Can somebody point me to the location of the relay that controls the trunk release solenoid? When I hit the release button on the remote or in the car, I can hear a relay click under the dash somewhere. Intermittently, the solenoid will make some noise but not fully activate. The solenoid itself checks out fine, and I've ruled out a grounding issue. I suspect the relay contacts are worn and sometimes not closing properly.

 

what year is your car? 90-94 cars are prone to wiring harness failures next to the driver's side trunk hinge. constant open/close has caused some wires to become brittle and break. i would check those wires first.

 

It's a 97, and that's a good thought. I had to repair wiring at the trunk hinge on our 1997 Camry, so I understand what you are talking about. A quick look didn't show anything obviously wrong in that area on my LS, but maybe something is lurking deeper.

From studying the wiring diagram, the TR+ wire comes from the Body ECU, connector B8 pin 7, and is black in color. It goes through an intermediate connector, IF4, on pin 3. IF4 is shown as behind the driver's kick panel near the floor. From there, it goes right to the "luggage compartment door opener motor". So it would seem the problem is likely to be either the wire, a connector pin, or a bad Body ECU.

 

the trunk hinge wiring harness breakage issue was cured prior to this car being manufactured in 97 so that is extremely unlikely to be the problem

unless the car has been in an accident or else had electrical modifications (i.e. aftermarket stereo, aftermarket security system, remote start, etc.) then a wire inside the harness is almost never the problem in an LS400 (excepting the trunk harness issue on older models we just eliminated) - a connection or a relay or a bad ground or supplicant ECU as you mentioned is far more likely than a wire.