Lights dim and then brighten on start up.

[Stuwey]

Dead cell? Got a multimeter?

[brad]

Dead cell? Got a multimeter?

+1 for a battery. Even though its only a couple of years old it could still be playing up, especially if there are other electrical issues like the battery being drained constantly or the alternator not charging it properly.

I think it would be worth getting the battery tested and check that the alternator is putting out enough volts. Start with that ( as you can generally get them tested for free) and then work back from there.

Both these +++

There's no point just doing a visual. You need to get out the multimeter & check the resistance or volt drop between 2 points as the corrosion can be within a cable (esp an earth or main power feed cable). Also clean the connector to the electric power steer