Diagnostic Aids

When K73 Telematics Communication Interface Control Module loses communication with the A10 Inside Rearview Mirror, the K73 Telematics Communication Interface Control Module will set DTC U1804 and the red OnStar system fault indicator "ON*!" will immediately turn on and fade out in 15 s. When the communication between the K73 Telematics Communication Interface Control Module and the A10 Inside Rearview Mirror resumes, DTC U1804 will become history. This is a normal operation. Do not replace the A10 Inside Rearview Mirror if DTC U1804 is stored in history. Just use scan tool to clear this history DTC.