Tach just stop working
Drifting
Joined: May 2008
Posts: 1,505
Likes: 7
From: Jacksonville FL
On my 80 the tach gets the RPM from the distrubitor via a small connector on the distributor. If you open the hood the part it connects to should be pointing towards the drivers side. I believe its the connector on the far right side. The one on the left is the power to the distributor.
Thread Starter
Pro
Joined: May 2004
Posts: 712
Likes: 4
From: caraquet N.B Canada
It was working fine until i shut the engine and when i started again i had to rpm reading. I disconected the RPM connector on the timmer just to make sure it was not loose and everything seems OK. Is there a way to check the tach to see if it work?
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Try plugging your tach wire in direct to the distributor bypassing the radio cap or tach filter first but it sounds like you have lost power or ground to the tach. Have you checked fuses ?
Heel & Toe
Joined: Mar 2017
Posts: 22
Likes: 0
tach stuck at 2000
So which fuse would it be that would affect the tach's ground and cause it to 'stick' at 2000 rpm?
I have an '80 C3 Coupe. 88,000 miles. Tach was working fine when I bought the car used in Jan. and only driven it about 100 miles since.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
You tach has a pwoer wire...a ground wire and a signal wire from the distributor.
DUB
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Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
If the issue is still there, then I'd remove the tach from the car and test the clips in the instrument housing. Test the positive clip using a ground other than the ground clip.. then test the ground using a different power source... this will eliminate a false positive.
This PDF file will walk you through it.... If you get to the end and the tach still is not working, then replace the board.
http://repairs.willcoxcorvette.com/w...-1978-1982.pdf
If you want to send your tach into us, we can test it too.. that's not an issue... and it will eliminate a bunch of testing for you. https://willcoxcorvette.com/corvette...-service-75-82
Willcox
Heel & Toe
Joined: Mar 2017
Posts: 22
Likes: 0
Odd Happening / resolution of issue with Tach
Now it's just a matter of getting the engine coolant temp gauge working, and no, the 'ground out' the connection wire doesn't seem to affect the gauge that's stuck at about 110 degrees. NOT helpful.
I may have a local garage that works on vintage cars check/do diagnosis and give me a quote. I am not a mechanic, do not have many tools nor a lift, etc.
But the TACH issus is solved. I am not sure how the fuse popped out of its own accord.
Last edited by BobM1980RedCorvette; Aug 25, 2017 at 11:54 AM.
Instructor
Joined: Jun 2015
Posts: 193
Likes: 34
From: Ohio
Im suddenly having problems with my tach not working as well. Even after installing a new tach board from Willcox it stays stuck at 5500 rpm. I verified power, ground, and tested the continuity of the signal wire as per Willcox's instructions and all are fine. It does not have a tach filter. If the instrument fuse was bad none of my gauges would work correct?
Last edited by Heus; Aug 27, 2017 at 08:17 AM.
Heel & Toe
Joined: Mar 2017
Posts: 22
Likes: 0
Gauge Fuses / Tach
Im suddenly having problems with my tach not working as well. Even after installing a new tach board from Willcox it stays stuck at 5500 rpm. I verified power, ground, and tested the continuity of the signal wire as per Willcox's instructions and all are fine. It does not have a tach filter. If the instrument fuse was bad none of my gauges would work correct?
In my case what stopped working with fuse out were the Fuel Gauge, Tach, and I believe, Ammeter. The clock I believe still worked. The engine coolant temp is still NOT working and I'll have to get that checked (in my case, by a mechanic), as its problem is evently not fuse-related.
