2001 TOYOTA COROLLA 1.8 LE RT HEADLIGHT IS NOT TURNING ON BUT THE LT IS WORKING FINE. BOTH LIGHT BULB ARE GOOD. CHECK THE VOLTAGE ON SOCKET AND BOTH WIRES (SPLICES) ON RT SIDE, FOUND 0 VOLT. DO YOU HAVE ANY DIAGRAM TO FIND THE FUSE OR RELAY THAT CAN CAUSE THIS PROBLEM.

Check brake light switch, probably under dash,
on or next to brake pedal lever.
If bulbs and switch[es] check out, have helper press pedal,
and check for voltage/power at sockets.

Chances are you have a short or a bad ground in the circuit.
I would check for voltage and ground at the sockets for that side.
The parking light voltage is grounding thru the turn signal side thru the indicator lamp on the dash.

Daytime Running Lights (DRL) feature only activates the front low beam headlights. The rear parking light are not turned on by the DRL, they only come on in dark conditions or by selecting the light manually.

HEAD LIGHT BULB COULD BE BLOWED.REPLACE HEADLIGHT BULB STILL DONT WORK USE A 12 VOLT TESTLIGHT CHECK TO SEE IF HEADLIGHT BULB SOCKET GETTING POWER WITH LIGHT SWITCH ON POSITION HOOK TEST LIGHT WIRE TO A GOOD GROUND THEN PROBE POSITIVE SIDE OF HEADLIGHT BULB SOCKET.IF TEST LIGHT COME ON THEN MORE LIKELY BULB SOCKET WORN OUT NOT GETTING GOOD GROUND CONTACT INSIDE SOCKET OR GROUND WIRE LOOSE BROKEN.

The contacts in the headlight relay have probably burned. Try swapping the relay with an adjacent one to see if that fixes the problem

How to Change Headlights in a Toyota Corolla. :--- the procedure is as follows:-------- 1)Unfasten the battery cables on the Toyota Corolla with an open end wrench and remove the battery from the engine compartment. Set the cables aside so that they do not come into contact with each other or any metal parts. 2)Remove the coolant and water containers that are in the engine compartment near the front of the motor by undoing the brackets that are holding them in place with a socket wrench and moving the containers aside. They only need to be moved enough to provide you access to the area behind the headlamps and do not need to be drained.3)Locate the headlight plug on the back of the headlight and turn the plug 1/4 turn counter-clockwise to loosen the plug. Then pull it straight back to detach it from the headlight.4)Locate the clip on the side of the plug and push it in and up to detach the old headlight bulb. Take the old bulb out of the plug and place the new bulb in the plug using a clean cloth to handle the bulb.5)Push the new bulb in to the plug and turn it until you hear the clip lock into place. Insert the plug into the back of the head light assembly and turn it 1/4 turn clockwise to secure the plug. 6)Repeat this procedure with the other headlight bulb and then move the coolant and water containers into place and secure then to the vehicle. Put the Toyota Corolla battery back in the engine compartment and reattach the battery cables. Thats it. This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya

Power flows from the battery to the main fuse. Then it flows to the control coil and contact side of the headlight relay. When you turn on the headlights, the headlight switch provides ground to the control coil in the headlight relay and that operates the contacts. The contacts allow power to flow to the right and left hand headlight fuses. Power flows to the headlights. The headlight switch is what provides ground to the high and low beams on the headlights.

To diagnose, remove the headlight relay. Using a voltmeter, check for battery voltage on terminals 3 & 4 in the socket with the key in the RUN position. Then turn on the low beams. Test for good ground on terminal 1 in the socket. If you're not getting ground, then you've got a problem with either a bad headlight combo switch or a bad ground. If you get good ground on terminal 1, reinstall the relay, turn on the low beams and test for power in the headlight sockets. If you get battery voltage, that confirms you've got good fuses and wiring up to that point. Next, check for good low beam ground on the red/green wire in the bulb socket. If you're not getting good ground, it's either a bad combo switch or bad ground from the combo switch. Then turn on the high beams and check for good ground on the red/yellow wire in the bulb sockets.

It wouldn't hurt to clean the ID ground on the left side of the instrument panel, but based on everything you've said so far, this sounds like a bad combo switch

Either a bad bulb or a bad socket.... bulb not in right. Wiring problem. Not the brake switch.

Could be a bad relay switch contact. Or bulb contacts. Remove the bulbs and check it with a 12V test light. Aligator clip to any ground and touch the contacts inside the bulb socket.

remove the cover on the back of the head light and twist the plastic holder counter clockwise a quarter turn take the old bulb out and dont touch the glass on the new bulb while reinstalling it good luck please rate -jeff