I'm told my 2001 ECU may be causing this problem. When I turn on the key, without starting, the oil pressure goes up to normal operating pressure. When I start up -- the gauge doesn't move until I turn the truck off. There is no other signs of poor oil pressure( dealer put gauge on it and says its running normal) and the oil/filter are changed as directed. Is it true the oil pressure gauge is run by the ECU? Don't want to buy a new ECU but I guess I should be getting a mechanical oil gauge installed. Any comments are appreciated.