Thomas- check my post of today. 3.0V on that battery may work some things for a long time (below 3.0V) but it doesn't seem to when operating the transmitter. It's not so much voltage as amperage and the transmitter seems to take more amperage to transmit the signal than the 3.0V is able to deliver. Other applications that don't call for the amperage may work just fine at 3.0V. I have quite a few of the small LED flashlights that have 9 LED's and use 3 AAA's. When I first got them, when I had used one of them quite a bit I thought I had better check the voltage because it was getting a little dim. The batteries all checked 1.0V. Because an LED takes so little juice and are primarily a short distance usable light they were actually usable at 1.0V. My suggestion is if anyone is having trouble with the remote and the locks function normally with the inside button (first things first) replace the battery and if you still have problems such as the one who started this thread does, 1st check the battery with a DVM and if it tests normal (3.3V) take it back and get another brand. I don't know about dry batteries but I have seen quite q few times over the years that a car battery will test full voltage and be so low on cranking amperage (the ability to deliver that voltage) that it creates all kind of electrical problems. Therein lies the problem with checking voltage and thinking because the voltage is good that the battery is good. I have seen over the years enough odd battery situations to write a book about. I have in my garage 2 batteries (my wife's car and my DIL's car), 1 has full voltage and 1/2 the rated CCA's and the other has 12.2V (technically almost dead) and full CCA's!

 

Have you tried the inside button and all the locks lock and unlock? Try it repeatedly at least 5 or 6 times. Do the slow down in locking and unlocking? If they do, do a search on this Lexus site (not just RX300) for lock malfunction and aftermarket replacement. A ton of information on what to do there. As one other poster said, clean the contacts. I am not suggesting this to anyone who is not knowledgeable in electronics or meticulous about what they do but I disassembled my DIL's remote and thoroughly cleaned everything. Doesn't seem like you and the other poster on this thread could have the same problem but with so many of the batteries made in China now (most good I'm sure), I am more suspect about the standard of quality than when they are made here. I have had bad Chinese made batteries of several different types (and I don't usually go for cheap batteries)

 

ok, this thread is 4 years old, hope someone could be helping on my case. for my key remote, unlock work fine, but lock doesn't. this is the case for all my 3 key remotes (2 master and 1 valet). central lock/unlock from door panel works fine.

any suggestion?
thanks,