Diagnosis & Repair

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

Remove ETCS fuse from the engine room No.1 relay block. See Fig 1. Check continuity of fuse and replace as necessary. If fuse is okay, go to next step.

Fig 1: Identifying ETCS Fuse Location
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Check the voltage between terminal E1 of ECM E3 connector and +BM of ECM E6 connector. See Fig 2. If 9-14 volts are present, check and replace ECM. If 9-14 volts are not present, go to next step.

Fig 2: Checking Voltage Between ECM E3 & E6 Connector Terminals E1 & BM
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Remove the ETCS fuse from the engine room No. 1 relay block. See Fig 1. Disconnect the ECM E6 connector. See Fig 3. Check continuity between the wire harness side connectors. Continuity should be present between ETCS fuse terminal 2 of relay block and +BM (V11-2). Continuity should not be present between ETCS fuse terminal No. 2 of relay block or +BM (V11-2) and ECM E3 connector terminal E1.

Fig 3: Checking Continuity With ECM E6 Connector Disconnected
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect battery positive terminal. Check continuity between wire harness side connectors. Continuity should be present between battery positive terminal and ETCS fuse terminal No. 1 of relay block. Continuity should not be present between battery positive terminal or ETCS fuse terminal No. 1 of relay block and ECM E3 connector terminal E1. If okay, replace ECM. If not okay, repair or replace harness or connector.