Dead tach 1981

[Charlie P.]

I'm now getting to addressing some glitches in my '81. I see the 78-82 group doesn't get much action on the TDB. I hope there are some experts out there who can help. First glitch is the tach. Where should I start looking to determine cause of non-functioning tach? Of course I am hoping it is not the tach itself, but in the sending circuit.

Thanks,
Charlie

[Paul O.]

Re: Dead tach 1981

Charles try this old post you can check the archives there may already be several post of the same problem. Hope this helps. Also when you are looking at the board if as you did have the years listed to the far left if you left mouse click on the years only those years will then be listed.

https://www.forums.ncrs.org/showthread.php?t=60071&highlight=tach+problems&uid=5954

Paul 18046

[Joe L.]

Re: Dead tach 1981

I'm now getting to addressing some glitches in my '81. I see the 78-82 group doesn't get much action on the TDB. I hope there are some experts out there who can help. First glitch is the tach. Where should I start looking to determine cause of non-functioning tach? Of course I am hoping it is not the tach itself, but in the sending circuit.

Thanks,
Charlie

Charlie-----


First place to look is the tach filter which is located on a bracket on the passenger side valve cover. Very often, the wire on one end of the filter will be broken off.

[Joe R.]

Re: Dead tach 1981

Sorry Charlie,

If it's not the broken wire trick you will most likely have to replace the circuit board behind the tach. Not a big problem with the later Corvettes as it comes out from the front without removing ALL of the dash.

Several vendors and E-bay sellers advertise that board at a very reasonable cost.

Easy Saturday afternoon fix.

JR

[Tom R.]

Re: Dead tach 1981

Sorry Charlie,

If it's not the broken wire trick you will most likely have to replace the circuit board behind the tach. Not a big problem with the later Corvettes as it comes out from the front without removing ALL of the dash.

The second place to look is the tach board. It is estimated that 90 percent of the time, its the tach board. Consider, its been there for 30 years and components start to give way along with the copper paths that crack or burn out. The 80 had the best design for tach boards among those early years of HEI but its still thirty years. I've attached an article published in the defunct Corvette Enthusiast that describes the problems and cures for 1978-82.

Several vendors and E-bay sellers advertise that board at a very reasonable cost.

Wilcox Corvette was the second Corvette distributor to make the boards here and offers some nice videos of how to go about it. John Gardner made them in the USA first, privately (see article) at a reasonable cost and was the individual that was able to problem shoot many of the boards that were made overseas and were troublesome. The board in my 78 Pace Car is a Gardner board.

http://willcoxcorvette.com/instructions/tach_board_install_78-82_new_3.pdf

http://www.hunt4cleanair.net/Articles/tachboards.pdf

[Charlie P.]

Re: Dead tach 1981

I think between your comments and references I should be covered. Thanks much to all,
Charlie