Vehicle Exterior

Taillight Relay Circuit

~1min read
DESCRIPTION

The main body ECU receives headlight dimmer switch information signals, and illuminates the clearance lights, taillights and license plate lights.

WIRING DIAGRAM
CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses and bulbs for circuits related to this system before performing the following inspection procedure.

PROCEDURE
  1. PERFORM ACTIVE TEST USING TECHSTREAM (TAILLIGHT RELAY)

(a) Using the Techstream, perform the Active Test (See page ).


Main Body

Tester Display

Test Part

Control Range

Diagnostic Note

Taillight Relay

Taillight relay

ON/OFF

-

OK:

Taillight relay operates (taillights illuminate).


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG
  1. CHECK HARNESS AND CONNECTOR (BATTERY - MAIN BODY ECU)

(a) Remove the main body ECU (See page ).

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

A-14 (TRLY) - Body ground

Always

11 to 14 V

Text in Illustration

*a

Front view of wire harness connector

(to Main Body ECU)


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

Test yourself

A quick Toyota 4Runner quiz: every answer comes with an explanation and a link to the manual page.