tachs do not have a spring loaded mechanism, so the needle does not drop to zero. This design eliminates the zero adjust that some older electronic tachs had. The tach only works when power is applied to it, so the needle stays close to the last known rpm. When you turn on the ignition as when starting the car, the needle should drop to zero until the engine is running.
