<VV> Still more Re: Temp/Pressure light problem.

[FrankCB]

Ned, 
     That's only true if the bulb is still in the socket when the wire is tested.  If the bulb is removed, the second wire (the one to the 2 sensors) will NOT be "hot" (i.e., it will show NO voltage) because it depends on the lamp filament to "carry" the voltage.  This is typical wiring for warning lamps that can be turned on by 2 (or more) different sources.  The problem with that is, of course, WHICH of the 2 caused the light to come on.  Has your engine overheated OR did it lose oil pressure???  It could even be BOTH.  But the major problem with these, IMHO, is the lack of WARNING that a problem is APPROACHING.  By the time the light comes on the problem has ALREADY happened.  And how do you tell which problem you have?  If you've lost all oil pressure, you must immediately shut down the engine.  But, on the other hand, if the engine has overheated, you probably want to keep the engine and fan running to help cool down the engine.  
     Frank Burkhard
     
In a message dated 12/15/09 09:26:34 Eastern Standard Time, aeroned writes:
No...the circuit is completed at the sender to ground. Therefore, the wire is "hot" everywhere. 

Ned