Q The dipped beam headlamps on my 53-plate Jaguar S-TYPE 3.0 are turning themselves off and on again intermittently. Turning the lights off and on again clears the problem temporarily. Recently, the side-lights have started suffering from the same problem. I can’t vouch for the main beam setting as I’ve never had it on after this problem arose. I’ve listened for any chattering relays, but can hear nothing. As I’m sure you’re aware, the dipped beam and the main beam on the S-TYPE are two separate units. Stephen Hayes
A You don’t say if the problem is occurring with the light switch set to the automatic position or in the override control positions of off, side and headlamps. If the switch is normally left in the automatic position, this may be the problem, which is also supported by the fact that switching the lights off and on again normally rectifies the fault.
Another possibility is that the wiring inside the dip/main beam stalk on the steering column has failed. This is something I have come across. Usually, one of the wires in the stalk fractures and will make and break the circuit at random. The operation of the stalk would need checking using a continuity meter to confirm that this is the problem.
The third area to check is the wiring loom which runs across the front of the vehicle. Inspect the earth connections to the crossmember and also the condition of the wiring loom. Corrosion here can cause problems within the lighting circuit.