Tachometer
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
The next thing that is easiest to check is the connection to the distributor.
It's not unusual for the tach driver board to fail, but you have to remove the cluster to examine it. The used tach that I bought had a very obvious burned etch on the board. If you need a new one, buy one from Willcox. They re-designed the board so that it only uses 1 IC instead of the several used on reproduction boards (welcome to the 21st century). You could check the Willcox website to see if there are any troubleshooting procedures that you can do before removing the cluster.
BTW, the gauge illumination is a different circuit so whether that works or not will not affect the tach operation.
Rick B.
It's not unusual for the tach driver board to fail, but you have to remove the cluster to examine it. The used tach that I bought had a very obvious burned etch on the board. If you need a new one, buy one from Willcox. They re-designed the board so that it only uses 1 IC instead of the several used on reproduction boards (welcome to the 21st century). You could check the Willcox website to see if there are any troubleshooting procedures that you can do before removing the cluster.
BTW, the gauge illumination is a different circuit so whether that works or not will not affect the tach operation.
Rick B.
Le Mans Master
Joined: Sep 2002
Posts: 5,236
Likes: 898
From: Myrtle Beach SC
Tach Boards
Instructor
Joined: May 2011
Posts: 191
Likes: 1
From: Orange Ca
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,852
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Does it go to zero, or is it showing a reading?
The tach on your car works off three things; power, ground and signal. If the tach is getting power and ground and if the board is good it will go to zero when the key is turned on. If this is what you are seeing, then go to the tach filter and bypass it.. see if the tach works.
See if the tach works. If it works then you need to replace the filter. If it fails to work then you should go to the pages listed below. I have a ton of info on the site on how to diagnosis your problem.
Tach Technical pictures can be found here: http://willcoxcorvette.com/advanced_...&keywords=tach
Corvette Tachometer Testing, Removal, Board Installation, Video Link 1978-1982
Corvette Speedometer and Tach Housing Removal Instructions 1978-1982
Or you can search all the "Help and Repair" files for tach by clicking on this link..
http://willcoxcorvette.com/advanced_...s=tach&x=0&y=0
If you need to install the tach board, I have a long running thread with video links on how to do this as well.
Willcox
