Quick question on dash head units

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Aug 26, 2008 | 06:21 AM

quaddriver

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Cargo Master

Joined: Jan 2004

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From: Cook Forest and Irwin PA

Quick question on dash head units

I have the ability to get for free a great looking dash unit - speedo, tach and all 4 gauges for free.

My 81 has speedo and gauges and dead zone where the tach is.

Is there a switch or jumper on the tach to make this work? Its coming from an 84 F250 w/302, going into a 81 with I6

Are the tachs made for the # of cyls or settable?

thanks!

Aug 26, 2008 | 08:42 AM

subford

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From: Easton,Ks

Quote:

Originally Posted by quaddriver

Is there a switch or jumper on the tach to make this work?

Not on the tach.

Quote:

Originally Posted by quaddriver

Are the tachs made for the # of cyls or settable?

They are the same, the six or eight is selected with the wiring harness, one takes the wire to ground and the other does not (The 8 cylinder has a added wire and plug going to ground).
Pin #12 is grounded for the 8 cylinder only.
If you have a six and the wire is grounded just cut the wire going to Pin 12 or find the plug and unplug it.

Aug 26, 2008 | 09:13 AM

quaddriver

Thread Starter

Cargo Master

Joined: Jan 2004

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From: Cook Forest and Irwin PA

what are the chances that in 81 the harness has the tach wiring done correctly for the 6? I note in the 87-91 years that the harni had all options in them, they just terminate differently.

or because I had no factory tach I have no wiring at all here?

I have not looked into this at all, I just poured over the truck last night putting in my 'dibs' in the prettier pieces (has a great interior - intact seat, dash pad and door panels - in gray tho...)

Aug 26, 2008 | 09:43 AM

Franklin2

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From: Virginia

From what I gather from other posts, if your old cluster has gauges, then the wiring is there. You will have to look about the ground jumper. If the 81 truck only has idiot lights, then it's not an easy swap.

Aug 26, 2008 | 09:50 AM

subford

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From: Easton,Ks

Quote:

Originally Posted by quaddriver

what are the chances that in 81 the harness has the tach wiring done correctly for the 6?

I would say very good.

Quote:

Originally Posted by quaddriver

or because I had no factory tach I have no wiring at all here?

I bough a 1983 F150 new with no factory tach and went to a salvage yard and got a cluster with a tach and it was plug and play. No wiring changes at all.

The statement my first post above is a good one if the cluster in a 1981 is the same as the clusters in the 1983 and 1984 and are all gas trucks. This I do not know as I have no good information on the 1981.

Aug 27, 2008 | 06:26 PM

quaddriver

Thread Starter

Cargo Master

Joined: Jan 2004

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From: Cook Forest and Irwin PA

I picked up the cluster today - I find that the traces on the 'flexible PC board' for the ammeter are burned. cute. I can wire this in with a plug into the harness.

the back of the tach has 4 pins labelled 1, 8 B and G

G appears to be a ground, B appears to be +12, 1 appears to be tach and 8 appears to be that 8cyl ground - according to your diagram - so if the 81 is wired the same, bizness!

all I need to do is probe pin 12 for continuity to ground....if there....clip!

thanks!