Electronic Idle Speed Control (190E 2.6L & 300 Series)

Connect Test Cable (103 589 00 63 00) to idle speed air valve and on-off ratio tester. Push IR 100% button. With engine at idle and at normal operating temperature, tester should read a minimum value of 36-50% at 650-750 RPM. If reading is as specified, test is complete. If tester reading is not as specified, proceed to next step.
If readout was 50-100%, check for air leak or air restriction. If readout was 0-35%, turn engine off. Disconnect electrical plug from idle speed air valve. Briefly apply battery voltage to idle speed air valve. When idle speed air valve switches, a clicking sound should be heard or it should be felt with hand. If valve does not switch, replace idle speed air valve. If valve clicks or switching could be felt, proceed to next step.
To test voltage supply, turn ignition on. Voltage on terminal No. 2 of idle speed air valve electrical plug should be about 12 volts. If not, repair circuit as required. If voltage is as specified, test input signals of coolant temperature sensor, airflow sensor position indicator, idle speed contact on throttle valve switch or CIS-E control unit.