my oil pressure (U225 cummins 5.9) gauge does not work, when I turn the key on it goes all the way over to the highest position. any ineas what it might be...the gauge or the sensor and how do I check to see what is bad?<br/> I attached a pic of a sender and I don't know what it is for (red connectors on it) if I disconnect the wires the oil gauge does the same thing when...