I abandoned the idea of connecting this timer (Intermatic) to a 3 way switch. I was hoping to change the wiring to a two-way switch set up, but this didn't work for me. I thought I could disconnect wires from one of the two switches to accomplish this.
Let me explain what I did. For one switch I have two black and one white wire, when I checked the three with a non contact tester, one black wire was hot. I connected timer switch to these wires, but the switch didn't work and didn't turn on. The other switch for the same lights had a black, red, and white wire.
All three set off the non contact tester (super confusing for me). Two other white wires in the box were tied off together. I thought these were neutral, but they also set off the tester. When I checked the three hot wires (red white and black wires described above), they had different voltages one was 2 or so, the other was 7, and the third was 17 or so.
Just curious what this all means. I tried connecting the timer switch to the black red and white wires, and this too did not work.
Old post below........
Trying to connect a timer switch to a 3 way switch (intermaric ej600).
Timer switch has four wires, red white blue white and black.
Old switch has three wires, two black and white.
There is a bundle of white wires in the box not being used
Not enough wires to connect to the red and blue wires on timer switch.
I tried to follow the instructions to no avail. I connected the black wire connected to the old switch (black screw) to the black wire on the timer switch. The white wire from the old switch I connected to the white wire from the new switch. The blue wire I connected to the other black wire from the old switch. The red wire I connected to a red wire that was previously bundled to two black wires in the box. This caused the lights to flicker at about one hertz.
The instructions said to connect the remaining two wires from the old switch to the red and blue wires. That would have meant connecting the white neutral from the old switch to either the red or blue wire from the new timer switch. I didn't know what to connect the white wire from the timer switch.