I have a 2004 and a 2005 Prius that are Taxis. They both intermittently lose their Speedometer and all dummy lights. The cars still run fine, but the taxi meters lose signals from speedometer and only run on time. Also, the trunk does not open. Sometimes I can't even turn the cars off. I've spent over $1500 at Toyota dealerships and still have no fix. They assured me that the taxi meters installation was correct and said they have never had that problem ever before even after calling head office. Does anyone know what this problem is and how to solve it? Or has this happenned to anyone else?