Attention: When the battery is disconnected, the information in the electronic memory devices, such as the engine trouble memory or the radio security code memory, is erased. When disconnecting the battery, follow the instructions in section "Removing and installing the battery".
Model 518i: remove the ignition wire cover on the cylinder head (see fig. W-1218).
Disconnect spark plugs and ignition wires from distributor. Connect an ohmmeter and measure the resistance. The set value is about 6 kOhm.
Disconnect the wire between the ignition coil and the distributor and measure the resistance. The set value is about 2 kOhm.
All models except 518i: If there is a deviation from the specified value, unscrew the tip from the ignition wire and measure the resistance. See the table on the next page for the set values.
With increased resistance, clean the wire connection contacts and repeat the test. If necessary, replace the wire.
Bend the ignition wires near the spark plug tips at a large angle and check for cracking of the wires. If required, replace all ignition wires at once.