Very hard to see dash instruments in bright sunlight. Night time is fine. Manual control (background lighting) works fine. The "ambient light sensor" (Page 46 owners manual 2004 S60) has no affect. Does not matter - shine bright light into sensor or put black tape over sensor -- no change in illumination. Whenever tell a Volvo dealer about it -- they "roll" the manual control and say "see; it works fine". The problem is NOT the manual control -- the problem is the automatic sensor does not function (increasing illumination in bright light and decreasing it in darkness). The sensor is located in the center of the dash immediately below the A/C buttons. Any ideas???? Thanks.

 

it willdim the instrument cluster and make interion dash light dimmer when it's in the dark. when it's bright out it is supposed to make it bright . the dimmer switch is to adjust the brightness the sensor below a/c button??? the sensor on climate controls is an cabin temperature sensor not a light sensor. the light sensor locate under windshield close to the defroster vent in the center of the dash (intergrated to the LED for the alarm).

 

I know this reply is years later, but it might help someone. The light sensor is on the climate control in the centre under the "outlet level" buttons. Mine had, I thought stopped working, but after cleaning it with a duster it now adjusts the dash lighting as it should ! The sensor is so small I didn't even realise it was there being directly behind the gearshift if you have an auto.