Inspection Procedure

WARNING: This page is about a different car, the 2002 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

SERVICE CHECK MODE(GATEWAY ECU)
1. Service check
  1. Activate the diagnosis system and read out the check results in the service check mode.
  Standard: "NCON (No Connection) " or nothing displayed
1. NG: GO TO MULTIPLEX COMMUNICATION SYSTEM (See HOW TO PROCEED WITH TROUBLESHOOTING )
2. OK: GO TO NEXT STEP

CHECK WIRE HARNESS OR CONNECTOR (RADIO RECEIVER ASSY-GATEWAY ECU)

Disconnect the radio receiver assy and gateway ECU.

Check continuity wire harness.

Standard:

RADIO RECEIVER ASSY AND GATEWAY ECU TERMINALS CONTINUITY

Terminal	Condition	Specified condition
TX+ - GTX+	Constant	Continuity
TX-- GTX-	Constant	Continuity
TXS+ - Body ground	Constant	No continuity
TXS-- Body ground	Constant	No continuity

NG: GO TO COMBINATION METER SYSTEM (SEE HOW TO PROCEED WITH TROUBLESHOOTING )
OK: GO TO NEXT STEP

INSPECT COMBINATION METER ASSY (SPEEDOMETER) (SEE MALFUNCTION IN SPEED METER )
1. NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
2. OK: GO TO NEXT STEP
INSPECT STEREO COMPONENT AMPLIFIER ASSY (SPD)
1. Check voltage.
  1. Shift the shift lever to neutral.
  2. Jack up one of the front wheel.
  3. Turn ignition switch ON.
  4. Measure voltage between terminals SPD and GND of stereo component amplifier when the front wheels are turned slowly.
  Voltage is generated intermittently.
  
  Fig 3: Stereo Component Amplifier Assy Terminals Voltage Graph
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 4: Identifying Stereo Component Amplifier Assy Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: REPAIR OR REPLACE WIRE HARNESS OR CONNECTOR
2. OK: CHECK AND REPLACE STEREO COMPONENT AMPLIFIER ASSY