Contents: Checking the control device ↡ Checking the ignition coil ↡ Checking the additional resistance ↡
Checking the control device
The test is performed with the engine off and the ignition on.
The voltage value when the breaker contacts are closed:
- on the ignition coil terminal 15 - 3.6...4.6 V.
- on the connection panel terminal TD max 0.3 V (maximum voltage drop across breaker contacts).
Voltage value when the breaker contacts are open:
- on all terminals ignition system battery voltage (minus max 0.4 voltage loss between battery and ignition system).
Checking the ignition coil
Disconnect the wires from the ignition coil. The resistance of the primary winding, measured between terminals "1" and "15" at +20°C is 0.38...0.43 Ohm. Terminals "1" and "15" should not be connected to ground. Use a conventional measuring bridge for measurements. The ranges of a conventional multi-position measuring device are not accurate for these measurements. At an ignition coil temperature of 80°C, the resistance value increases by 25%.
Original material on the website mercedesman
Checking the additional resistance
Disconnect the wire. Check for ground contact. Using a measuring bridge, measure:
- nominal value 0.42...0.47 Ohm at +20°C resistance (2);
- nominal value 0.62...0.67 Ohm at +20°C resistance (3).