LIGHTING SYSTEM > Taillight Circuit

for Preparation Click here

DESCRIPTION

1. This circuit is only for vehicles with the daytime running light system or with automatic light control system.
   

   HINT:

   1. For vehicles with the daytime running light system or with automatic light control system, the exterior lights (headlights, taillights, front fog lights and rear fog light) are controlled by the main body ECU.
      
   2. For vehicles without the daytime running light system and without automatic light control system, the exterior lights (headlights, taillights, front fog lights, and rear fog light) are not controlled by the main body ECU, so perform troubleshooting according to the Problem Symptoms Table (Click here).
      

2. The main body ECU receives the light control switch TAIL signal to control the taillight relay.
   
3. When the light control switch is in the AUTO position, the main body ECU receives the ambient light level signal from the automatic light control sensor to control the taillight relay.
   

HINT:

1. When any of the lights do not illuminate, check the bulb or wire harness that is related to the bulb.
   
2. When all of the lights that are related to the TAIL relay do not illuminate and the TAIL fuse is normal, perform the taillight relay Active Test and read the light control switch TAIL signal value in the Data List to determine if the malfunction exists on the switch side or the relay side.
   
3. The taillight relay is installed in the instrument panel junction block, so unlike conventional relays, it can not be removed for inspection.
   

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:

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

1. Connect the intelligent tester to the DLC3.
   

2. Turn the ignition switch to ON.
   

3. Turn the tester on.
   

4. Enter the following menus: Body / Main Body / Active Test.
   

5. According to the display on the tester, perform the Active Test.
   
   

   Main Body 

   Tester Display	Test Part	Control Range	Diagnostic Note
   Taillight Relay	Taillight relay	ON or OFF	-

   OK:

   Taillight relay operates. (Taillights illuminate.)
   

NG	Go to step 2

OK
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Click here)

1. Connect the intelligent tester to the DLC3.
   

2. Turn the ignition switch to ON.
   

3. Turn the tester on.
   

4. Enter the following menus: Body / Main Body / Data List.
   

5. According to the display on the tester, read the Data List.
   
   

   Main Body 

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Head Light SW (Tail)	Light control switch TAIL signal ON or OFF	ON: Light control switch in TAIL or HEAD OFF: Light control switch in neither TAIL nor HEAD	-

   OK:

   Normal conditions listed above are displayed.
   

NG	PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE (Click here)

OK

1. Disconnect the 3A instrument panel junction block connector.
   

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

   Standard Voltage:

   Tester Connection	Condition	Specified Condition
   3A-1 - Body ground	Always	11 to 14 V

   Text in Illustration 

   *1	Front view of wire harness connector (to Instrument Panel Junction Block)

3. Reconnect the instrument panel junction block connector.
   

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

1. Temporarily replace the main body ECU with a new or normally functioning one (Click here).
   

NEXT

1. Connect the intelligent tester to the DLC3.
   

2. Turn the ignition switch to ON.
   

3. Turn the tester on.
   

4. Enter the following menus: Body / Main Body / Active Test.
   

5. According to the display on the tester, perform the Active Test.
   
   

   Main Body 

   Tester Display	Test Part	Control Range	Diagnostic Note
   Taillight Relay	Taillight relay	ON or OFF	-

   OK:

   Taillight relay operates. (Taillights illuminate.)
   

NG	REPLACE INSTRUMENT PANEL JUNCTION BLOCK

OK
END (MAIN BODY ECU DEFECTIVE)