I have an 80 L/82 that I just got.
I noticed that the tach is stuck at about 3 grand.
I checked the connection on the distributor and it is hooked up.
I suspect it is the board, any other suggestions?

 

Make sure the wire from the distributor is plugged in to the tach filter and the filter is plugged in to the firewall lead. If the tach filter is connected to the distributor and not to the firewall connector you won’t have a signal coming in to the tach. If it is plugged in at the firewall then take the wire loose at the distributor and go to the back of the dash connector. Remove the plug and make sure the wire is good from the distributor to the tach connector. If this wire is good (Run a continuity test from the distributor to the connector plug in). The tach filter wire I think is white and runs from the distributor to the firewall of the car where it plugs in to the main dash harness. The filter also looks like a capacitor and will either bolt to the intake on the drivers side and/or a bracket on the back of the engine based on what year the car is.

Once you establish the signal wire is good, test to make sure you have a good ground at the connector and a good 12 volts.

You could have a problem in the wiring where the tach is not getting power too!

If you need more help on this you can email me direct at Willcoxcustomerservice@Willcoxcorvette.c om

If you need the tach board, we have them and they are real easy to install. Here is the link on the forum special side. http://willcoxcorvette.com/product_i...ducts_id=25779

Happy Holiday's

Willcox Inc

 

Make sure you have power going to the tach.If the power is interrupted like turning the key off at 3k the needle will remain there.

 

Thanks for the reply.
I have sent you an email.
I do have power from the dist to the capacitor.

 

Buy the replacement circuit board & you're done!

Almost everyone who has ever bought a used 1980-82 C3 has this very same problem. It is usually the first (of many) repair/mods made.

 

#6
jtg7582
Junior Member



My Corvette Photos
Member Since: Jan 2006 Have Tach Problems 1975-82, Please Read

--------------------------------------------------------------------------------
Hi, My name is John Gardner,


and you are NOT a supporting vendor..if you want to sell your stuff then you need to pay to be one...feel free to give advice but do not bash other products or try and sell your stuff here.

-pewter99

 

Do you not have to pull the dash to check the circuit board, if so I would check all else.

 

oh God no.

To pull the tach board takes 5 minutes.

Sit in the drivers seat, look at the dash, get a screw driver (maybe hex or torque screws I think) ....Take off the clear window bezel sheild (covering the speedo & tach) cover, remove bezel, carefully remove screws, pull tach out towards yourself, look at tach, notice how corroded the circuit board looks on the backside, remove old stinky board by a couple of few screws, install new board correctly (one from the fellow above ^^^) or equivalant, verify needle to zero if needed, GENTLY!!!! The needle is very fragile & brittle.
Reinstall everything.

It really is that easy.

 

Probably won't be your solution, but my 78SA tach was stuck, too. Was getting ready to change the board out. Took off the clear window and gave the needle a little nudge. Started working again.
Two other Vettes I have did need new boards. Had the old ones checked but both were un fixable.

 

Like Vette80regon stated, it's fast and simple on 78-82s.
But, I see you have a 76. You will need to do a little more work to get to the board. Yes, the cluster needs to come out.

 

Thanks for the info.
Let us know how much your tach boards are.

 

Several of us are waiting for you to give us the price on your modified tach boards...
Let us know!!!

 

Yep I was looking at that instruction and thinking "What's he nuts or something?"

It was a MAJPITA to get mine out .. and I got a bad circuit board to boot. So for three years now, my tach has been moving up & down, but it is thousands off from where it should be pointing.

 

I'm looking for a few 75-77 tach boards...anyone replaced theirs and wish to donate?

 

Is is model year dependent...75-77 must pull dash but 78-82 escape this PIA dis-assembly.

 

John Gardner is correct. I had bought a new Tach board for my 80. After installing it still was not working correctly. Called John on the phone and he instructed me on a few things to try. Still , tach not working. I sent my Tach off to John and within a few days had it back. After installing , tach works perfect. John knows his stuff on tachs. Dave

 

perhaps he is but he is not a supporting vendor and some of his information may not be 100% correct...

 

Guys... The OP has a 1980!

It's in the thread title and the first post.
80-82 is easy as any.

 

Thanks for getting my thread back on track.
I guess John got zapped, looks like some of his posting is missing in this thread.
I wasn't trying to stir up anything, just trying to get my tach fixed.
I can't get in contact with John.

 

Pewter99, So this is how it's run is it. I don't need this. See ya. Dave