Poor Idling
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
High Idle Speed
- Check A/C compressor signal circuit. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Check ECM power source circuit with ignition on. See ECM POWER SOURCE CIRCUIT (IGNITION KEYED) under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article.
Low Idle Speed
- Check A/C compressor signal circuit. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
- Check fuel pump control circuit. On all models, see FUEL PUMP CONTROL CIRCUIT under FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
Rough Idle
- Check engine compression. See BASIC DIAGNOSTIC PROCEDURES article.
- Check fuel pump control circuit. On all models, see FUEL PUMP CONTROL CIRCUIT under FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
Surging
- Check ECM power source circuit with ignition on. See ECM POWER SOURCE CIRCUIT (IGNITION KEYED) under COMPUTERIZED ENGINE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article.
- Check fuel pump control circuit. On all models, see FUEL PUMP CONTROL CIRCUIT under FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.