Circuit Description

WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

The fuel pump speed is controlled at 2 steps (high speed, low speed) according to the condition of the engine (starting, light load, heavy load).

When the engine starts, the ECM turns the fuel pump relay OFF to operate the fuel pump at high speed. After the engine has started, during idling or when the load is light, the ECM turns the fuel pump relay ON to operate the fuel pump at low speed. When the intake air increase (heavy load), the ECM turns the fuel pump relay OFF to operate the fuel pump at high speed. There are two fuel pumps. The ECM switches from main to sub or sub to main every time the ignition switch is turned ON and OFF.

Fig 1: DTC P0230 Chart

HINT:

This diagnostic chart is based on premise that engine is started. If the engine is not started, proceed to problem symptoms table on PROBLEM SYMPTOMS TABLE .