Speed Signal Error

WARNING: This page is about a different car, the 2006 Lexus GS 430 and 2006 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

CHECK VEHICLE SENSOR (NAVIGATION CHECK MODE)
1. Enter the "Navigation Check" mode (Vehicle Sensors) (see NAVIGATION CHECK MODE ).
2. While driving the vehicle, compare the "SPD" indicator to the reading on the speedometer. Check if these readings are almost equal.
  OK : The readings are almost equal.
NG : REPLACE NAVIGATION ECU

Fig 1: Identifying Vehicle Sensors Display Screen
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OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN DIAGNOSTIC TROUBLE CODE CHART