What is that....

[tex_waco_usmc]

On the back of the speedometer on an 87 there is a set of wires that go into a small green box that has a circuit board in it. I replaced the dash with a 91 Tach Dash and it doesnt have it. What is that doohickie and do I need it???

[gchemist]

It's an optical sensor for cruise control.

[Jonboy]

It also supplies the VSS signal. You need that with TBI.

[tex_waco_usmc]

So how do I use this setup in my 87 so I can have the tach? Remove all the gauges from my 87 dash and put all the gauges minus the speedo from the new dash back in and use the printed circuit from the new dash?

[Jonboy]

The tach dash is out of a 91? What does the back look like?

[tex_waco_usmc]

Originally Posted by Jonboy

The tach dash is out of a 91? What does the back look like?

I say its out of a 91 but I could be mistaken...

The back looks the same except the back of the speedometer has the nipple to plug the speedo cable in but thats it, no where to put the wires...

[tex_waco_usmc]

This is a pic of the actual dash...

[ray_mcavoy]

Originally Posted by tex_waco_usmc

So how do I use this setup in my 87 so I can have the tach? Remove all the gauges from my 87 dash and put all the gauges minus the speedo from the new dash back in and use the printed circuit from the new dash?

I think the easiest way to go would be to transfer your 87 speedometer (with it's VSS) over into that tach cluster. I believe it will involve some minor modifications to the plastic housing to make it fit. But trying to fit the tach and small fuel gauge into your non-tach cluster housing would require even more modifications.

[MalibuSSwagon]

Yes the tach dash you have is earlier, pre-electronic cruise era.

Speedometer should be an easy swap out to your current speedo. You may have to enlarge the opening for the VSS head. Since you have an 87, you need to retain the VSS for proper operation of the TBI system. Plus your mileage stays accurate.