D
Don Bishop
Guest
Hello, I have a 1978 Corvette, my problem is with the tachometer, when the engine is started the needle pegs out and stays that way untill engine is turned off, anyone have a fix? Thanks Don
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- #2
C
C V Man
Guest
Sounds like it's shorting to ground or something...
...But I don't see what's funny about it.
(You posted in the humor mill)
C V Man
...But I don't see what's funny about it.
(You posted in the humor mill)
C V Man
- Joined
- Aug 29, 2001
- Messages
- 3,239
- Location
- Norcross, Georgia, United Stat
- Corvette
- 2017 Arctic White Grand Sport
My tach gave me fits when the 10amp gauge fuse blew. Change it and see if that has any effect.
Wtf?
Why is this in the Humor Mill?
Why is this in the Humor Mill?
Rain
Well-known member
That was my question....DRTH VTR said:
- Joined
- Aug 29, 2001
- Messages
- 3,239
- Location
- Norcross, Georgia, United Stat
- Corvette
- 2017 Arctic White Grand Sport
'Cause he's new, made a mistake and a moderator hasn't picked up on it and moved it yet.
Well it is kind of funny ..... I may have the same problem, but I think my motor is in bass ackwards............
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D
Don Bishop
Guest
so I messed up, no its not funny
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D
Don Bishop
Guest
because I messed up
The73vetteman
Well-known member
Hello Don,
I have no ideas about your tach - mine is just dead and will stay that way til I rebuild the dizzy - but I thought I'd take the opportunity to say Hi to the new guy.
We were all new here once, and we've all posted in the wrong place at some time I'm sure.
'73
I have no ideas about your tach - mine is just dead and will stay that way til I rebuild the dizzy - but I thought I'd take the opportunity to say Hi to the new guy.
We were all new here once, and we've all posted in the wrong place at some time I'm sure.
'73
Rain
Well-known member
The73vetteman said:We were all new here once, and we've all posted in the wrong place at some time I'm sure.
'73
I know I have!!!
Worst one was when a forum member suggested we post pics of our vettes..
I put like 4 or 5 up before I realized it was for the Callaway Forum! oops!
Looks like this one has been corrected - No foul no harm!
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- #12
T
theo
Guest
Don - the fact that your needle pegs out (I presume you mean at zero) is a good start.. It shows you are getting a feed to the tacho board. The board has three feeds - 12V, earth and a pulse from the distributor (the speed of this pulse is of course proportional to the engine spark, and is what tells the tacho circuit board how far to turn the needle).
There are two possibliities I can think of. You're either not getting the pulse or the circuit board is stuffed and can't read the pulse.
To check for the first possibility is the easiest. Look at the terminal marked "tach" on the distributor, it should be connected to a single wire that runs to the tacho "filter" (a little silver canister that is normally bolted to the inlet manifold). Check that the wires into and out of the filter are not broken or corroded (they break easily right where they go in). Follow the wire and check its plugged tightly in to the wiring loom at the other end. If you have a ohmeter you can check the continuity thru the filter by unplugging it at both wire ends and hooking up your meter - it should be about 15 - 20 kOhms. Also, to work properly, the filter case must be grounded. So check its bolted cleanly and tightly to the inlet manifold.
Of course all this is pointless if you have no filter, as many people seem not to. As long as you have a wire connected between the "tach" terminal on the dist and the plug into the loom, then the tacho should work. There's a lot of opposing views as to whether the filters are really necessary. As i understand it they are suppposed to filter out radio noise AND protect the tach circuit from voltage spikes. Some say you can run for ever without one, some say other wise. For me, since I have one and it works, I use it. Simple as that. Don't want to fry my new board.
So if everything checks out there, the problem is most likely with the board in the tacho. You can get a new version of this board from Redline http://www.redlineg.com/
This is where I got mine from - can't praise them enough for their help and advice..
But try and make sure it's not a problem closer to the engine fist, before shelling out for a new board and ripping the dash out! If you can get hold of another tacho gauge (some sort of aftermarket mechanic's style thing) you could hook it up on the "tach" terminal of the dist, to see if you are getting a signal. (This may not work" downstream" of the filter)
What you really need to make sure the filter works is an oscilloscope, but how many people have one of them to hand?
Good luck - Hope this helps!
There are two possibliities I can think of. You're either not getting the pulse or the circuit board is stuffed and can't read the pulse.
To check for the first possibility is the easiest. Look at the terminal marked "tach" on the distributor, it should be connected to a single wire that runs to the tacho "filter" (a little silver canister that is normally bolted to the inlet manifold). Check that the wires into and out of the filter are not broken or corroded (they break easily right where they go in). Follow the wire and check its plugged tightly in to the wiring loom at the other end. If you have a ohmeter you can check the continuity thru the filter by unplugging it at both wire ends and hooking up your meter - it should be about 15 - 20 kOhms. Also, to work properly, the filter case must be grounded. So check its bolted cleanly and tightly to the inlet manifold.
Of course all this is pointless if you have no filter, as many people seem not to. As long as you have a wire connected between the "tach" terminal on the dist and the plug into the loom, then the tacho should work. There's a lot of opposing views as to whether the filters are really necessary. As i understand it they are suppposed to filter out radio noise AND protect the tach circuit from voltage spikes. Some say you can run for ever without one, some say other wise. For me, since I have one and it works, I use it. Simple as that. Don't want to fry my new board.
So if everything checks out there, the problem is most likely with the board in the tacho. You can get a new version of this board from Redline http://www.redlineg.com/
This is where I got mine from - can't praise them enough for their help and advice..
But try and make sure it's not a problem closer to the engine fist, before shelling out for a new board and ripping the dash out! If you can get hold of another tacho gauge (some sort of aftermarket mechanic's style thing) you could hook it up on the "tach" terminal of the dist, to see if you are getting a signal. (This may not work" downstream" of the filter)
What you really need to make sure the filter works is an oscilloscope, but how many people have one of them to hand?
Good luck - Hope this helps!
Don Bishop said:
Sorry Don if it came off like I was making fun of your problem, poor judgement on my part. Sometimes these forums have a little twisted humor now and then.
Good luck and welcome - I'm certain you will find the answer here and whatever you do have a good time.
(I'm the one on the right)- Thread starter
- #14
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dbettner
Guest
Tach. Filter
I by passed my tach. filter and after starting the car twice my new circuit board burnt out so if you have a Tach. filter installed on your car at the factory then you need it dont take it off and try to by pass it if you do you will sooner or later burn out your tach circuit board a 60 to 80 dollar item depending on where you order it from.
If you change the filter and it still does not work then you need a new circuit board you can order them from Ecklers, Mid America or Corvette central prices very between the three.
Go to e-bay and check out the tachometer filter listed for sale.
I by passed my tach. filter and after starting the car twice my new circuit board burnt out so if you have a Tach. filter installed on your car at the factory then you need it dont take it off and try to by pass it if you do you will sooner or later burn out your tach circuit board a 60 to 80 dollar item depending on where you order it from.
If you change the filter and it still does not work then you need a new circuit board you can order them from Ecklers, Mid America or Corvette central prices very between the three.
Go to e-bay and check out the tachometer filter listed for sale.
Stallion
Well-known member
It might be the electric board where in your case you would have to take the dash off to rebuild. But, it might be just some circuitry, like was suggested. But, if he blew a fuse, then why would it get extra juice? Wouldn't it get none?
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