My 2003 RX 300 has driven great the past year. It has a fresh battery and a fresh alternator (installed about 6 months ago).

I drove it Wednesday and all was fine.

On Friday I tried starting it as usual but the engine wouldn't crank at all. No clicking no noises. The interior indicators were all on as usual, but the car did not start. I tried with two different keys in case it was a security issue. Car was indeed in Park.

I'm suspecting it may be the Starter or Starter relay at fault. Both are likely original and never changed before. IS there a way to determine or test which one of those two parts has gone bad?

Thanks
David

 

Solenoid failure is very common on these cars. It's built into the starter and easy to replace.
Rebuild kit: http://www.nationsstarteralternator....-Kits-s/37.htm

There's probably a DIY but I couldn't find it.

To rule out anything with the neutral safety switch or ignition circuit you can probably connect a remote starter switch to see if you can make the solenoid engage.

 

Thanks, is the solenoid part of the starter? I'm thinking I may replace the entire starter just to be date.

But, surprisingly, after failing to start Friday and several attempts Saturday night, I opened the hood and relay box to listen if there are any strange sounds. Somehow it started first turn and has been ok all day. Is this risky?

 

The solenoid is part of the starter. If you follow that link to the rebuild kit you will see it provides a pair of contacts and a plunger with a third contact.
These contacts wear out over time. The link has a video which explains everything.

 

I wouldn’t drive it far until you figure things out. If it does it again, lightly tape on the starter with a wrench or something, and see if it starts.