2003 lexus rx 300 periodically will not start when it sits 15-20 minutes after driving. No solenoid click, no dash lights..... nothing. Jump it and it starts right up. Had the battery tested three times and
it tests out just fine. The computer shows no abnormalities. It does have an electric hoist mounted in the back for a scooter but, once again, the battery is good. Could it be the ignition? Anti-theft? The chip in the key? Might there be a short with the hoist?

 

Check engine light generally deals with emission issues and smooth running of engine.

The anti-theft (imobilizer) does not interfere with the starter ... the starter turns and turns but the engine never catches.

Based on your description it has to be one of the following .

Bad battery (some times there is crack in inside which makes it intermittent. Try honking the horn or turn on the parking light and have some one monitor them as you try to start.

Bad load (you are right as any add on would be high on my suspect list ... try disconnecting it).

Bad ignition key switch.

Bad connector battery-ign.switch -- solenoid.

Salim

 

Since it does start with a jump, I'll start with the battery and progress from there.
Thanks Salim