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!!

Like the saying goes: 'A picture is worth a thousand words!'

Michael

Jon,

Way to go!

I am absolutely too arthritic & stiff to lay on my back & work under the dash like that. Besides, my vision is so bad up close, I wouldn't be able to distinguish the steering column from the speedo cable. You are the man! I am printing your picture & saving it.

Now Dennis, get back with us & let us know how your tach tests, OK?

your friend on the DTBB, George

Now all I have to do is work on how to get my body under that spacious dash and flooring.
I can already feel my back hurting...
Thanks Guys

Dennis,

wish I were there to hand you the beers mate. One for you, one for me. another for you, two for me. another for you, three for me!

We'd have that tacho fixed before too long. Or at least we'd have a good time trying!

George

George
It's lucky for me im lying on the floor of the car don't have too far fall after all that drinking!
I've definitely got to make a trip over there!
Spare parts that the excuse!
I'll tell my wife look it's the only place to get the parts, you don't want me making a
mistake and getting the wrong parts cause they just won't refund me the money back!
Dennis

You know those american blokes, they would rob their own grandmother, best if you do business in person.

George

Don't see any points, looks like its magnetic type.
I have stock gauges and I just got the tacho back from the repair shop, they told me gauge is ok!
Were do I go from here.
If I sound confused thats cause I am.
Sorry about bad photo
Dennis

Dennis,
This is a variable reluctance or magnetic type .... there are no points. There must be an ignition system (box) that is in your car somewhere and you need to find it ….. or possibly this sensor can drive a coil directly but I doubt it. I don't recognize this configuration it might be a European design not common the U.S.
Follow the wires from the distributor and let me know where they lead to. (a pun)
I did not suggest you have the tach tested and I hope it did cost much … we weren’t ready for that step yet.

Dennis,

I don't recognze the dizzy. The late model Aussie Cleveland engines had an oem Bosch electronic ignition, none of us American blokes would recognize it, so I suspect that may be what we're looking at. I can't say whether or not there was a separate ignition module with the Bosch distributors, or if it is all contained within the dizzy.

FYI: The distributor hole in the block for the Bosch distributor is a different size than the hole for the breaker point distributors found in earlier Clevelands, therefore breaker point distributors & American Duraspark distributors don't fit Australian blocks designed for the Bosch distributor & vice versa.

However, so long as your ignition module is not producing multiple sparks (like an MSD) the tacho will work just fine hooked to the negative term of the coil.

We're back to where we were before, need to check that the tacho is getting 12 volts, has a good ground, and is connected to the neg terminal of the coil.

Your dizzy friend on the DTBB, George

Jon/George
Well I got the tacho back from the repairer, and they told me that the distributor is a magnetic type and that it should power the tacho with no problem.
When I got the gauge tested he told me that there was a positive supply and negative supply but on the back of the gauge but the negative earth on the gauge wasn't connected.
When he connected it he said the tacho worked fine, so I guess I have to work out if the negative supply is coming back to the gauge.
I'll keep you posted, thanks again for the help.
Dennis

It's fixed!!!!
Yes another Pantera adventure over with, only time till the next one begins.
Again thanks everyone for you help.
Dennis

Excellent.
Was it just a wire that had become disconnected or did you need some new wiring?

Dennis,

Don't leave us hangin'! Tell us what the culprit was, and how you solved this mystery!

Michael

Micheal/Derek
Well since the tacho had now been tested and proven to work, I then started to fault find the wiring!
1 Checked for 12 volt on the plug of the tacho
2 Made sure all the earths were ok on the plug as well.
3 lucky last checked for negative pulse from the distributor....was open circuit.
So I ran another lead back from the coil to the back of the tacho and it came to life!
There was so many old wires next to the coil I just ran a new cable!
Problem solved.
Dennis

Dennis,

Doesn't sound like it was too hard to track down once you verified the tach.

Michael

Dennis,

glad she's fixed, WAHOOOOOOOOOOOOOO!!!!!!!

your mate on the DTBB, George