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Car Alarm

I have a 2000 Lexus RX300. The rear passenger side door randomly does not close when I click on the alarm. When this happens, the alarm does not turn on and then the rest of the alarm system starts acting up until I manually close all the doors and then turn on the alarm. After I do this, the alarm works well. My dad and I opened the door that I am always having trouble with to see if anything was loose, but it all seemed ok. We are, however, not experts. Does anyone know if the problem is with the door or the alarm? I greatly appreciate any suggestions on this issue because I am stumped.

Not familiar with the 2000 Lexus. However, I suspect this is door wires getting frayed and starting to break after 13 years of flexing.

Get yourself a Hanes or Chiltons or possibly a FACTORY manual; which will have diagnostics in it. Run through the flow chart. However, you state that after you get the door closed; it all works fine. Most alarms don’t arm correctly when a door is open or the key is still in the ignition.

I suspect that if you peel back the rubber boot covering the door wiring; you will find some chaffed or broken insulation or wiring that is cracking. Go back around 6 inches on each side since you don’t wish to make repairs in wire that is stiff from flexing. And replace/repair the door wiring harness as needed. This will probably fix your problem; although this is just my guess.

Good luck.