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Lotus Service Notes
Section EMP Page 35 Idle Speed Control P0506 P0507 P0508 P0509 P0506 Idle Air Control System RPM Lower Than Expected P0507 Idle Air Control System RPM Higher Than Expected P0508 Idle Air Control System Circuit Low (prior '06 M.Y.) P0509 Idle Air Control System Circuit High (prior '06 M.Y.) Description Prior to '06 M.Y. the ECU controls the air entering the engine with an idle air control (IAC) valve. To increase the idle the ECU commands the IAC to open up. This allows more air to bypass the throttle blades. To decrease the idle speed the ECU commands the IAC to close up. This will reduce the amount of air bypassing the throttle body. The ECU performs low and high circuit checks when it is activating the component. For '06 M.Y. onwards, the electronically controlled throttle needs no IAC, as the ECU commands the throttle valve itself to control idle speed. Component connections (prior to '06 M.Y.) Connector Description ECU Pin ECU Connector 1 Idle air control value 35 52 Way 2 Battery Voltage - - 3 Ground - - Malfunction Criteria P0506 – This code is set if the engine fails to achieve the desired idle speed by more than 100 rpm. P0507 – This code is set if the engine fails to achieve the desired idle speed by more than 200 rpm. P0508 – This is set when the ECU does not get the expected feedback (prior to '06 M.Y.). P0509 – This is set when the ECU does not get the expected feedback (prior to '06 M.Y.). Enable Criteria: • Engine at idle speed • Battery Voltage between 10 – 16 V • Idle speed learn limit ± 15% • Timer expired 5 seconds Monitor: Continuous Potential failure modes: • Throttle body sticking (not fully closing) (prior to '06 M.Y.) • Connector / wiring corroded or loose connections (prior to '06 M.Y.) • Throttle linkage / cable binding (prior to '06 M.Y.) • Induction system air leak • Excessive engine load from front end accessory drive system, e.g. water pump seizing Notes: The MIL will be illuminated if the fault is present for 2 consecutive trips. |