Problem with new tach boards? HELP!
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Joined: Jan 2005
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Problem with new tach boards? HELP!
Hello,
I have a 1979 C3 L48. The tach started acting up. When it should have been reading about 3000 rpm, it reads maybe 5000 rpm, but at 0 rpm it reads 0 rpm. So, I replaced the circuit board with one from Ecklers.
Then, the tach didn't work at all!! The needle didn't move regardless of RPM. So I returned that one and got a new board from Midamerica. Their board did not work at all either!!
After replacing the two new boards with my old one, it operates as before...it reads too high. I have checked the connections to the filter at the manifold, they are fine.
Any suggestions would be GREATLY APPRECIATED!!
Thanks in advance for any responses.
-Jim
I have a 1979 C3 L48. The tach started acting up. When it should have been reading about 3000 rpm, it reads maybe 5000 rpm, but at 0 rpm it reads 0 rpm. So, I replaced the circuit board with one from Ecklers.
Then, the tach didn't work at all!! The needle didn't move regardless of RPM. So I returned that one and got a new board from Midamerica. Their board did not work at all either!!
After replacing the two new boards with my old one, it operates as before...it reads too high. I have checked the connections to the filter at the manifold, they are fine.
Any suggestions would be GREATLY APPRECIATED!!
Thanks in advance for any responses.
-Jim
Drifting
Joined: Aug 2004
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From: Fayetteville NC
I read a post on the forum a few weeks ago that talked about these tach boards being grounded out once they're installed to the back of the tachometer (I think that's where it's located). Then the tach didn't work at all. That sounds like the problem you're having. This person thought he had received a bad replacement board which turned out not to be the case. I think he ended up using rubber washers when installing the board. I'm real interested in seeing what responses you get to this thread. I need to repair my electric tach in my '75 but am trying to diagnose my problem before I buy.
Instructor
Joined: Dec 2003
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From: Rio Medina Texas
I just replaced the board in my 77. It came with 3 insulating washers that go under the board next to the needle housing. The old board didn't need it because there were no contacts on the backside. The replacement board worked fine.
Team Owner
Joined: Apr 2001
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From: S.W. Ohio. . . . . . NRA Life Member
Hey, if any of you want the tach calibrated - I am just getting set up to do this.
I repaired electronic tachometers for C3 Corvettes at a GM contracted company... while they were still under warranty !!!!
But, I'm not old... damn you.
It's been 25 years since I did that type of work and am currently upgrading the wifes 1973 to a 1975 electronic version. So I have assembled the necessary test equipment to do the work myself.... thinking I could take on some extra work too.
I'll gladly look at 2 to 3 C3 Corvette electronic tachs for calibration adjustments only. I can't offer any repairs since I have no source for parts... yet. Will ask only for return UPS charges at this point
email me if interested.
I repaired electronic tachometers for C3 Corvettes at a GM contracted company... while they were still under warranty !!!!
But, I'm not old... damn you.
It's been 25 years since I did that type of work and am currently upgrading the wifes 1973 to a 1975 electronic version. So I have assembled the necessary test equipment to do the work myself.... thinking I could take on some extra work too.
I'll gladly look at 2 to 3 C3 Corvette electronic tachs for calibration adjustments only. I can't offer any repairs since I have no source for parts... yet. Will ask only for return UPS charges at this point
email me if interested.
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Joined: Jan 2005
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Originally Posted by soggybottomboy
I just replaced the board in my 77. It came with 3 insulating washers that go under the board next to the needle housing. The old board didn't need it because there were no contacts on the backside. The replacement board worked fine.
SUCCESS!!!! Thanks to the above post, my tach is now working. I tried it with and without the filter hookedup, and that did not help.
Ecklers had told me not to use the insulating washers...THEY WERE WRONG!! All three insulating washers must be used to make the circuit board work properly. The insulate the circuit board from making a connection with the tach housing. Unfortunately, two of the washers were too smal to fit over the tapered centering posts at the base of the mounting studs. The washers had to be drilled out to make them fit. This allows the circuit board to lay flat.
Thnak you all!!
