One problem related to interior rearview mirror has been reported for the 2003 GMC C2500. The most recently reported issues are listed below.
The thermometer in the mirror that reads the outside temperature does not work properly when the snowplow is attached to the vehicle. When snowplowing, it is critical to know the freezing point, and is the time that the thermometer is needed the most. Giving an inaccurate temperature (above freezing when it is really below freezing) will cause skidding accidents. The dealer and the GMC factory have acknowledged the "design defect" but have failed to correct it or offer a refund for the cost of the thermometer option. Dealer has replaced tempertature sensor, but its location is what prevents it from working when the snowplow is attached. I have asked the dealer to relocate the sensor, but they said they cannot alter the vehicle's design. This is a design defect on all 2003 & 2004 GMC pick up trucks with snowplows attached, and yet GMC has offered to do nothing about it. Bear in mind, these vehicles are being marketed with "cold climate" packages and dealer installed snowplows. A skidding accident can and will result when the thermometer reads 45 degrees farenheit and it is actually 28 degrees farenheit outside.