car has had recurring problem with battery dead after a few days of
inactivity.  battery & charging system test fine but lexus dealer
states the trouble can be traced to "one of the back doors" and to fix
it they suggest replacing the ECM for the alarm/security system at a
cost of $498.  i asked several questions:

1) if one of the back doors had a problem can a switch or sensor be
replaced.  answer: no, the ecm must be replaced.  part #8793033123
costs 318.80 and 2 hrs labor to install ecm and then re diagnose.
then service writer tells me "this may not cure the problem if
something shows when we re diagnose".  so could be 500 plus much more,
they will not say or commit to a figure.

2) I asked about just disconnecting the ecm (they insist the security
has it's own) and locking the  car with the key.  when asked where the
ecm was located they told me "maybe in the trunk".

I cannot see the value to spending 500 on the car (maybe lots more)
but would like to stop the battery drain.  i need to get a service
manual but in the meantime, does anyone know where the security ecm is
located and if it can be unplugged?  also, if it is unplugged do i
lose keyless entry and trunk opener?  any comments or recommendations
appreciated.  i hate the lexus dealer...love the car.  thanks
G