Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

Check voltage between terminals +B, ACC and GND of navigation ECU.

Disconnect the connector from the navigation ECU.

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

Standard:

+B, ACC AND GND OF NAVIGATION ECU TERMINALS VOLTAGE

Tester connection	Condition	Specified condition
+B1 - GND	Always	10 to 14 V
ACC - GND	Ignition SW ACC	10 to 14 V

Fig 1: Checking Voltage Between Terminals +B, ACC And GND Of Navigation ECU

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OK: Proceed to next circuit inspection shown in. (See PROBLEM SYMPTOMS TABLE
NG

Check continuity between terminal GND of navigation ECU and body ground.

Disconnect the connector from the navigation ECU.

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

Standard:

NAVIGATION ECU GND TERMINAL AND BODY GROUND RESISTANCE

Tester connection	Condition	Specified condition
GND - Body ground	Always	Below 1 Ω

Fig 2: Checking Continuity Between Terminal GND Of Navigation ECU And Body Ground

OK: Repair or replace harness or connector between navigation ECU and fuse.
NG: Repair or replace harness or connector between navigation ECU and body ground.