Coolant temperature sensor/sender

Hey guys,

A few questions about the Series I L67 coolant temperature sensor.

Is it indeed a sender as well as a sensor?

What does it mean exactly when the scanner says your coolant temperature is -39F when it's 55F outside? I vaguely remember reading something about such an extreme temperature reading at one point but can't find what I read. Does that mean the sensor has gone bad?

Thanks all,

-Andrew Z

Regarding automotive parts, a sender and sensor are used interchangeably, like 'alternator' and 'generator'. Technically, there is a difference between the two. A quick search found this definition, which makes good sense to me:

In the automotive arena, there is a generally accepted convention regarding the terms "sender" and "sensor".

Simply put, a "sensor" is a device that provides an input signal to the Engine Control Module (ECM) or Powertrain Control module (PCM), and is tasked with monitoring a specific condition and providing the ECM/PCM with ongoing information regarding that condition. The ECM/PCM uses that information in formulating its control output(s) to various engine and/or powertrain devices. For example, a PCM may use a crankshaft position sensor's output to determine the triggering of the ignition control module, thus driving the timing of the spark to the spark plugs. However, the crank position sensor input to the PCM is normally also used as a factor in other calculations made by the PCM, as is the case with most of the many sensor inputs received by the PCM.

In the automotive sense, a "sender" is a device that has a direct control over its output device. Some examples would be a fuel level gauge, an oil pressure gauge, or a coolant temperature "idiot" light. In each of these examples, the output device (e.g., the gauge or the light) and its associated "sender" are usually components in discrete circuits.

Regarding the very low temp reading, -39ºF would almost certainly mean the circuit wiring or sensor on that circuit is broken, causing an open circuit. The ultra-high resistance mimics the condition that would "sense" such an extreme temperature reading, A number like -39 is probably the max negative number, so the sensor is effectively "pegged" cold.

Thanks for all the information Aaron! Much appreciated.

So, do you think I may have messed up the readings from the sensor in some way? I ended up tapping off the signal line to the PCM to feed my Lesabre's temp gauge, but I guess it doesn't work that way.

You will completely mess up the expected resistance from the sensor to the PCM if you add another gauge to the same wire. Resistance is a precision measurement.

damn i scewed up huh? Thats ok i can fix it


thanks guys!

Hey everyone - update. I fixed the coolant temperature circuit. All is well on the scanner! I can't believe I did that...

Anyway, I now have a new issue. No coolant temperature gauge. Does anyone know what my options are to get the gauge to operate? Probably the most accurate thing would be to tap in another temperature sender somewhere, but where?

Any other ideas?

Thanks guys! I appreciate it!