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

DESCRIPTION

The combination meter assembly controls the combination meter illumination in accordance with the light control signals from the light control rheostat.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSE (TAIL)
(a) Remove the TAIL fuse from the main body ECU.
(b) Measure the resistance.
Standard resistance:
Below 1 Ohms
(c) Reinstall the TAIL fuse.
NG -- REPLACE FUSE
OK -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (FUSE (TAIL) - RHEOSTAT, RHEOSTAT - BODY GROUND)





(a) Disconnect the E4 light control rheostat connector.
(b) Measure the voltage and resistance.
Standard:





(c) Reconnect the light control rheostat connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
3. INSPECT LIGHT CONTROL RHEOSTAT





(a) Remove the light control rheostat but without disconnecting the connector.
(b) Turn the ignition switch ON.
(c) Using an oscilloscope, check the signal waveform of the light control rheostat.






OK:
Waveform is as shown in the illustration.
HINT: Duty ratio changes as the illumination dims. (A becomes longer)
(d) Reinstall the light control rheostat.
NG -- REPLACE LIGHT CONTROL RHEOSTAT
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY -　LIGHT CONTROL RHEOSTAT)





(a) Disconnect the E13 combination meter assembly connector.
(b) Disconnect the E4 light control rheostat connector.
(c) Measure the resistance.
Standard resistance:





(d) Reconnect the combination meter assembly connector.
(e) Reconnect the light control rheostat connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE COMBINATION METER ASSEMBLY