'72 Idiot to Tach Swap

[aweedman]

I have a '72 Mustang with idiot lights. I'd like to swap out to a tachometer. I found a good article on doing the swap:

http://www.mustangsandmore.com/ubb/RichPajzerGauges.html

However, trying to find the wire connector that plugs into the tach is going to be real tough. Can I cut the connector off and just solder directly to the wires?

 

[2+2GT]

I have a '72 Mustang with idiot lights. I'd like to swap out to a tachometer. I found a good article on doing the swap:

http://www.mustangsandmore.com/ubb/RichPajzerGauges.html

However, trying to find the wire connector that plugs into the tach is going to be real tough. Can I cut the connector off and just solder directly to the wires?

No, the connector problem you'll have is the plastic one connecting the dash cluster to the harness. It's different from the standard one, and of course the plug connects to a circuit board, not wires. The tach plug is easy.

I would not, as the site directs, cut and solder the wires. IIRC, they use the same connector on the wire, it should be a simple matter to disconnect them from the pin block and insert them into the proper block.

You could search until you found someone selling the cluster who was smart enough the remove the harness with it. Or you could buy a new harness.

 

[BarnStang]

Here is a write up I had in my docs library that may work for you as well.

 

[aweedman]

Thanks

That is an awesome write up! There is a wiring harness on Ebay right now but it's $425 which seems pricey since all I really care about is the one plug. Does anyone have a lead on a cheaper option? Do you know anyone that has actually cut the 18 pin and made it work?

 

[Gud T.B. Blown]

Finding the correct connector plug for a tach cluster is not as easy as you might think. It is easier to find a working tach and just intall it in your existing cluster. It will bolt right in and then just hardwire it in. IIRC it's one wire to the coil and one to the ignition and you're set. The printed circuit will fit but not exactly so only half of the lights will work.
I know this works because this is what I did while waiting to find a reasonably priced tach cluster and wiring harness. Also, you don't need to buy the underhood tach wiring harness. I only used the in car wiring harness and everything, tach included, worked perfectly.

 

[aweedman]

Good point pushrod. I'm wondering if you just get the tach by itself and also get a new circuit board for the tach if that would work?

 

[Gud T.B. Blown]

The tach printed circuit will not fit because the connector plug for the tach harness is smaller than the connector plug for the non-tach cluster. Save your money and use the printed circuit you already have.
And when I said half the lights will work I meant on the tach. The speedo and gas gauge lights are unaffected and, again, IIRC 2-3 of the lights for the tach will match up but it's still enough to see at night.

 

[miffy68]

1972 mustang Tacho

Hi I am in Australia and have a 72 mach1 with Tacho, my problem is that when the car is started the tacho sits around 800 rpm but when I rev it jumps all over the place. I have a spare tacho and it does the same. I have had the loom out and done some repairs and I have got voltage on one of the pins of the tacho 2 pin plug. I have traced the other end down to the fuse box and all looks good. I have had a look at the wiring diagram and am not sure how it receives the signal from the coil, the diagram says it goes to the carby idle solenoid after the fuse box. I assume the tacho gets its power from the ignition run circuit on the column. Its driving me crazy, maybe I have 2 dud tachos.

Regards

Mark

 

[72mustang]

Hi I am in Australia and have a 72 mach1 with Tacho, my problem is that when the car is started the tacho sits around 800 rpm but when I rev it jumps all over the place. I have a spare tacho and it does the same. I have had the loom out and done some repairs and I have got voltage on one of the pins of the tacho 2 pin plug. I have traced the other end down to the fuse box and all looks good. I have had a look at the wiring diagram and am not sure how it receives the signal from the coil, the diagram says it goes to the carby idle solenoid after the fuse box. I assume the tacho gets its power from the ignition run circuit on the column. Its driving me crazy, maybe I have 2 dud tachos.

Regards

Mark

Is it an after market tach because I had the same problem when I bought a cheap tach but when I put in an auto meter one it worked fine.

 

[miffy68]

Hello it is all factory instruments with factory tacho and centre gauges but when it came to Australia someone had put and Aussie falcon steering column in it, which entailed butchering the wiring loom, I have had the loom out and even found a mustang fuse box with column plugs and with the information from this thread with the instructions I have found that the resistance wire to the tach has been cut and played with, I am looking to test the resistance of this circuit and maybe install a resister and see how it works. stand by to stand by

 

[Gud T.B. Blown]

Are you using the stock ignition or an aftermarket such as MSD? If you're using an aftermarket you might need a tach adapter.

 

[miffy68]

Hello I am using a generic electronic dizzy with an electronic coil, I know the resistance wire has been cut and re joined at some stage. Maybe this could be it. I am thinking of pulling the whole loom out and tracing it for repairs.

Regards:

 

[miffy68]

Hi again, my new drama is that I ahve rewired the under dash loom vack to origional with the origional ignition plug loom, my problem is that the thick red with green stripe wire (resistance wire) attached to the ignition switch plug, I do not know what it hooks into. I have the same wire run from the tacho plug into the green junction box and it is complete, but do not know where this one hooks into, can some body please help me.

Cheers

Mark