Volkswagen Fox - vehicle battery discharged

With the above-mentioned vehicle type, it is possible that the vehicle electrical system battery is completely discharged and it is no longer possible to start the engine. If the above-mentioned fault arises, a possible cause could be a faulty earth cable.

Loose or oxidised earth connections often cause malfunctions in electrical and electronic components, especially in components outside the vehicle interior. A defect in the vehicle earth, for example because of a heavily oxidised earth cable, can result in the alternator not charging the vehicle electrical system battery sufficiently, causing the latter to discharge even when the engine is running as a result of the consumers being switched on.

In the course of further troubleshooting, the voltage generated by the alternator under load, i.e. with consumers such as high beam, rear window heating and seat heating switched on, should be checked with a suitable measuring device.

To this end, the positive terminal of the measuring device can be connected to the positive terminal of the alternator and the negative terminal to the negative terminal of the vehicle electrical system battery. Approx. 14 V should be measurable here. Then connect the earth terminal of the measuring device to the housing of the alternator and the positive terminal to the battery positive terminal. Approx. 14 V should also be measurable here. If significantly lower voltages, for example 12.8 V, are measured during the latter measurement, this may indicate a faulty earth connection.

The next step in troubleshooting is to check all earth connections for cleanliness, corrosion and to see that they are firmly seated. If abnormalities are detected when checking the connections, replacing, repairing or cleaning the affected component can remedy the problem.

Once the cause of the fault has been rectified, delete the error memory and then carry out a test drive.