Hood Tach wiring

I have a factory hood tach on my 70 GS, but it has been disconnected for quite a while. The previous owner looks like he tried to splice some wires to get it to work.

Does anyone know how it's "supposed" to be hooked into the wiring harness?

It has a black and brown wire and the wires for the lights. I don't care about the lights for now, I just need to make sure if the tach is working or not. I ran the brown wire from the tach to a brown wire that is at the driver's side end of the harness, where it had been spliced, and the black to ground and didn't get anything on the tach. I thought that the tach was supposed to be connected somewhere along the line, to the coil, but it's been a very long time since I've work on an older car, and am having to relearn a lot.

Thanks,
Scott

 

If I recall correctly, the brown wire is the coil lead. I can look in my manual tonight if this question isn't ansered sooner.

 

Thanks, I thought it had something to do with the coil.

I've seen where a lot of people have the service manuals, where do they have those at? I've got the assembly manual that the factory used, but I scoured ebay the other night looking for a service manual and all I could find was for the full sized Buicks.

I also went to the Haynes site and they don;t have anyhting listed for the 1970 mid sized either.

 

Yep

Brown goes to the neg side of the coil. I believe the black is the ground. If not then the grey wire is the ground. The way you can tell is, there are two lights in the tach, and four wires coming out. You should be able to figure it out.

That being said, I'm (sadly) certain the tach will not work. Having gone thru this very problem last year. It is also hard to get answers here, because many are not that experienced with electronics. Oh, and don't try it at home. Too much heat will damage the components!:Smarty:

Corrosion and broken connections are the typical problems (and I'm talking about cracks in the solder that cannot be seen with the naked eye, and the proper equipment needed is NOT in your home.

I am an Electrical Engineer, and I didn't have the proper tools. Fortunately, my neighbor is also, and he took it into work where he did. Then he brought some old equipment home and we tested mine. I can ask him if he wants to look at yours, now that we finally figured out exactly how to do it without putting it on a running car.

I'd expect he'd charge less than $100, unless it needs components...There is a place in Ill that does them too, their prices start at $170 and up to $500 or so depending on the problems... I think they also (for $75) dissemble and give an estimate, can't recall for sure...