eyeteeth wrote:
Finally got around to digging out the box from the engine temp sensor I put in. NAPA part, TS6178SB.
Did some cross-checking ... that is the right sensor for your 440 engine.
I wanted to make sure you hadn't fallen victim to a somewhat common mistake when dealing with older vehicles.
Warning lights ... aka "idiot" lights ... use a simple switch which is closed when the temperature rises to a certain point. Gauges use a sensor that is a variable resistor, which increase and decrease circuit resistance based on the condition it's monitoring.
On vehicles where warning lights and gauges were alternative options, people sometimes use a switch with a gauge-equipped vehicle or vice versa.
The results are usually baffling ... a switch will cause a gauge needle to "peg" right or left, depending on the condition being monitored. For example, an oil pressure
switch will cause the oil pressure
gauge to show excess oil pressure until oil pressure build up enough to open the switch. (Temperature
switches are often thought to be defective in these cases because the switch stays open until engine temperature rises to excessive levels.)
On the other hand, a sensor will cause a warning light to glow with varying intensity due to the variable resistance the sensor creates in the circuit.
This problem arises in some cases when the counterperson doesn't realize the list the computer provides is not simply alternative parts. In other cases, the customer chooses a switch when they needed a sensor because the switches are typically less expensive than the sensors.
