Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

Check voltage between terminals ECUB and GND of ECU connector.
PREPARATION:

Remove ECU with connectors still connected.

CHECK:

Measure voltage between terminals ECUB and GND of ECU connector.

OK:

Voltage: 9 - 16 V

Fig 1: Measuring Voltage Between Terminals ECUB And GND Of ECU Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. OK : Proceed to next circuit inspection shown on the problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
2. NG : Go to next step.
Check continuity between terminal GND of ECU connector and body ground.
CHECK:

Measure resistance between terminal GND of ECU connector and body ground.

OK:

Resistance: 1 kΩ or less

Fig 2: Measuring Resistance Between Terminal GND Of ECU Connector And Body Ground
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG : Repair or replace harness or connector.
2. OK : Go to next step.
Check MPX-B3 fuse.
PREPARATION:

Remove MPX-B3 fuse from passenger side J/B.

CHECK:

Check continuity of MPX-B3 fuse.

OK:

Continuity
1. NG : Check for short in harness and all components connected to MPX-B3 fuse.
2. OK : Check for open circuit in harness and connector between ECU and battery (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).