Crown SC4000. Almost consistently throws the -04 release parking brake code after 5 seconds of travel. Sometimes it will run fine but usually just have to throw it back into neutral and drive every 5 seconds. Figured it was a sensor so tried unplugging the on under the dash for the parking brake and also one under the brake lever with no change. Also tried loosening parking brake drastically in case it was just barely pulling somewhere. Open to other ideas to diagnose.