I bought a climate control unit from a 1998 A4 to put into my 1996 A4, thinking it would work perfectly, and it does, except that the display does opposite what it is supposed to do. It is VERY bright when I turn the headlights on, when the headlights are off, it dims down as if the lights are on. Is this a known issue? I thought it would be compatible. Is there anything I can do to correct it?

 

Any takers?

 

i thought that when the lights go on it should be brighter cause its dark out, you dont need a bright display during the day thats just retarded

 

Your should have a bright display in the day and a dimmed one at night so it doesnt distract you. If you enter the diagnostic mode at night then youll see how bright it is during the day.

What happens when you dim ur instrument panel down with the instrument cluster dial?

 

Well, it dims down slightly, but not as low as the rest of the dash. The weird thing is when I turn the lights off, the display goes darker than it does with the dimmer switch all the way down with the lights on. Is there something I can change or do in this diagnostic mode? Or is it just going to work this way since my car is 1996 and it is from a 1998. I notice the buttons and casing are different, but they are otherwise identical.

 

Well i was looking on my service manual and it says it recieves a signal from the instrument cluster to tell it how bright to go (as well as the sun sensor). If the signal it got from the insturment cluster was just based on resistance, then you could put a resistor in between to get it to dim, but the service manual says it sends a "Square signal wave" so I dont think it would be possible to modify the wire that goes to the instrument panel. I would think that maybe there is something wrong with your sun sensor, but that would be more likely if the screen stayed at one brightness and never changed. So im out of ideas.. sorry maybe someone else might be more help.