Diagnosis of ignition cables
Since ignition cables are subject to high levels of stress, the cables must be inspected regularly and replaced at the first sign of ageing. The external appearance of an ignition cable can provide information about the cause of defect in the case of damage.
Therefore, a thorough visual inspection of the ignition cable is the first step in diagnosing cases of damage. For example, it can be recognised from a deformed plastic sleeve that the ignition cable was most likely not routed properly in the engine bay.
Externally sound ignition cables can be tested with a so-called multimeter. Using this important diagnostic tool the resistance of the ignition cable can be read off and compared with the permissible resistances.