Meter / Gauge System (For Sedan) Operating Light Control Rheostat Does Not Change Light Brightness

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE USING TECHSTREAM (RHEOSTAT)

INSPECT FUSE (GAUGE)

CHECK HARNESS AND CONNECTOR (FUSE (GAUGE) - LIGHT CONTROL RHEOSTAT)

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - LIGHT CONTROL RHEOSTAT)

INSPECT LIGHT CONTROL RHEOSTAT

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY -　LIGHT CONTROL RHEOSTAT)

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

1. Connect the Techstream to the DLC3.
   

2. Turn the ignition switch ON and turn the tester ON.
   

3. Select the item below in the Data List, and read the value displayed on the Techstream.
   
   

   Body Electrical / Combination Meter / Data List::

   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Rheostat value (A/D)	Rheostat value Min.: 0 Max.: 255	Light control rheostat switch is Dark (0)→Bright (255)	-

   OK:

   Light brightness can be changed within the specified range by actual operation.
   

1. Remove the GAUGE fuse from the main body ECU.
   

2. Measure the resistance.
   

   OK:

   Below 1 Ω
   

3. Reinstall the GAUGE fuse.
   

1. Disconnect the D29 light control rheostat connector.
   

2. Measure the voltage.
   

   Standard voltage:

   Tester Connection	Condition	Specified Condition
   D29-10 - Body ground	Ignition switch ON	11 to 14V

3. Reconnect the light control rheostat connector.
   

1. Disconnect the D29 light control rheostat connector.
   

2. Disconnect the 4P main body ECU connector.
   

3. Measure the resistance.
   

   Standard resistance:

   Tester	Condition	Specified Condition
   D29-10 (IG)- 4P-1	Always	Below 1 Ω

4. Reconnect the light control rheostat connector.
   

5. Reconnect the main body ECU connector.
   

1. Remove the light control rheostat but without disconnecting the connector.
   

2. Turn the ignition switch ON.
   

3. Using an oscilloscope, check the signal waveform of the light control rheostat.
   

   Item	Contents
   Terminal connection	D29-2 (RV) - Body ground
   Tool setting	5V / DIV, 50ms / DIV
   Vehicle condition	Ignition switch ON

   OK:

   Waveform is as shown in the illustration.
   

   HINT:

   Duty ratio changes as the illumination dims. (A becomes longer)

4. Reinstall the light control rheostat.
   

1. Disconnect the D1 combination meter assembly connector.
   

2. Disconnect the D29 light control rheostat connector.
   

3. Measure the resistance.
   

   Standard resistance:

   Tester Connection	Specified Condition
   D1-7 (ILL-) - D29-2 (RV)	Below 1 Ω

4. Reconnect the combination meter assembly.
   

5. Reconnect the light control rheostat connector.