Operating Light Control Rheostat does not Change Light Brightness [08/2019 - ]: Procedure

1. Operate the Techstream according to the display and select the Data List.

   Refer to DATA LIST / ACTIVE TEST [08/2019 - 08/2021] , or refer to DATA LIST / ACTIVE TEST [08/2021 - ]

   COMBINATION METER
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Tail Cancel SW	TAIL cancel switch condition/ON or OFF	ON: TAIL cancel switch on OFF: TAIL cancel switch off	-
   Rheostat value	Light control rheostat switch input/Min.: 0, Max.: 100	Light control rheostat switch fully turned downward (0) → fully turned upward (100)	Unit: %

   OK

   Light brightness can be changed within specified range by manual operation.

Result: 

OK 

REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL [08/2015 - 08/2022]  , or refer to  REMOVAL [08/2022 - ] 

Result: 

NG 

See step  2

1. Inspect the light control rheostat.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   1. Remove the light control rheostat.

      Refer to REMOVAL [08/2015 - ]

   2. Measure the resistance according to the table below.

      Standard Resistance

      Tester Connection	Switch Condition	Specified Condition
      7 (T) - 5 (TC)	TAIL cancel switch off → on	1 MΩ or higher → Below 1 Ω
      7 (T) - 1 (E)	Always	8 to 12 kΩ
      3 (RV) - 1 (E)	Light control rheostat fully turned upward → fully turned downward	8 to 12 kΩ → Below 50 Ω

Result: 

NG 

REPLACE LIGHT CONTROL RHEOSTAT. Refer to  REMOVAL [08/2015 - ] 

Result: 

OK 

See step  3

1. Disconnect the F14 combination meter assembly connector.
2. Disconnect the F5 light control rheostat connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F14-35 (TC) - F5-5 (TC)	Always	Below 1 Ω
   F14-33 (RHIG) - F5-7 (T)
   F14-34 (TR) - F5-3 (RV)
   F14-1 (E2) - F5-1 (E)

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Replace the combination meter assembly with a new or normally functioning one. Perform an operation inspection.

   OK

   Combination meter assembly operates normally.

Result: 

OK 

END 

Result: 

NG 

GO TO LIGHTING SYSTEM. Refer to  PRECAUTION [08/2019 - ]