Headlight Dimmer Switch Circuit [11/2023 - ]: Procedure

1. Read the Data List according to the display on the GTS.

   Chassis > Steering Angle Sensor > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Light OFF Switch	Light control switch DRL OFF position signal	OFF or ON	OFF: Light control switch not in DRL OFF position ON: Light control switch in DRL OFF position	w/ DRL OFF Switch
   Auto Light Switch	Light control switch AUTO position signal	OFF or ON	OFF: Light control switch not in AUTO position ON: Light control switch in AUTO position	-
   Head Light Switch (Tail)	Light control switch tail position signal	OFF or ON	OFF: Light control switch in neither tail nor head position ON: Light control switch in tail or head position	-
   Head Light Switch (Head)	Light control switch head position signal	OFF or ON	OFF: Light control switch not in head position ON: Light control switch in head position	-
   High Beam Main Switch	Dimmer switch high position signal	OFF or ON	OFF: Dimmer switch not in high position ON: Dimmer switch in high position	-
   Passing Light Switch	Dimmer switch high flash position (pass) signal	OFF or ON	OFF: Dimmer switch not in high flash position ON: Dimmer switch in high flash position	-
   Front Fog Light Switch	Front fog light switch signal	OFF or ON	OFF: Front fog light switch off ON: Front fog light switch on	-

   Chassis > Steering Angle Sensor > Data List 

   Tester Display
   Light OFF Switch
   Auto Light Switch
   Head Light Switch (Tail)
   Head Light Switch (Head)
   High Beam Main Switch
   Passing Light Switch
   Front Fog Light Switch

   OK

   Normal conditions listed above are displayed.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  5

Result: 

OK 

See step  2

1. Read the Data List according to the display on the GTS.

   Body Electrical > Main Body > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Light Control Switch (HEAD)	Light control switch head position signal	OFF or ON	OFF: Light control switch not in head position ON: Light control switch in head position	-

   Body Electrical > Main Body > Data List 

   Tester Display
   Light Control Switch (HEAD)

   OK

   Normal conditions listed above are displayed.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [11/2023 - ] 

Result: 

NG 

See step  3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the steering sensor.

   Refer to REMOVAL [11/2023 - ]

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   H57-7 (HEAD) - z5-4 (H)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE STEERING SENSOR. Refer to  REMOVAL [11/2023 - ] 

Result: 

OK 

See step  4

1. Disconnect the H135 main body ECU (multiplex network body ECU) connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   H57-7 (HEAD) - H135-26 (HEAD)	Always	Below 1 Ω
   H57-7 (HEAD) or H135-26 (HEAD) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [11/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Refer to INSPECTION [12/2019 - ]

Result

Result: 

NG 

REPLACE TURN SIGNAL SWITCH. Refer to  REMOVAL [12/2019 - ] 

Result: 

OK 

See step  6

Refer to INSPECTION [12/2019 - ]

Result

Result: 

OK 

REPLACE STEERING SENSOR. Refer to  REMOVAL [11/2023 - ] 

Result: 

NG 

REPLACE STEERING WHEEL SWITCH HOUSING. Refer to  REMOVAL [11/2023 - ]