Tach quit; most likely suspect?

[RC92234]

Tach has been working fine since I got the car 3 years ago. Literally nothing happened in between the last time it ran with the tach working and now besides it sat quietly in the driveway. Sun went up and sun went down 12 or so times. Wind blew. Nada.

Starts and runs fine -- just no response from the tach. Thoughts?

 

[Sheriff41]

Did you try reseating the wires on the coil?

 

[c9zx]

Mechanically "stuck". If the meter movement goes open, no start/no run. I'm assuming factory tach and wiring. Chuck

 

[TheRktmn]

Faria Tachs are notorious for failing mechanically. The 'movement' is a bunch of stacked metal plates epoxied between two BIG magnets. The epoxy dries out and things shift.

 

[delawarebill]

my '73 did the same thing. didn't move. Sooooo with engine runnng i smacked the hell out of the top of dash. it was stuck and now working.

 

[SteveO_71]

As mentioned in posts above, must be some kind of short or stuck movement. If the tach was 'open' your car wouldnt start since the tach is part of the starting circuit.

 

[RC92234]

Thanks y'all -- I'll try giving the dash a good smack, which is hilarious because that's what I have to do for my '95 Lexus LS400 for *both* the tach and speedo regularly. It was much warmer two weeks ago when I last drove it and we now have nice and cool evenings, so fingers crossed this is it. However... that may have to wait until the dash pad is reinstalled (for speedo cable replacement among other things).

And thanks for confirming that if the wiring went wrong, the car wouldn't start. That was what puzzled me!

 

[midlife]

There are 2 basic failure modes for the Ford tach: the input transformer blows, not allowing current to flow from the ignition to the coil and the second failure mode is as described above: the gauge guts fail, but the engine still runs.

 

[mrgmhale]

Replacing the tach with a rebuilt unit is an option, of course. RocketMan (RocketMan, stop reading this post, I do not want your head to swell up where you end up hurting yourself) has an excellent reputation for being able to help folks out of a tach jam. In our case, with our two 1973 Mustangs, both had idiot light laden instrument panels. The only analog gauges/meters we had were the speedometer and fuel gauge. I really wanted analog gauges, but did not want to install the center vertical bezel mounted analog gauges, as I was planning to use that area to mount our Garmin Drive 72 GPS/Backup Camera Display. So, I took an alternative path that worked out well for what I wanted to do. I purchased two Dakota VHX analog gauge instrument panel kits. They were costly, perhaps more than it would have been to just find some oem instrumentation and adapted as needed.

https://www.dakotadigital.com/index...t_id=922/category_id=434/mode=prod/prd922.htm

It turns out those Dakota display units have worked well for us in both Mustangs. Depending on what your oem configuration is, going the Dakota route may not make sense. In that event I suggest you look at what RocketMan offers and see what he suggests (yeah, me tooting his horn for him.). In fairness, I have never had him do tach or clock work for us, but I have purchased several of his headlight relay kits, and found them to be well made, and they worked perfectly. I know I could have hodged together a headlight relay system on my own, and it would have worked fine,. But, there is something to be said for investing into a product that has been built, and operating in many other cars, much less is a clean installation with no splicing or wire cutting/soldering. Thus, why I opted to use his relay solution as opposed to rolling my own, so to say.

Based on my experience with what he has created, plus what I read from others who have used his services for clocks and tachometers, I am certain he will be able to come up with a great solution for you.

https://www.rccinnovations.com/index.php?show=menu-tach-all