Tachometer Not Working!! The Agony!!
Thread Starter
6th Gear
Joined: Apr 2014
Posts: 6
Likes: 0
From: Maple Ridge BC
Tachometer Not Working!! The Agony!!
So I am new to the forums, but have been an avid watcher/viewer/listener?? since I bought my corvette 4 months ago.
The tachometer didn't work when I bought it, and the previous owner said I needed to replace the Tach filter. After doing so, still nothing. The needle sits well below 0rpm and nothing moves it. Before I go into the dash is there anything else that could be the problem? I also have a voltmeter if that can help with diagnosis.
The tachometer didn't work when I bought it, and the previous owner said I needed to replace the Tach filter. After doing so, still nothing. The needle sits well below 0rpm and nothing moves it. Before I go into the dash is there anything else that could be the problem? I also have a voltmeter if that can help with diagnosis.
Racer
Joined: Aug 2008
Posts: 413
Likes: 22
From: Justin TX
What year
So I am new to the forums, but have been an avid watcher/viewer/listener?? since I bought my corvette 4 months ago.
The tachometer didn't work when I bought it, and the previous owner said I needed to replace the Tach filter. After doing so, still nothing. The needle sits well below 0rpm and nothing moves it. Before I go into the dash is there anything else that could be the problem? I also have a voltmeter if that can help with diagnosis.
The tachometer didn't work when I bought it, and the previous owner said I needed to replace the Tach filter. After doing so, still nothing. The needle sits well below 0rpm and nothing moves it. Before I go into the dash is there anything else that could be the problem? I also have a voltmeter if that can help with diagnosis.
Year
engine and basic info
is it original or a modified setup
for starters
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
Drifting
Joined: Sep 2010
Posts: 1,412
Likes: 50
From: Laguna Niguel California
Many, many years ago the same happened to my '75. I removed the tach, looked at the circuit board and found a burned out resistor. I soldered in a new one and it's been fine for the last 25 years. Take a look.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Corvettejet..
In almost all cases the issue is the board. I would bypass the filter for testing.. See if the tach works.
Then I would pulll the tach connector from the back of the tach and test it for power and ground. I would then test continuity from the dash connection to the connector the filter plugs into. If you have continuity then your issue is more than likely the tach board or the movement.
The other day I got to thinking, there is a way to find out if the board (or movement) is dead...
If you have the tach in your hand and apply 12 volts and ground to it..
You then use a jumper wire and attach it to the signal terminal... quickly tap the other end of the jumper to the 12 volts terminal with power and the tach should show upward movement.. If you get no movement, you should consider replacing the board.
75-77
78-82
Corvette Tachometer Board Installation Instructions 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=252
Corvette Tachometer Testing, Removal, Board Installation, Video Link 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=290
For the 75-77 tach's..
Corvette Left Hand Dash Pad Removal Made Easy 1968-1977
1978-1982
1975-1977
Thank You,
Willcox Inc.
In almost all cases the issue is the board. I would bypass the filter for testing.. See if the tach works.
Then I would pulll the tach connector from the back of the tach and test it for power and ground. I would then test continuity from the dash connection to the connector the filter plugs into. If you have continuity then your issue is more than likely the tach board or the movement.
The other day I got to thinking, there is a way to find out if the board (or movement) is dead...
If you have the tach in your hand and apply 12 volts and ground to it..
You then use a jumper wire and attach it to the signal terminal... quickly tap the other end of the jumper to the 12 volts terminal with power and the tach should show upward movement.. If you get no movement, you should consider replacing the board.
75-77
78-82
Corvette Tachometer Board Installation Instructions 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=252
Corvette Tachometer Testing, Removal, Board Installation, Video Link 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=290
For the 75-77 tach's..
Corvette Left Hand Dash Pad Removal Made Easy 1968-1977
1978-1982
1975-1977
Thank You,
Willcox Inc.
Last edited by Willcox Corvette; May 22, 2014 at 09:35 PM.
Heel & Toe
Joined: May 2014
Posts: 18
Likes: 0
From: Glen Lake MI
Corvettejet..
In almost all cases the issue is the board. I would bypass the filter for testing.. See if the tach works.
Then I would pulll the tach connector from the back of the tach and test it for power and ground. I would then test continuity from the dash connection to the connector the filter plugs into. If you have continuity then your issue is more than likely the tach board or the movement.
The other day I got to thinking, there is a way to find out if the board (or movement) is dead...
If you have the tach in your hand and apply 12 volts and ground to it..
You then use a jumper wire and attach it to the signal terminal... quickly tap the other end of the jumper to the 12 volts terminal with power and the tach should show upward movement.. If you get no movement, you should consider replacing the board.
75-77
78-82
Corvette Tachometer Board Installation Instructions 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=252
Corvette Tachometer Testing, Removal, Board Installation, Video Link 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=290
For the 75-77 tach's..
Corvette Left Hand Dash Pad Removal Made Easy 1968-1977
1978-1982
1975-1977
Thank You,
Willcox Inc.
In almost all cases the issue is the board. I would bypass the filter for testing.. See if the tach works.
Then I would pulll the tach connector from the back of the tach and test it for power and ground. I would then test continuity from the dash connection to the connector the filter plugs into. If you have continuity then your issue is more than likely the tach board or the movement.
The other day I got to thinking, there is a way to find out if the board (or movement) is dead...
If you have the tach in your hand and apply 12 volts and ground to it..
You then use a jumper wire and attach it to the signal terminal... quickly tap the other end of the jumper to the 12 volts terminal with power and the tach should show upward movement.. If you get no movement, you should consider replacing the board.
75-77
78-82
Corvette Tachometer Board Installation Instructions 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=252
Corvette Tachometer Testing, Removal, Board Installation, Video Link 1978-1982
http://willcoxcorvette.com/repairand...lp.php?hID=290
For the 75-77 tach's..
Corvette Left Hand Dash Pad Removal Made Easy 1968-1977
1978-1982
1975-1977
Thank You,
Willcox Inc.
Redboat
Last edited by Redboat; May 22, 2014 at 10:29 PM.
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Burning Brakes
Joined: Feb 2012
Posts: 925
Likes: 7
I freely admit to knowing absolutely nothing about a non-mechanical tach, so don't shoot me. If the needle moves the wrong way, is it possible that 2 leads are reversed?
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
You might try loosing up the nuts on the back of the back and then re-tighten them. If the tach needl still moves backwards then you do need a board.
Willcox
5th Gear
Joined: Apr 2014
Posts: 5
Likes: 0
First time posting, sorry if you've covered it already somewhere on the forum but i can't seem to find a link with the same problem I'm having, i have a 77 that i just bought and the tach doesn't work below 2800 but seems to work above 2800. The engine was replaced with a crate engine at some point. Just wondering where to start? Also when i shut the car off it pegs the needle far right if that helps.
I did try hooking the wire that goes to the filter directly to the distributer the tach pegs to the right.
Thank you