Headlight Control Relay Circuit
WARNING: This page is about a different car, the 2000 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Verify normal headlight operation before performing this test.
- Turn ignition off. Disconnect anti-theft ECU connectors T3 and T4. Turn ignition on. Using a voltmeter, measure voltage between ECU 12-pin connector T3 terminal No. 10 (Red/Black wire) and body ground. See Figure. See WIRING DIAGRAMS . If voltage is 10-14 volts, go to next step. If voltage is not 10-14 volts, repair or replace wire harness and connectors between headlight control relay and anti-theft ECU.
- Check anti-theft ECU pin voltages. See ANTI-THEFT ECU PIN VOLTAGE TESTS under COMPONENT TESTS. Replace components as necessary and retest system operation.