Inspection Procedure

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

Check ECU-IG fuse .
PREPARATION: Remove the ECU-IG fuse from the instrument panel J/B.

Fig 1: Locating ECU-IG Fuse
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECK: The continuity of the ECU-IG.

OK: Continuity
1. NG: Check for short circuit in all harness and components connected to ECU-IG fuse (See attached wiring diagram).
2. OK: Go to 2.
Check for battery positive voltage when IG switch is OFF .
OK: Voltage: 9-14 V
1. NG: Charge or replace the battery.
2. OK: Go to 3.
Check voltage between terminals IG and PGND of EMPS ECU connector .
PREPARATION: Remove the EMPS ECU with connectors still connected.

CHECK: Turn the ignition switch ON and measure the voltage between terminals IG and PGND of EMPS ECU connector.

Fig 2: Locating EMPS ECU Terminals IG & PGND
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Voltage: 9-14 V
1. OK: Check and replace the EMPS ECU. HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE .
2. NG: Go to next step 4.
Check continuity between terminals PGND of EMPS ECU connector and body ground .
CHECK: Measure the resistance between terminals PGND of EMPS ECU connector and body ground.

Fig 3: Locating EMPS ECU Terminal PGND
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Resistance: 1 Ohm or less
1. NG: Repair or replace harness or connector.
2. OK: Check for open and short circuit in harness and connector between EMPS ECU and ECU-IG fuse. See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE .