1. For the gauge: This sensor sends a signal to the instrument cluster to show the engine temperature on your dashboard gauge. Its location is usually on the cylinder head, often near the thermostat housing. It's a single-wire sensor.
2. For the computer (ECM): This sensor provides the engine control module (ECM) with coolant temperature data for fuel injection and other engine management functions. This is usually a two-wire sensor, also located on the cylinder head, but potentially in a slightly different location than the gauge sensor.
Finding them:
Precise location varies slightly depending on the specific engine configuration and any modifications. However, the best approach is:
1. Consult a repair manual: A Haynes or Chilton manual specific to your 1994 Ford E150 6-cylinder will have diagrams showing the exact location of both sensors. This is the most reliable method.
2. Visual inspection: Once you have located the thermostat housing (usually at the front of the engine near the top), look closely in that area for sensors with wires plugged into them. The sensors are usually cylindrical and relatively small. One will likely have one wire, the other will have two.
3. Tracing the wires: If you can find the wire going to the temperature gauge in your instrument cluster, trace it back to its source. That's the sensor for the gauge. Similarly, tracing wires back to your engine's computer will help locate the ECM sensor.
Caution: The engine will be hot if it has recently run. Allow it to cool completely before working near it. Also, be mindful of potential coolant leaks.
