• 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Tach No Longer Working
#1
My tach was working when I first started the restoration, but sometime since it has stopped. What would be the proper troubleshooting steps? Could it just be a fuse issue? Car isn't drivable at the moment (need tires) so I don't know if the speedometer is working or not.

'73 "Q-Code" Mach 1
[Image: Mt7Cz.png]
|351C-4V|Holley 600CFM|Edelbrock Manifold|Unknown Cam|10:1 Pistons|Hooker Longtubes|Glasspacks|C4 Auto|Unknown Gears|

Cold Start And Run Video: http://www.youtube.com/watch?v=Kqr4NVCHxBk
  Reply
#2
Ouch

I would start with making sure all your connections are good..... car starts with no problems?


[Image: 1_14_01_12_10_54_29.png]

Ken

73 Convertible 302-4v-3spd yellow /white int

08 Bullitt 4.6-5 spd black/black int


All I ask is a chance to prove that money can't make me happy
  Reply
#3
Seriously try this bang the dash panel right under the tach with the engine running.

Mine sticks from time to time.

Baring that there is one connection behind the dash for the tach with a connector plug, you could swap it out for another if yours is dead

If you do swap it you need to take the entire drivers side dash apart to get to the tach for replacement
  Reply
#4
whitesoc;11305 Wrote:Ouch

I would start with making sure all your connections are good..... car starts with no problems?

Yeah, car starts fine. The needle jumps around but that might just be from vibration.

72HCODE;11334 Wrote:Seriously try this bang the dash panel right under the tach with the engine running.

Mine sticks from time to time.

Baring that there is one connection behind the dash for the tach with a connector plug, you could swap it out for another if yours is dead

If you do swap it you need to take the entire drivers side dash apart to get to the tach for replacement

Alright, I'll trying banging on it next time I have it running.

'73 "Q-Code" Mach 1
[Image: Mt7Cz.png]
|351C-4V|Holley 600CFM|Edelbrock Manifold|Unknown Cam|10:1 Pistons|Hooker Longtubes|Glasspacks|C4 Auto|Unknown Gears|

Cold Start And Run Video: http://www.youtube.com/watch?v=Kqr4NVCHxBk
  Reply
#5
Does the car start and run? If it does the tach has not burned open so H Code is right. If tries to start until you release the key from the start to the run position you probably have a problem with the tach or tach wiring. The tach is in series with the run circuit (not one of Ford's better ideas). If the meter movement in the tach sees too much current the coil in the movement burns open and the car with not run. It will start as long as the key in the start position because there is a splice connection at connector C-216 (the gauge feed harness connector at upper firewall, driver's side). This is wire number 16 and is red with light green stripe. The power is provided from one of the two small connections on the starter solenoid as long as the starter relay is engaged (the key is in the start position). The tach side of the circuit has a current limiting resistor wire as part of the circuit. The wire number is 16. It is a small diameter and is also red with a light green stripe on it. It provides power to the coil when the key is in the run position. To test, use a voltmeter to check for voltage with the wire (red and light green) removed form the "BATT" small connection on the coil and the key in the run position. If you have voltage the tach is not open. Sorry I've become long winded. Just trying to help.

Chuck
  Reply
#6
Have you added an MSD box or equivlant?The tach will not work if you add one of these with out an adaptor.

[Image: 16kuyc0.jpg]
  Reply
#7
FastE;11389 Wrote:Have you added an MSD box or equivlant?The tach will not work if you add one of these with out an adaptor.

I found this out the hard way, the tach still worked but it was about 2000 rpm off. It just gave me an excuse to buy an aftermarket tach and just hook it up straight to the msd box.

[Image: 25rnz1y.jpg]

~Buddy
  Reply
#8
yes when using the MSD box remember to use the Tach adapter from MSD to use the factory tach properly.

also when you bang the dash don't knock out tyson, just give it some angry love.
  Reply
#9
72HCODE;11417 Wrote:yes when using the MSD box remember to use the Tach adapter from MSD to use the factory tach properly.

also when you bang the dash don't knock out tyson, just give it some angry love.

The tach adaptor PN is 8920 (current driven type, Ford)

Chuck
  Reply
#10
c9zx;11346 Wrote:Does the car start and run? If it does the tach has not burned open so H Code is right. If tries to start until you release the key from the start to the run position you probably have a problem with the tach or tach wiring. The tach is in series with the run circuit (not one of Ford's better ideas). If the meter movement in the tach sees too much current the coil in the movement burns open and the car with not run. It will start as long as the key in the start position because there is a splice connection at connector C-216 (the gauge feed harness connector at upper firewall, driver's side). This is wire number 16 and is red with light green stripe. The power is provided from one of the two small connections on the starter solenoid as long as the starter relay is engaged (the key is in the start position). The tach side of the circuit has a current limiting resistor wire as part of the circuit. The wire number is 16. It is a small diameter and is also red with a light green stripe on it. It provides power to the coil when the key is in the run position. To test, use a voltmeter to check for voltage with the wire (red and light green) removed form the "BATT" small connection on the coil and the key in the run position. If you have voltage the tach is not open. Sorry I've become long winded. Just trying to help.

Chuck

Yes, the car starts and runs fine.

FastE;11389 Wrote:Have you added an MSD box or equivlant?The tach will not work if you add one of these with out an adaptor.

No box, just installed a Pertronix Ignitor. I am aware about the tach issue with the boxes, though.

'73 "Q-Code" Mach 1
[Image: Mt7Cz.png]
|351C-4V|Holley 600CFM|Edelbrock Manifold|Unknown Cam|10:1 Pistons|Hooker Longtubes|Glasspacks|C4 Auto|Unknown Gears|

Cold Start And Run Video: http://www.youtube.com/watch?v=Kqr4NVCHxBk
  Reply
Share Thread:  


Possibly Related Threads...
Thread Author Replies Views Last Post
  wiper motor not working John J 5 274 07-24-2018, 08:51 PM
Last Post: John J
  Pertronix work with factory tach? Tucaz520 3 299 05-22-2018, 11:50 AM
Last Post: delawarebill
  Dash lights working!!! scgamecock 1 307 03-12-2018, 06:50 AM
Last Post: midlife
tach 71 Mach tach stopped working danoreilly 2 552 08-05-2017, 09:44 AM
Last Post: Steve73QMach1
  Turn signal not working waterlife 1 421 03-28-2017, 07:35 PM
Last Post: midlife
  Erratic tach 1hotboss 7 810 09-04-2016, 01:47 PM
Last Post: 1hotboss
  fan motor not working John J 14 2,131 04-13-2016, 08:18 PM
Last Post: tatkinson@yousq.net
  Back up lights not working tatkinson@yousq.net 13 1,524 04-09-2016, 08:36 PM
Last Post: midlife



Users browsing this thread: 1 Guest(s)