Side markers provide visibility to other drivers in low-light conditions. You should check all of your Highlander's bulbs every time you get the chance so you can replace a burned-out bulb as soon as possible. The front markers are part of the headlight assembly. The rear marker bulbs are part of the combination taillight assembly. You should be able to replace any of these bulbs in about 10 minutes.
Open the hood and locate the front side marker socket. You will see two sockets plugged into the back of the headlight assembly, towards the outside of the headlight. The turn signal bulb socket is short and fat. The marker light socket is a long, cylindrical socket, above the turn signal socket.
Rotate the socket counterclockwise to unlock it from the headlight assembly. Pull the socket out.
Pull the bulb straight out of the socket. Insert a new bulb into the socket.
Reinsert the socket into the headlight assembly and rotate it clockwise to lock it into place.
Open the back door. Remove the smooth, plastic cover on the driver's side and the small, vented cover on the passenger's side. Use a flat-head screwdriver to pry off the covers. Place a rag over the tip of the screwdriver to prevent scratches.
Rotate the bottom socket, which is the side marker/stop light, counterclockwise to remove it from the assembly.
Pull the bulb out of the socket and replace it with a new one.
Insert the socket into the assembly and rotate it clockwise. Replace the covers by snapping them back into place.
