tmel

I have a 2000 ES300. As of yesterday every time the headlights are turned on or when you use the key FOB to unlock the door - the trunk opens. Can't find anything online about this.

Any help would be appreciated.

WILLYumD

What has been done to the car recently?

I can only think of the trunk release "wire" being exposed to the parking light "wire".

When you turn on the headlights or use the key fob, your lights turn on, sending voltage to the bulb. Maybe there's some exposed wires crossing sending voltage to the trunk as a "hey, open the trunk" signal. (Just did a Google search and some Ford/Volkswagen owners had a similar issue.)

Check your fuses? Not really sure where to start, haven't heard of this before lol.
Check your battery terminals and test your battery voltage.

Please report back this is highly intriguing lol.

LeX2K

Wires near the trunk hinge could be frayed and shorting out. Another possible cause I can think of is poor installation of a sound system or remote start.

tmel

About a week ago I replaced the headlight ballast. Used an aftermarket version. I thought that might be the cause but I disconnected it and the problem persisted.