Test Notes

Signal Functions
The Engine Oil Temperature (EOT) sensor is a thermistor type sensor that has a variable resistance that changes when exposed to different temperatures. When interfaced with the Powertrain Control Module (PCM), it produces a 0 to 5 volt analog signal that will deduce temperature.

Cranking Fuel Quantity/Timing Control - The EOT sensor signal is used to determine the timing and quantity of fuel required to optimize starting over all temperature conditions.

Idle Speed - At oil temperatures below 70°C (158°F) low idle is incrementally increased to a maximum of 950 rpm.

Temperature Compensation - Fuel quantity and timing is controlled throughout the total operating range to ensure adequate torque and power is available.

Glow Plug Control - The glow plug relay and lamp ON time are controlled by engine oil temperature.

Detection/Management
An EOT sensor signal that is detected out of range (high or low) by the PCM will cause the PCM to ignore the EOT sensor signal and assume an engine oil temperature of -34°C (-29 °F) for starting and a temperature of 100°C (212°F) for engine-running conditions. The CHECK ENGINE light will also be illuminated as long as the condition exists.

NOTE: After removing connectors, always check for damaged pins, corrosion, loose terminals, etc.

Connector Checks To Ground (B-) (Check With Sensor Connector Disconnected And Ignition Key Off, All Accessories Off):

CONNECTOR CHECKS TO GROUND (B-) (CHECK WITH SENSOR CONNECTOR DISCONNECTED AND IGNITION KEY OFF, ALL ACCESSORIES OFF)

DTC Descriptions
Circuit Faults:
P0197 = EOT sensor circuit low input
P0198 = EOT sensor circuit high input

System Faults
P0196 (49 State except Econoline) = Engine oil temperature less than 74°C (165°F) or above 116°C (240°F) during KOER Cylinder Contribution Self Test (self test access denied).
P1184 (California and all Econoline) = Engine oil temperature less than 74°C(165°F) or above 116°C (240°F) during KOER Cylinder Contribution Self Test (self test access denied).