Caution: When the battery is disconnected, the information in the electronic memory devices, such as the engine fault memory or the radio security code memory, is erased. When disconnecting the battery, follow the instructions in the section "Removal and installation the battery".
Model 518i: Remove the spark plug wire cover on the cylinder head (see Fig. W - 1218).
Disconnect the spark plug tips and spark plug wires from the distributor. Connect an ohmmeter and measure the resistance. The specified value is about 6 kOhm.
Disconnect the wire between the ignition coil and the distributor and measure the resistance. The specified value is about 2 kOhm.
All models except 518i: If the value deviates from the specified value, unscrew the tip from the ignition wire and measure the resistance. For specified values, see the table on the next page.
If the resistance is increased, clean the wire connection contacts and repeat the test. If necessary, replace the wire.
Bend the spark plug wires at a large angle near the spark plug tips and check for cracks in the wires. If necessary, replace all the spark plug wires at once.
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