5. FUEL INJECTION SYSTEM MXU 500EXi/MXU500i ELECTRIC CONTROL UNIT (ECU) REMOVAL/INSTALLATION Do not disconnect or connect the ECU connector during the ignition switch "ON"; it may cause the ECU damaged. The throttle position sensor (TPS) and idle air bypass valve (ISC) have to be reset when throttle body, MAP, TPS, ISC or ECU has been reinstalled. ECU Connector Disconnect the ECU connector and remove the ECU from the frame. Installation is in the reverse order of the removal. ECU connector remove procedure (Same as DOWNTOWN 125i) ECU connector install procedure 5-20