Release the roof from the coach body carefully.
Cut the light bar according to the length of coach in unit. The white line in the figure is the separation line of unit.
Put the modified light bar into the coach for double-checking its length.
One 470uF/25V is required to prevent LED from blanking due to possible unstable power suppling.
Solder the capacitor on the light bar as figure.
Double-sided tape can be used for fastening the light bar.
Connect the IN1/IN2 of light bar to the contact.
Turn around the light bar to let LED face inside the coach.
Put the roof back.
Install the coach on the track for testing the fantastic light bar effect.