Headlight Relay Circuit Description

HEAD relay will be "ON" by operating the light control switch. The transistor which activates the HEAD relay has two sorts: one is activated by the light control switch for fail safe and the other is activated by CPU. The one that is activated by CPU prevents the headlight from turning off at the time of trouble with the other system in the automatic operation circuit.

When the theft deterrent system is activated, it causes the transistor in the ECU to switch ON and OFF at approximately 0.25 sec. intervals. This switches the HEAD relay ON and OFF, and thus flashing the headlights (See the WIRING DIAGRAM below).

In this condition, if any of the following operations is done, the transistor in the ECU goes OFF and the HEAD control relay switches OFF, and thus stopping the headlights flashing:

a. Unlock the front LH or RH door with a key.

b. Turn the ignition switch to ACC or ON position.

c. Unlock the doors with the wireless door lock control system.

d. Wait for approximately 60 seconds.


2002 Toyota Echo Wiring Diagram
Fig. 25: Headlight Relay Circuit - Wiring Diagram Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.


When using the intelligent tester, start the inspection from step 1 and when not using the intelligent tester, start from step 2.

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