Tach Question 1975
Thread Starter
Heel & Toe
Joined: Jul 2023
Posts: 16
Likes: 0
Tach Question 1975
Ok, I have a question. Bought a 75 last year. Tach didn’t work at all. I did a refresh on the inside and while in the dash, I replaced the whole tachometer from Corvette America. When I installed the tach, it would move at startup (jump to like 500). Then no movement. I replaced the tach filter today. No change - only slight movement at startup like before. Any suggestions?
Le Mans Master
Joined: Jan 2001
Posts: 6,713
Likes: 1,372
well, before tearing into I would get a portable tach (I have an old dwell meter/tach somewhere) or an old gm tach at the boneyard to see if the signal is getting through. that's what I did before converting to a 76 electric tach. Several gm cars had electric tachs..... a friend of mine just got one because he was there and I borrowed for this testing.....
I *suspect* that you could hook up an old dwell/tach meter to the installed tach leads to check (but I don't really know???)
SO - just an idea before having to tear the dash apart ...... 20/20 hindsight and whatnot, but if you pull it out..then test it before reinstalling in the dash.
I *suspect* that you could hook up an old dwell/tach meter to the installed tach leads to check (but I don't really know???)
SO - just an idea before having to tear the dash apart ...... 20/20 hindsight and whatnot, but if you pull it out..then test it before reinstalling in the dash.
Race Director
Joined: Nov 2006
Posts: 13,178
Likes: 7,781
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
OK, electric tach is pretty simple, power, ground and signal wires.
your tach does move, so you must have power and ground. But how good are the connections? Easy enough to test the signal wire with a ohm meter although you might need a friend to hold one test lead. If wiring checks. Clearly you got a bad one.
your tach does move, so you must have power and ground. But how good are the connections? Easy enough to test the signal wire with a ohm meter although you might need a friend to hold one test lead. If wiring checks. Clearly you got a bad one.
