Dippy headlamps

I have a 2004 Lexus RX300 which has developed an intermittent fault with the HID headlights. When you switch them on they sometimes do not automatically dip, but point straight ahead as if on main beam. If you switch off the ignition and restart the car, the fault clears and the lights dip. The levelling sensor on the rear axle was replaced about eight months ago, following illumination of the dashboard warning light. In all other respects, the lights work perfectly. Nigel Sykes When the ignition is turned on, the ECU sets the headlamp beams to the optimum position. If your vehicle has AFS (air suspension system) then it is the AFS ECU which controls the headlamps.

As the headlamp control works after turning off the ignition and turning it back on, this suggests the fault may be within the ECU. I would first check the integrity of the levelling sensor connecting plug, to ensure that water has not seeped into the connection. There have also been reports of the headlamps on the RX300 being prone to condensation, causing damp within the unit. This is a less likely scenario, but worth a check. If no other fault is found, this would suggest the headlamp ECU is the most likely cause of your problem.