You posted under EJ500 Intermatic battery-operated timer.
If you have different timer, add a comment.
I have tested EJ500 timer.
A) If this is new single-pole installation
and lights click on-off when timer turned on, then you connected red wire where blue wire should be connected.
says for single pole switch:
Timer-black-wire to Hot; Timer-blue-wire to Load (lights)
Here's how to wire timer correctly
1) Timer-green-wire connects to bare ground
2) Switch has 2 wires. Take switch wires and connect them to timer-black-wire and
timer-blue-wire. Choose either one for now.
3) Put wire nut on red wire.
Turn on electricity, and push ON-OFF button. If lights come on, timer
is wired correctly. If lights do not come on, then reverse timer-blue
and timer-black wires.
B) If you are replacing 3-way switch
, view wiring diagrams shown on link below, and then add a comment saying exact color of wires. To wire this timer for 3-way can require additional wire between switches. This is because EJ500 blue wire must always go to Load (light, fan, motor)http://waterheatertimer.org/ST01C-program.html#EJ500-wire
C) If this is older timer that stopped working, check your bulbs. Then check timer battery. Manual says if timer stops working and bulbs are good, and battery good, then reset timer and reprogram. How to reset timer. Press reset button while holding down Next/ON-OFF button.
EJ500 manual has long list of programming instructions: Add a comment if you forgot parts of programming.