Tach connection

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
S

Stangmeister

Member
Joined
Jun 9, 2016
Messages
22
Reaction score
0
Location
Bethlehem, PA
My Car
1971 Mach1 351C C6 Auto
I just bought a '71 Mach 1 with a dash tach not working. Upon pulling the dash out, I found that the tach has two wires with a two prong male/female plug. It was disconnected, and there is no matching plug under the dash to plug it into. I bought a matching two wire connector. Can anyone tell me how to make the under hood connection? At the coil? I assume it is a simple hot/ground connection.

 
Welcome!

It is not a simple hot/ground connection. Power from the ignition switch (RUN-only signal) goes to the tach, then back out of the tach to the coil. The factory tach senses current to the coil.

Your mate to the tach plug should come out of the underdash harness where the headlight switch wiring breaks out of the underdash harness.

 
Here is a picture of a tach and gauge dash on the bench. Midlife is the most knowledgeable on the wiring for sure. If your car did not come with Tach and center gauges then someone probably did not change out the harness. My car had been hacked up so I pulled the entire dash and replaced the under dash and under hood harness to one that included all the options on the car, tach, gauges, air cond., convertible, convenience group, door speakers with AM/FM. Harness is not reproduced and is difficult to find in unmolested shape, took me about 10 months to find a good one.

Welcome to the forum.

CAM_0113.JPG

 
Welcome!

It is not a simple hot/ground connection. Power from the ignition switch (RUN-only signal) goes to the tach, then back out of the tach to the coil. The factory tach senses current to the coil.

Your mate to the tach plug should come out of the underdash harness where the headlight switch wiring breaks out of the underdash harness.
Click to expand...
 
Thanks for the replies! It did come with all dash guages, and it looks like all original wiring. I'll look for a connector in the headlight harness first and go from there. I'll advise when I find the fix.

 
If your car runs, and has the original wiring harness for tach and gauges, someone bypassed the tach by running a jumper across the two tach terminals in the harness. Disconnecting the tach also disconnects the coil from the ignition switch. If someone did disconnect the tach and jumper the connector it is likely because the tach is not working and would not provide the connection.

If that is the problem contact Rocketman in the Forum Marketplace for a solution.

 
If your car runs, and has the original wiring harness for tach and gauges, someone bypassed the tach by running a jumper across the two tach terminals in the harness. Disconnecting the tach also disconnects the coil from the ignition switch. If someone did disconnect the tach and jumper the connector it is likely because the tach is not working and would not provide the connection.

If that is the problem contact Rocketman in the Forum Marketplace for a solution.
Click to expand...
Welcome. If this is the case it would explain why you cannot find the connector as they probably cut it out and connected the two wires together.

 
Welcome from Oklahoma.

I wish there was a way we could move the tach part of this thread to another and keep your welcoming separate...

Ray

 

Similar threads

73inNH
Hunting a voltage leak
Replies
18
Views
1K
giantpune
G
tashakes
WTB-under-dash harness side of gauges connector
Replies
1
Views
529
Doug's 73 Mach1
Doug's 73 Mach1
tashakes
Tach and gauges install and wiring done.
Replies
16
Views
2K
mrgmhale
mrgmhale
agraff55
71 Mach 1 - Stock Tach Question
Replies
12
Views
2K
70cobrascj
70cobrascj
PoFoMoCo
Sport Lamp Switch Pigtail
Replies
7
Views
837
PoFoMoCo
PoFoMoCo

Latest posts

Back
Top