Airflow Sensor Position Indicator
- Loosen harness connector plug of airflow sensor position indicator to permit measuring of voltage at pins (do not disconnect harness connector plug). Start engine. Voltage at terminals No. 1 and 3 should be 4.5-5.5 volts. Voltage at terminals No. 1 and 2 should be .5-1.5 volts. If okay, go to next step. If voltage is not as specified, go to step 3).
- Stop engine and turn on ignition. Remove intake duct from airflow inlet of throttle body. By hand, slowly deflect airflow sensor plate downward, while measuring voltage between terminals No. 1 and 2. Voltage should increase steadily to 4.5-5.5 volts. If voltage is not to specification, replace airflow sensor. If voltage is to specification, test is complete.
- Stop engine. Check wires between airflow sensor position indicator and CIS-E control unit plug for continuity. See Fig 1 and Fig 2.Check wires for correct routing. Resistance should be zero ohms. If okay, go to next step. If not okay, repair open circuit.
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
- Start engine and run at idle speed until engine is at operating temperature. Turn off engine. Connect On-Off Ratio Tester (Bosch KDJE-P 600) to diagnostic socket, circuit TD. Diagnostic socket is located on left side of engine compartment. Start engine and run at idle speed. Tester needle should oscillate. If needle does not oscillate, check diagnostic socket. If needle oscillates, test is complete.
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.