Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

CHECK AND OPERATE AGAIN
1. Check and operate again.
  1. Turn ignition switch to OFF.
    Standard: Navigation system is normal.
1. OK: NORMAL
2. NG: Go to next step.
NAVIGATION CHECK MODE (VEHICLE SPEED SIGNAL)
1. Perform navigation check.
  1. Start the diagnosis system and read result for vehicle signal check mode.
  Standard: Input signal is normal (SPD).
1. OK: CHECK AND REPLACE NAVIGATION ECU
2. NG: Go to next step.
INSPECT NAVIGATION ECU (SPD)
1. Remove the navigation ECU with connectors still connected.
2. Check voltage.
  1. Shift the shift lever to neutral.
  2. Jack up one of the rear wheel.
  3. Turn ignition switch ON.
  4. Measure voltage between terminals SPD and GND1 of navigation ECU when the rear wheels are turned slowly.
    
    Fig 1: Identifying Terminals SPD & GND1 Of Navigation ECU
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  Voltage is generated intermittently.
  
  Fig 2: Oscilloscope Pattern - Terminals SPD And GND1 Of Navigation ECU
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. OK: CHECK AND REPLACE NAVIGATION ECU
2. NG: REPAIR OR REPLACE HARNESS OR CONNECTOR