Tachometer

Mark
Connected the wiring back together as it's was meant to be, but it still doesn't work.
I was wondering if you knew what kind of ohms reading Im am meant to get on the back of the gauge.
Dennis

Did you check the wire on the coil side?

Dennis, you don't have an aftermarket ignition, do you? If you have an MSD electronic ignition, for example, the tach won't work without the special adapter. No big deal, and it isn't expensive, but it doesn't work without it!

Has it always not worked? Or has it recently decided to "rest"?

Charlie, Dennis,

Even if you do have a tach adapter, they often fail. Sometimes they go 'in and out' before finally kicking the bucket. This is what happened to mine.

I've read on this forum of a guy getting new ones that didn't work, and changing it 3 times before he got a good one!

Michael

We need to know of your ignition system..by the way..I have had 3 8920 tach adapters burn. I have one back from repair @ MSD...but I am afraid to install it. I would not recommend putting one under your dash!

Charlie/Micheal
I have had the car for only a few months , the tacho has never worked at all.
The wiring on the back looks likes it's been tampered with, I went on the panteraplace
web site and found out how what the wiring should be like but it doesn't show you the
back of the tacho just a drawing of the connection plug.
Dennis

If you go to the DeTomaso forum, DeTomaso@realbig.com and ask the tach question, I'm sure Bill Taylor (SOBill Taylor) will give you a good answer.
Art

Dennis,

can't help until we know the make-up of your ignition. Is it stock, or is it aftermarket?

your friend on the DTBB, George

George the ignition is stock!
Don't know why they tampered with the wiring.
Dennis

Dennis,

I've not had to work on my tach & I am finding there is not much info available regarding the wiring connections behind the tach. I only have a small version of the Pantera wiring diagram & I am finding my eyes are no longer capable of seeing detail that small. I need to invest in one of the larger versions.

The basics are to verify the wiring behind the tach is connected properly and verify there is 12 VDC to the power connection at the back of the tach when the key is in the run position, that you have a good ground, etc.

Assuming the wiring is correctly connected behind the tach, and the supply voltage and ground are good, the next step is to verify that the tach is connected to the neg terminal of the coil.

The ignition coil has 2 small terminals on it, one marked "+" and one marked "-". The plus terminal has wires landed on it from the key and from the starter solenoid.

The negative terminal also has 2 wires landed on it, a blue wire from the distributor and a blue wire with black stripe from the tach. If that blue/balck stripe wire is disconnected from the coil, the tach will not function.

The tach is an electronic device; therefore a simple resistance check may OR may not indicate a problem. If I were to test the tach, I would remove it from the vehicle, make known good battery & coil connections between the tach & the vehicle using short lengths of wire and then start the car & see if it works. Its like using the car as a test bench/signal generator.

Good luck Dennis, let me know if I can be of further assistance.

your friend on the PIBB, George

George
Thanks for your help again!
Your mate from AUS
Dennis

Downunder, I have an extra tach if you confirm that yours is toasted. Before I'd buy and ship another one, though, I'd check to see if you can get yours repaired locally.
I installed a MSD ignition and wired it wrong to the tach. Local "experts" told me the MSD Tach Adapter was pretty tough and probably not the problem. This turned out to be total Bull$#!+ as these posts confirm. I purchased another tach and then a new Tach Adapter which solved the problem. I know this tach is OK because it was in the car when I got it working. I then switched back to the original tach which worked fine as well.
I don't know if there are different tachs. Mine matches and works correctly in a '72. Yours may be different. The indicator lights may not be the same in a later car.
Anyway, it may be an option.
Mooso.

Mooso
Thanks for the option I will definately keep
you in mind.
Got to do more fault find I think, order of elimation stuff.
Dennis

Can anyone post a photo of the back of tachometer so I can check if my wiring is ok!
Also George Pence said it was possible to use the tacho out of the car and test it with the coil, can anyone tell me the exact procedure.
Dennis....confused

Dennis,
The tach can be tested out of the dash and that might be the best way to determine what is the problem.
This weekend I will check the wire colors on my 1972 and let you know what to do.
Basically there should be a +12 Volt connection that would be "on" when the ignition switch is on. A ground connection is also required, usually black lead. Then there is the connection that measures the engine speed, that connection needs high voltage pulses that are generated at the ignition coil. The connection to the coil has to be to the side with the points. This is assuming stock ignition as you said you have.
These three connections are the basics and should make the tach work. You can make all of these connections near the coil with temporary leads to test.
Monday, at the latest, I will post the colors of the proper connections (I don't drive my Pantera to work) or if there are other wires that must be connected for operation.

Jon3616
Thanks for your help can't what to hear from you soon!
I don't want to jump to the wrong conclusion about the tacho and find out it's something else, can be very expensive excercise.
Dennis

Dennis,
The color wires that are important to the Tach operation are:

Light Blue and White in black sleeve are connected together and supply +12 volts.

Black wires are ground attached to the tach case.

Dark Blue with Black stripe, (has a red mark on it) wire is the points wire or the wire that provides the pulses for the tach for RPM.

All other leads are for the indicator lights which I removed for the picture. (I added the green dots which are marks for the lights)

You can test the tach at a convenient place at the firewall were the electrical parts are on the passenger side. +12 volts is there via the battery connection to the solenoid, Ground is the chassis, points is the wire that connects to the points.
I assume that the factory ignition system is complete IE capacitor in the distributor.

Jon3616
Thanks for confurminig the wiring for me that takes all the guess work out!
Now I can connect and following the correct wiring back to the coil...
Thanks agian for your help
Your mate from AUS
Dennis

quote:

Originally posted by Jon3613:
Dennis,
The color wires that are important to the Tach operation are:

Light Blue and White in black sleeve are connected together and supply +12 volts.

Black wires are ground attached to the tach case.

Dark Blue with Black stripe, (has a red mark on it) wire is the points wire or the wire that provides the pulses for the tach for RPM.

All other leads are for the indicator lights which I removed for the picture. (I added the green dots which are marks for the lights)

You can test the tach at a convenient place at the firewall were the electrical parts are on the passenger side. +12 volts is there via the battery connection to the solenoid, Ground is the chassis, points is the wire that connects to the points.
I assume that the factory ignition system is complete IE capacitor in the distributor.

Nothing like a photo to accompany your description!

Way to go Jon! EXCELLENT!!