No lamps working, what could it be?
Using the wiring diagram provided you can see there is a main fuse and relays involved. Check those first before moving on to checking the combination switch. The combination switch would be the most common failure component.
Combination Switch – 2001 Lexus RX300 … Details
DRL (Daytime Running Lights) Relay Testing/Inspection
Headlight wiring diagram 1 of 2 – 2001 Lexus RX300
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