Mystery door locks

2000 Lexus RX300 - door locks/acutators… the locks open and close perfectly with the master driver actuator lock unlock button or with the the remote IF the temp is 70 degrees or below. If the temp is above 70 degrees the the actuators for all four doors will NOT all lock…1-4 do sometimes…they vary from door to door, day to day , including the driver driver door. Actators are expensive. Because they do work when cooler it tells me they do work. Why not when warm? what do I need to do? This is my mystery… please help…

You Could Have It Scanned For Body Codes And See If Any Clues Are Revealed.


To expand a bit on common sense answer’s answer: some cars not only have an engine computer, but a body computer that runs the climate system, door locks, etc. If there is an error, there will possibly be an error code in the computer’s memory, but it won’t necessarily set a warning light. Many auto parts stores will check codes for free, but I don’t know if they will have the right scanner to get the body computer codes. Try first, but you may have to go to the dealer.

Some cars have a relay that plugs into the fuse box under the dash or under the hood…this relay takes the small signal from the lock system and turns it into strong electric signals that actually work the door locks. I can’t find a door lock relay on the parts list for your car but that doesn’t mean it doesn’t have one. That would be a fairly simple fix. Otherwise, it sounds like an electrical short circuit, loose wire, bad ground, or bad solder joint, since the behavior is temperature-dependent. But tracking it down might be a problem.

My hunch is that the power lead to the lock system has a bad connection and isn’t getting the full 12 volts to drive the solenoids when the temperature gets hotter. To see if that is the case you could run a temporary power wire to the connection on the keyless entry system that drives the solenoids and see if that changes things. If things work ok then you need to find and fix the bad connection.