Checking the engine control unit

1. Connect thin wire (for wire harness: MB991223 or paper clip) to the voltmeter probe (pic. 8.1).



2. Plug a thin wire from the side of the cable connection to the connector terminal of the engine control unit and measure the voltage, comparing it with the values in table 8.5. The sectional view of the engine control unit connector is shown in fig. 8.2.



3. If the voltmeter shows a value that does not match the specified value, check the sensor, the corresponding wire and the actuator (actuator), and, if necessary, repair or replace the defective element.

4. After repair or replacement, check with a voltmeter to see if the problem is fixed.

Table 8.5. ECM terminal voltage test chart