can i be charged for admitting to a crime (uuw), if my brother has already been charged for it?

My brother is going to trial next month for a uuw. they found it in my mothers car. he used a alias when arrested which was my name. If i testified that i was in possession of the vehicle can they charge me with the gun that was in it? my brother wasnt in the car he was down the street from it and they said he tossed the keys to it. that was their probable cause to break the glove compartment and arrest.