I have a 1983 240 DL sedan (auto). It has a clock on the instrument panel which is broken, and I have a tachometer for the same model car which I would like to put in the clock's place. I have heard that the electrical connections for a tach exist in my car, but I can't find them. What should I look for? The tachometer has three prongs at the top and one on the bottom. Thanks.

Thanks everyone! I was getting confused because the wire from my coil is solid grey, and it took me a while to realize that it was the one I was looking for. The tach works perfectly now, though. Yay!

When you remove the gauge cluster to install the tach. Look around behind it for a white/red wire. This will usually have a plastic cover over the terminal. This
connects to the single wire connector on the back of the tach. It's marked '1'.
The other three connectors are for the wiring harness for the small clock that
can be installed just to the right of the cluster. There aren't any other connections for the tach. It gets power and ground from the pin connections when
you screw it down to the cluster. You may want to get the blanking plug that
fills the spot where the clock adjuster knob comes through. At least plug the
hole so you don't get dust and dirt inside the cluster.

Dave 82 242ti 278k mi.

In the area behind the speedo there should be a off-white or gray wire with a red stripe, it also has a connector on the end. It should attach to the bottom prong. Good luck!
--
Bruce S. near D.C.