I've seen a few posts in the past asking about the factory tach being added to a truck that wasn't originally equipped with it.
I've also seen posts about the 80 dash circuit being a bit different from other years.
This leads me to ask, exactly what is needed to add a factory tach to my current cluster? I have an 80 with the guage cluster, no tach. I have access to a couple newer (82 & 85) clusters that have the tach. Both were V8's, I have a 6.
What do I need to do, beyond installing the tach in my cluster, to make it work?

 

I don't have the book in front of me right now so specific moves will be hard to give, but the short answer is if you have an 80 equiped with gauges, you would just need to re-pin some of the wires at the connection that plugs into the cluster. If your truck has idiot lights, you'll need to change the connector to the larger guage-type connector, which essentially means repinning the whole thing. You also need to change the idiot light oil and temp sensors to the guage-type sensors.

 

Re-Pinning is a last resort.Technically,us 80 guys should be finding a tach cluster from a truck built before July 80,since the printed circuit is different(easy way to tell is green for 1980 vs red for 81-86).Any tach from 80-86 will work,only the printed circuit is different.So,try and find an 80 tach printed circuit.If you have Ammeter and Oil pressure gauges,get a tach from another Ammeter/Oil Pressure gauge truck.If you have idiot lights for the Ammeter and Oil pressure,try and get a cluster from another Idiot light truck.You'll only have to re-pin if you use an Ammeter/Oil pressure gauge cluster in Idiot light truck,and vice versa.

However,I have an 82 tach cluster in my 80,and the only differences I have found is in the top indicator lights.The Brake warning light is the Right turn indicator,and the right turn indicator is my Brake warning light.I simply pulled the instrument bezel,gently pulled off the Brake and Right Arrow indicator,swapped em around,and glued them back on.Easy fix.I can't guarantee it's the same for all the printed circuits,but ya don't know til ya try.

The swap is plug and play,nothing has to be done except collecting the right parts and being careful not to destroy the wiring connector and speedometer cable when you remove them.Good luck.

 

As stated, it's an 80 with guages.
I was planning to just add the tach to my cluster, rather than swapping the complete cluster.

 

In that case,I think it's just a matter of removing the filler plate,putting in the tach,and swapping out the printed circuits.Don't quote me as i've never tried it,but I think the backings are all the same.

 

So the printed circuit is different between tach/no tach dash clusters? Seems a bit excessive. I figured the tach curcuit was already there, just not in use.....
Also, wondered what was involved with making it read correctly for a I6 vs V8.

 

Yep,but the only difference is that the tach printed circuit has the extra circuit for the tach,the non-tach circuit doesn't have it.

Here's my old printed circuit,if you look,you can see where there's no printed circuit going up and over where the tach goes.On Tach Printed Circuits,this is there.I didn't get a pic of my tach circuit,so I don't have anything else for you to compare too,but maybe someone else can chime in with a pic.




Also,as far as my understanding goes,the I6 and V8 trucks both get the tach reading from the coil,so there's no difference.The Diesel tachs read from somewhere else.

 

I've never any difference going from the 8 to the 6. My recommedation on repinning, which in your case would be only a couple of wires, is based on that you already have a line on the 82-85 clusters. The 30 seconds it will take you to re-pin will be far less time that it will take to find an 80 tach cluster. The non-cluster printed circuit is different, so you will need to change that if you add the tach to your existing cluster. You'll have to change that wheter you use an 80, or a newer, cluster.

 

Oh, yes.....

No... Keep searching and find pics, or maybe somebody can repost pics, but the two are
entirely different.

I believe this involves only on which of the 4 pins you connect the coil wire but I could be
wrong, somebody will correct me if I am.....

 

As they say, learn something new all the time....
If the curcuit doesn't exist, would it be possible to just wire the tach using regular wire, rather than changing the printed curcuit? It looks like the tach mounts like the rest of the gauges, using the nut as not only the mount, but also for wiring connections.

If the 82-85 cluster can be used with just a minor re-pinning at the connector, I might go that route. Just need a pic showing the wires to move.

Was also gonna snag the intermittant wiper switch/governor while I was in there...... Any issues using those in the 80?

 

On the back of the tachometer, there are two grounds. One is marked with an "8" and the other is a "G". The V8 application makes use of both grounds. The 6 cylinder does not use the "8" ground. All of this is handled by the original wiring. [I believe I am correct.]

 

Um, a V8 coil fires 33% more often than a 6cyl, or the 6 cyl fires 25% less than a V8, whichever way you want to look at it.
V8 @ 2,000 RPM = 8,000 coil fires
I6 @ 2,000 RPM = 6,000 coil fires

 

Sure, I and others here have done just that.

Use the Advanced Search feature, search only in this forum, and look for terms such
as:

gauge film color
green red circuit
cluster gauges
tach installation

AND find POSTS by:

81-f-150-explorer
uncle.stosh

You might be able to find pics and other useful info in the archives.

 

I think I found the info:
https://www.ford-trucks.com/forums/3...ml#post7439524

 

Just to clarify some things.

A: 1980 is a one year wonder for instrument clusters. If you are going to do the job right you need to find another 1980 to get the correct printed circut from it, or buy a new printed circut for a 1980. There are some aftermarket ones avaliable. The gauges the tach and the speedometer itself are swappable 1980-1986, but the printed circut is 1980 only.

B: The Tach Swap will only work with trucks with ammeter and oil pressure gauges. All the wiring is already there in the cluster connector. Plug and play. If you have a truck with idiot lamps, you will have to do excessive rewiring to make it work. The entire main dash harness and engine harness is different between the two. The Ammeter Shunt is the most important difference. Without this factory shunt, full altenator charging amps (60 amps or more) will go through the ammeter gauge which is only rated at .5 amps causing fires.

C: Both Fordzilla80 and 1986F150six are correct. The tach gets it's signal from the tach test lead of the coil. So everytime the coil fires the tach gets a signal from it. It also gets power from the battery. On a V8 there are two grounds that go to the tach, on a six there is only one ground.

As you say, the firing of the coil on the V8 is more often than the I6 at the same RPMs. The extra ground on the tach error corrects the difference internally of the tach.

So to wire the tach without changing your printed circut.

1: B post on tach goes to battery power.
2: I post (or C) goes to the tach test lead of the coil
3: G is the main ground for the tach. (This has to be grounded)
4: 8 is only grounded on a V8 engine.