Operating Light Control Rheostat does not Change Light Brightness: Procedure

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 / Date List.
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%)	-
   Tail Cancel SW	Tail cancel switch is OFF/ ON	OFF: Turn the light control rheostat knob is not fully downwards	-
   		ON: Turn the light control rheostat knob fully upwards	-

   OK

   The value displayed on the tester gradually changes as the actual rheostat operation.

NG → REPLACE COMBINATION METER ASSEMBLY 

OK: Go to next step 

Fig 1: Light Control Rheostat Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Inspect the light control rheostat.
   1. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      Tester Connection	Switch Condition	Specified Condition
      7 (T) - 1 (E)	Always	10 +/- 2 kΩ
      3 (RV) - 1 (E)	Knob turned fully upward	10 +/- 2 kΩ
      3 (RV) - 1 (E)	Knob turned fully downward	Below 50 Ω
      3 (RV) - 1 (E)	Knob turned from fully upward to fully downward	10 +/- 2 kΩ → Below 50 Ω

2. Inspect the TAIL cancel switch.

   HINT: 

   The TAIL cancel switch is built into the light control rheostat.

   1. Measure the resistance of the rheostat.

      Standard resistance 

      Tester Connection	Rheostat Position	Specified Condition
      7 (T) - 5 (TC)	Knob turned fully upward (TAIL cancel condition)	10 kΩ or higher
      7 (T) - 5 (TC)	Knob not turned fully upward	Below 50 Ω

NG → REPLACE LIGHT CONTROL RHEOSTAT 

OK: Go to next step 

1. Disconnect the E19 meter connector.
   Fig 2: Identifying Combination Meter - Light Control Rheostat Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the E2 rheostat connector.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   Tester Connection	Condition	Specified Condition
   E19-26 (SW1) - E2-7 (T)	Always	Below 1 Ω
   E19-27 (SW2) - E2-3 (RV)	Always	Below 1 Ω
   E19-30 (TC) - E2-5 (TC)	Always	Below 1 Ω
   E19-34 (SW3) - E2-1 (E)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

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

   OK

   Combination meter assembly operates normally.

NG → GO TO LIGHTING SYSTEM 

OK → END (COMBINATION METER IS DEFECTIVE)