Inspection Procedure

WARNING: This page is about a different car, the 2008 Toyota Yaris. However, it is still accessible from the selected car via links, so may be relevant.

READ VALUE OF TECHSTREAM (RHEOSTAT)

Connect the Techstream to the DLC3.
Turn the ignition switch ON and turn the tester ON.

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

Body Electrical / Combination Meter / Data List:

BODY ELECTRICAL / COMBINATION METER / DATA LIST

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Rheostat Value (A/D)	Light control rheostat switch / Min.: 0, Max.: 255	Light brightness changes within specified range: Dark (0) to bright (255)	-

OK:

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

NG: Go to step 2

OK: REPLACE COMBINATION METER ASSEMBLY

INSPECT FUSE (GAUGE)
1. Remove the GAUGE fuse from the main body ECU.
2. Measure the resistance.
  OK:
  
  Below 1 Ω
3. Reinstall the GAUGE fuse.
NG: REPLACE FUSE

OK: Go to Next Step

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

Disconnect the D29 light control rheostat connector.

Fig 1: Identifying Light Control Rheostat Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the voltage.

Standard voltage

TESTER CONNECTION SPECIFIED CONDITION

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

Reconnect the light control rheostat connector.

OK: Go to step 5

NG: Go to Next Step

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

Disconnect the D29 light control rheostat connector.

Fig 2: Identifying Main Body ECU And Light Control Rheostat Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the 4P main body ECU connector.

Measure the resistance.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

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

Reconnect the light control rheostat connector.
Reconnect the main body ECU connector.

NG: REPLACE MAIN BODY ECU

OK: Go to Next Step

INSPECT LIGHT CONTROL RHEOSTAT

Remove the light control rheostat but without disconnecting the connector.

Fig 3: Identifying Light Control Rheostat Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Turn the ignition switch ON.

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

ITEM CONTENTS CHART

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 Fig 3 .

HINT:

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

Reinstall the light control rheostat.

NG: REPLACE LIGHT CONTROL RHEOSTAT

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - [Aring] @LIGHT CONTROL RHEOSTAT)

Disconnect the D1 combination meter assembly connector.

Fig 4: Identifying Combination Meter Assembly And Light Control Rheostat Connector Terminals

Disconnect the D29 light control rheostat connector.

Measure the resistance.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

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

Reconnect the combination meter assembly.
Reconnect the light control rheostat connector.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE COMBINATION METER ASSEMBLY