About a year ago I replaced the high beam headlamp on my 2002 Celica right side. That did not work. I checked out the old bulb and the new one via direct connect to the battery. They were both good. Left the new one in. I drove with the left high beam functioning for one year. Last month the left high beam burned out so I replaced that as well. That did work. The old bulb was definitely bad. I drove not more that 0.2 miles and noticed that BOTH high beams were working! They both have ever since. What happened? Why did the right high beam start working only after the left bulb was replaced?
Just a guess–the wiring harness may run from the left headlight to the right headlight. The connection at the left headlight may be a junction point for the wire going to the high beam on the right headlight. This connection inside the plug for the left bulb may have been intermittent and when you replaced the left bulb, you jiggled the connector enough to complete the circuit to the right headlight. If the right headlight goes out again, jiggle the socket on the left headlight.
gremlins? poltergeist? Are you positive you used the corect bulb?
Thanks. That makes sense to me. I could try asking a Toyota technician about the wiring. I remember that I checked the voltage on the right connector when I replaced the right bulb and noticed that the voltage was about 11 volts instead of 14. This should be enough to light the bulb, but if the connection from the junction were intermittent, there might not be enough current. I’ll try your suggestion if the issue comes up again.