Audi Repair: Instrument cluster lights, radio panel, excessive load

Question
QUESTION: I have a 2000 Audi A4. Recently the whole instrument cluster lights start to go off and on every few seconds when the cars is running. This also includes the radio panel lights during the night time when the head light is on. It must be a poor connection some where. Can anybody help? Thanks,

ANSWER: Does the dimmer switch still work?  Does changing the light level in the cluster change the behaviour?  Let me know,  Jan

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QUESTION: Thanks, for the response. The dimmer switch worked. I have done more test: With the head light switch on (the radio panel light becomes a better monitor for this test) and turn the ignition key to the first position, all lights stay on with no problem. But when I turn the ignition key to the second position (without starting the engine) then the problem occurred. Any idea? Thanks,

ANSWER: That is a useful test.  Now you know that the problem is probably associated with the ignition switch contacts.  There is also a chance that the ignition circuit itself is causing an excessive load but this is less likely.  If you wiggle the key in the second position can you see if the behaviour changes?  Let me know,  Jan

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QUESTION: Well, I was wrong. Even with the ignition key in the first position it failed too. (I waited long enough). The frequency of failure seems related to the temperature of the car. The cluster lights failed every second when I started the car. After I have used the car for an hour then the frequency slow down to every minute. Is this info help? Thanks,

Answer
Can you hear a relay clicking at the same time the lights switch on and off?  It sounds like the current draw has an effect on the frequency; are you sure you did not replace a bulb with a christmas tree flashing bulb?  This is a strange problem,  Jan