Diagnosis & Repair

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.

Remove the engine room ECU cover. Start the engine. Measure the voltage between terminal FPR of the ECM connector E3 and body ground while racing the engine. See Fig 1. With STA ON, voltage should be 9-14 volts. With STA OFF, voltage should be 0-3 volts. If okay, check and replace ECM. If not okay, go to next step.

Fig 1: Checking Voltage At ECM Terminal FPR
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Check operation of fuel pump relay. See MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. Replace as necessary. If okay, repair or replace harness or connector between fuel pump relay and ECM.