Operating Light Control Rheostat does not Change Light Brightness: Procedure

1. Turn the ignition switch to ON.
2. Turn the light control rheostat knob fully upwards.
3. Turn the light control rheostat knob fully downwards.
4. Turn the light control rheostat knob fully upwards and while control switch is on TAIL or HEAD.
5. Check the meter illumination.
   RESULT
   
   

   Result	Proceed to
   Meter illumination does not change when operating the light control rheostat knob.	A
   Dimmer cancel does not operate (meter illumination does not dim).	B

B → See step   3 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Combination Meter / Active Test.
5. Check the values by referring to the table below.
   COMBINATION METER:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Rheostat value	Light control rheostat/Min.: 0%, Max.: 100%	Light control rheostat switch is Dark (0%) → Bright (100%)	-

   OK

   The value displayed on the tester gradually changes according to the rheostat operation.

NG → See step   4 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Combination Meter / Data List.
5. Check the values by referring to the table below.
   COMBINATION METER:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Tail Cancel SW	Tail cancel switch is OFF/ON	OFF: Light control rheostat position is except below	-
   		ON: Turn the Light control rheostat knob fully upwards	-

   OK

   Condition displayed on the tester is the same as the actual rheostat position.

NG → See step   6 

OK → See step   8 

1. Disconnect the E1 meter and D4 rheostat connectors.
   Fig 1: Identifying E1 And D4 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   E1-4 (SW1) - D4-7 (T)	Always	Below 1 Ω
   E1-24 (SW2) - D4-3 (RV)	Always	Below 1 Ω
   E1-39 (SW3) - D4-1 (E)	Always	Below 1 Ω
   D4-1 (E) - Body ground	Always	10 kΩ or higher
   D4-3 (RV) - Body ground	Always	10 kΩ or higher
   D4-7 (T) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the light control rheostat with the connector still connected.
   Fig 2: Identifying Light Control Rheostat Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D4-1 (E) - D4-3 (RV)	Turn the light control rheostat knob fully upwards	8 kΩ or higher
   D4-1 (E) - D4-3 (RV)	Rheostat knob position is between MIN. and MAX.	The value changes gradually (Between below 1 to 8 kΩ)
   D4-1 (E) - D4-3 (RV)	Turn the light control rheostat knob fully downwards	Below 1 Ω

NG → See step   9 

OK → See step   8 

1. Disconnect the E1 meter and D4 rheostat connectors.
   Fig 3: Identifying E1 And D4 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D4-5 (TC) - E1-23 (TC)	Always	Below 1 Ω
   D4-7 (T) - E1-4 (SW1)	Always	Below 1 Ω
   D4-5 (TC) - Body ground	Always	10 kΩ or higher
   D4-7 (T) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the light control rheostat with connector still connected.
   Fig 4: Identifying Light Control Rheostat Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D4-5 (TC) - D4-7 (T)	Turn the light control rheostat knob fully downwards	Below 1 Ω
   D4-5 (TC) - D4-7 (T)	Turn the light control rheostat knob fully upwards (Tail cancel ON)	8 kΩ or higher

NG → See step   9 

OK → See step   8