Stereo & Electronics - Dash lights go out when seat belt is used??

Anyone familiar with the indiglo gauges? I had one of my friends solder the 12 volt and the ground wires to my BCM under the dash, and when the driver's seatbelt is used the dash lights go out, when you take it off they go back on. I checked to see if i had tail lights, they still work. Could it be that the ground should have been grounded to the body? The power wire is run into the Illumination power wire so when you turn the parking lights on the gauges go on. The ground is run into the Illumination ground wire. I hope this helps. The car is a 2000 camaro SS.

Thanks for the help and the extra information, I will re route that ground. thanks for the help.

you said it, change the ground point of the gauge panel, a chassis groud should be just fine. The wire going to the seatbelt mech is a positve lead, when you put the seatbelt in it completes the circuit feeding a positive signal through your ground lead to your gauge panel.