Answer
Apr 10, 2025 - 01:34 AM
On the 2007 RX350, there actually isn’t a traditional standalone cruise control relay like you’d find in older vehicles. The cruise system is integrated into the engine control module (ECM) and works electronically with the throttle-by-wire system. So instead of a relay clicking on and off, the ECM handles cruise functions directly based on input from the steering wheel switches, brake pedal switch, and speed sensors.
If cruise isn’t working, I’d start by checking the brake light switch (common culprit), the cruise control switch itself, and making sure there are no stored trouble codes in the ECM. Fortunately, the repair manual software has a full diagnostic procedure for this, including wiring diagrams and test steps to isolate what’s going on.
