Daytime Running Light Relay Circuit Description

Power is supplied to the DIMMER and DRL No. 4 relays when the HEAD relay is turned on.

The HEAD relay turns on by turning the light control switch to the TAIL or HEAD position.

The DIMMER relay turns on by turning the headlight dimmer switch to the LOW, HIGH, or FLASH position.

The main body ECU determines the light control switch position and turns on the DRL No. 4 and DIMMER relays.

The DRL No. 4 relay and the daytime running light resistor are parallel circuits. If the light control switch is OFF, electric current flows to body ground via the resistor instead of driving the DRL No. 4 relay. The headlights come on and dim according to the amount of resistance.

Was this article helpful?

0 0
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


  • cairn
    What does the dimmer relay control on toyota sequoia?
    4 years ago

Post a comment