All DB & firmware updated as in UPMans post. The BCD536's replaced BCD996's, and the 996's have never had an issue. This is happening in 4 different wreckers who all have 2 batteries. The scanners work great, most with external speakers, some with internal speaker, but as soon as you start the vehicles, they ALL look like they are receiving (stop on scanning channels), but no audio comes out of the speakers. Direct wire to battery, ign sense wired, or cig wired. After this happens, you can turn them off, then back on, and they work fine. We just finished a 5th wrecker with 4 BCD536's in it 10 mins ago, and this 5th one is doing the same thing.