I got a junkyard stock tach for my truck ('85 F150 5.0L V8), it didn't come with one stock. There was a blank space in the cluster just asking to be filled.

Since my truck didn't come with a tach, the printed circut film on the back of the cluster doesn't have tach connections.

The back of the tach has 4 posts marked "C", "G", "B" and "8". I have wiring for a Sun tach that died about 2 years ago. It has red, white, black and green wires. Red is 12v, green to coil, black to ground and white to the dash lights.

I connected the green to the "C" post, the black to the "G" post, the red to the "B" post, and nothing to the "8" post. The tach seems to work, but I think it may be reading high. I have no way to confirm the reading as the old tach is dead.

I can supply the part # off the front of the tach if that is any help.

85 F150 4x4, Bal & BP 302, EFI, K&N air filter, Heddman headers, High-flow Cats, Custom side-exit exhaust, 4" Rancho lift, Rancho 9000 shocks, Rancho Torque Arms, 4.10:1 gears, Rear limited slip diff., 33" BFGs, Warn Winch, SnugTop.

 

Which one is running to the coil > - terminal?

Dennis

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[updated:LAST EDITED ON 21-Nov-02 AT 11:04 PM (EST)]>Which one is running to the coil > - terminal?

The green wire goes from the coil to the "C" terminal on the tach. Ground (black wire) goes to the "G" terminal of the tach, and the 12v (red wire) goes to the "B" terminal of the tach. Nothing goes to the "8" terminal of the tach.

I guess I'm concerned about two things:
1: Do I have it wired correctly? I just guessed at the conections. the "C" and "G" connections seemed to be fairly logical. the "B" and "8" terminals confused me. Why does a tach need 4 terminals?
2: Do I have a tach for an 8 or a 6 cylinder engine (is there even a difference)?

85 F150 4x4, Bal & BP 302, EFI, K&N air filter, Heddman headers, High-flow Cats, Custom side-exit exhaust, 4" Rancho lift, Rancho 9000 shocks, Rancho Torque Arms, 4.10:1 gears, Rear limited slip diff., 33" BFGs, Warn Winch, SnugTop.

 

4 wires

1)Power
2)Ground
3)Tach
4)Bulb for lighting



Black: ground
Red: hot ("key on" fuse panel)
Green: "tach" (HEI) or coil
White: Headlight dimmer switch (for your face light)
--------------------------------------------------------------------------------


Dennis

F.T.E. Assistant Administrator
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[updated:LAST EDITED ON 22-Nov-02 AT 10:01 AM (EST)]Dennis,

I think you are missing my point, or, I didn't make it clear enough.

I'm trying to put a stock Ford tach from an F150 into my F150 that didn't come with one. The Ford tach fits right into the instrument cluster in place of the blank in my cluster. I had wired in an aftermarket Sun Pro tach (mounted on the column) that is now dead. I'm trying to figure out how to use the wires from the Sun tach to run the Ford tach.

>4 wires
>1)Power
>2)Ground
>3)Tach
>4)Bulb for lighting
>Black: ground
>Red: hot ("key on" fuse panel)
>Green: "tach" (HEI) or coil
>White: Headlight dimmer switch (for your face light)

That part I understand. The Ford tach, since it is part of the instrument cluster does not have a light, aso I don't think I need to use the white wire.

The thing I need to know is which of my existing wires (from the Sun Tach), go to which terminals of the Ford tach? The terminals are marked; "C", "B", "G" and "8". I have a coil wire, a ground wire and a 12V wire.

85 F150 4x4, Bal & BP 302, EFI, K&N air filter, Heddman headers, High-flow Cats, Custom side-exit exhaust, 4" Rancho lift, Rancho 9000 shocks, Rancho Torque Arms, 4.10:1 gears, Rear limited slip diff., 33" BFGs, Warn Winch, SnugTop.

 

No. It was me that mis-read it

On thre cluster there are two main wire connections for the tach

Spot #11 Dark Green/Yellow
Spot #12 Black /Light Green

#11 runs to the igition module then to the coil.


#12 runs downs to a wire with a 8-9 Ohm resitor to the ignition switch




Dennis

F.T.E. Assistant Administrator
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Thanks to all who tried to help.

Got the printed circut off the tach-donor cluster.