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

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (FUSE (TAIL) - RHEOSTAT, RHEOSTAT - BODY GROUND)

(a) Disconnect the E4 light control rheostat connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Text in Illustration

(d) Reconnect the light control rheostat connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. INSPECT LIGHT CONTROL RHEOSTAT

(a) Remove the light control rheostat but without disconnecting the connector Removal.

(b) Turn the ignition switch to ON.

(c) Using an oscilloscope, check the signal waveform of the light control rheostat.

OK:

Waveform is as shown in the illustration.

Text in Illustration

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

(d) Reinstall the light control rheostat.

NG -- REPLACE LIGHT CONTROL RHEOSTAT Removal
OK -- Continue to next step.

3. 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 according to the value(s) in the table below.

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 Removal