I have a '99 RX300 with 110K miles. Over the last month, the EFI fuse has blown at random moments. I've replaced it 4 times now. The only thing in common (so far) is that it always happens when the car is idling...either in park or at a traffic light. Anybody have any idea where to look for the problem?

I checked with my ODB scanner, no DTC codes came up.

 

Welcome to CL.

Do you have any aftermarket or accessory plugged in? Please disconnect them. Electrical problems are pretty rare, unless some one has tampered with the wires. Remote starters are pretty notorious. Next are the trailer hitches. Check for salt/corrosion build up in the socket.

I would get hold of the electrical diagram for the RX and see what are the loads and you can start isolating them.

Good luck.

Salim
ps: If you have a trailer hitch, the brake circuit is energized when you are stopped. Could be coincidence or it can be a clue.

 

There's no aftermarket accessories plugged in. No remote starter, no trailer hitch. Just a stock RX300.

Another issue that might be a clue: My ODB scanner isn't showing any DTC codes, but it is showing *something* is wrong with emissions. The status light on the scanner is yellow instead of green - not very descriptive.

 

How is your idle at cold start?