Tachometer Troubleshoot
Thread Starter
Instructor
Joined: Mar 2008
Posts: 221
Likes: 0
From: Farifax Station VA
Tachometer Troubleshoot
Someone cut the Tachometer pigtails off at some point, and so I am trying to trouble shoot to see if the circuit board needs replaced and if the Tac will work.
-I am getting power to the Hot wire to the back of the Tac.
-But I don't think I am getting a single from the Distributor?
where does the wire comeout of the dist that goes to the back of the TAC?
-I am getting power to the Hot wire to the back of the Tac.
-But I don't think I am getting a single from the Distributor?
where does the wire comeout of the dist that goes to the back of the TAC?
Pro
Joined: Feb 2006
Posts: 718
Likes: 7
From: Jacksonville , NC
Your HEI distributor has a rectangular tab on the top/side of the distributor cap. Ther are three electrical plugs... one on the inside is for the wires from the distributor, one marked BATT the other TACH On my 80 the TACH wire is white and goes to a noise supressor then back into the wire bundle to the TACH. BATT is pink and should have 12 volts. Not sure if the 77 is exactly the same, but the distributor wiring shold be.
Pro
Joined: Feb 2006
Posts: 718
Likes: 7
From: Jacksonville , NC
I just checked the 1977 wire diagram and it should be a white or brown wire from the TACH terminal on the distributor straight to the tach. The other terminal on thedistributor shold be the pink hot wire that on the 77 went throught the radio noise capacitor. Might be someone with a 77 that can be more specific. I just finished rewireing my 80 and its a bit different but still should come from the TACH term.
1st Gear
Joined: Jul 2008
Posts: 1
Likes: 0
I have an 1980 and the tach wire is disconnected from the HEI. I found a brown wire that is not connected anywhere and it doesn't have a filter on it.
It seems to be the one that goes to the tach signal in the dash as I checked the continuity with an ohmmeter.
I am wondering if it's normal to have a brown tach wire since the 1980 service manual shows a white wire.
Also, I am wondering if I could get a similar wire with a filter on another model in a junkyard or if I need to order the part for a Corvette...
It seems to be the one that goes to the tach signal in the dash as I checked the continuity with an ohmmeter.
I am wondering if it's normal to have a brown tach wire since the 1980 service manual shows a white wire.
Also, I am wondering if I could get a similar wire with a filter on another model in a junkyard or if I need to order the part for a Corvette...
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
I have an 1980 and the tach wire is disconnected from the HEI. I found a brown wire that is not connected anywhere and it doesn't have a filter on it.
It seems to be the one that goes to the tach signal in the dash as I checked the continuity with an ohmmeter.
I am wondering if it's normal to have a brown tach wire since the 1980 service manual shows a white wire.
Also, I am wondering if I could get a similar wire with a filter on another model in a junkyard or if I need to order the part for a Corvette...
It seems to be the one that goes to the tach signal in the dash as I checked the continuity with an ohmmeter.
I am wondering if it's normal to have a brown tach wire since the 1980 service manual shows a white wire.
Also, I am wondering if I could get a similar wire with a filter on another model in a junkyard or if I need to order the part for a Corvette...
If you don't need an original looking unit, you can easily construct one with a couple dollars of radio shack parts. Here's the schematic:
And here's a pic of one of the several I have built in the past for fellow forum members:
Good Luck!
1977, 1980, alternator, brown, c3, corvette, diagram, filter, forum, schematic, tach, tachometer, troubleshoot, troubleshooting, vette, wire
