Operating Light Control Rheostat Does Not Change Light Brightness

METER: METER / GAUGE SYSTEM: Operating Light Control Rheostat does not Change Light Brightness

Operating Light Control Rheostat does not Change Light Brightness

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK LIGHT CONTROL RHEOSTAT (OPERATION)
(a) Operate the light control rheostat and check that the luminosity of the audio system, A/C control panel and combination meter, etc., change accordingly.

Result:





B -- CHECK COMBINATION METER ASSEMBLY
A -- Continue to next step.
2. INSPECT LIGHT CONTROL RHEOSTAT




(a) Remove the light control rheostat.
(b) Measure the resistance of the light control rheostat.
Standard resistance:






NG -- REPLACE LIGHT CONTROL RHEOSTAT
OK -- Continue to next step.
3. CHECK WIRE HARNESS (RHEOSTAT - ECU)




(a) Disconnect the D5 ECU connector.
(b) Disconnect the R5 rheostat connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE DRIVER SIDE JUNCTION BLOCK
4. CHECK COMBINATION METER ASSEMBLY




(a) Disconnect the C8 meter connector.
(b) Using an oscilloscope, check the signal waveform of the combination meter.






OK:
Waveform is as shown in the illumination.
OK -- REPLACE COMBINATION METER ASSEMBLY
NG -- Continue to next step.
5. CHECK WIRE HARNESS (METER - ECU)




(a) Disconnect the C8 meter connector.
(b) Disconnect the D5 ECU connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- REPLACE DRIVER SIDE JUNCTION BLOCK