Operating Light Control Rheostat Does Not Change Light Brightness: Procedure

1. Operate the rheostat and check that the quantity of light for the combination meter assembly, audio system and A/C control panel etc. are normally changed.

   Result

   Result	Proceed to
   Combination meter does not change.	A
   All light do not change.	B

B → See step   5 

A: Go to next step 

1. Check the date list of body ECU.

OK → NORMAL 

NG: Go to next step 

1. Measure the voltage according to the value(s) in the table below.
   Fig 1: Identifying Light Control Rheostat Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connector	Condition	Specified condition
   1 (T) - Body ground	Ignition switch ON, Taillight switch OFF → ON	Below 1V → 10 to 14V
   2 (IG) - Body ground	Ignition switch OFF → ON	Below 1V → 10 to 14V

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

   Standard resistance

   Tester Connector	Condition	Specified condition
   5 (E) - Body ground	Always	Below 1Ω

NG → REPLACE LIGHT CONTROL RHEOSTAT 

OK: Go to next step 

1. Check the resistance between terminals 8 (TC) of light control rheostat and B5-18 of body ECU connector.

   Standard resistance

   Below 1Ω

2. Check the resistance between terminals C9-16 of combination meter assembly and B5-5 of body ECU.

   Standard resistance

   Below 1Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE COMBINATION METER ASSEMBLY 

1. Measure the voltage according to the value(s) in the table below.
   Fig 2: Identifying Light Control Rheostat Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard voltage

   Tester Connector	Condition	Specified condition
   1 (T) - Body ground	Ignition switch ON, Taillight switch OFF → ON	Below 1V → 10 to 14V
   2 (IG) - Body ground	Ignition switch OFF → ON	Below 1V → 10 to 14V

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

   Standard resistance

   Tester Connector	Condition	Specified condition
   5 (E) - Body ground	Always	Below 1Ω

NG → REPLACE LIGHT CONTROL RHEOSTAT 

OK: Go to next step 

1. Check the resistance between 1 (T) of light control rheostat and R12-21 of instrument panel junction block assembly.
   Fig 3: Identifying Light Control Rheostat & Instrument Panel Junction Block Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard resistance

   Below 1Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Measure voltage between terminal R12-21 of instrument panel junction block assembly and body ground.

   Standard voltage

   Combination switch	Specified condition
   OFF	Below 1 V
   TAIL	10 to 14 V

NG → REPAIR OR REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY 

OK → REPLACE COMBINATION METER ASSEMBLY