Disconnect the ground cable from the battery.
Remove the ignition coil cover. Disconnect the spring with a wide screwdriver, press the cover slightly and turn it back.
Remove the connections from the ignition coil.
If the plug is pressed out (see arrow) on the ignition coil, then replace the coil.
Check the resistance of the primary winding of the ignition coil by connecting an ohmmeter to terminals 1 and 15.
Check the resistance of the secondary winding by connecting an ohmmeter to terminals 1 and 4.
Connect the wires to the ignition coil.
Place the cover from the back, press and snap forward. Check the correct locations for the wires on the cover, use pliers to clamp the cover at the bottom.
(Article based on data from the website: mercedesman)
Connect the ground wire to the battery.
Caution: If the ignition coil is replaced, do not install a coil for a conventional contact ignition system under any circumstances. This may damage the commutator.