1996 PCED OBDI
SECTION 18: Diesel Diagnosis — 7.3L DI Engine

Y: Engine Oil Temperature (EOT) Sensor
Introduction
  Y: Pinpoint Tests  





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)
Test PointsSpec.Comments
A to Grd<5 ohmsResistance to ground. If greater than 5 ohms the harness is open
B to Grd>5 ohmsResistance less than 5 ohms indicates a short to ground



CONNECTOR VOLTAGE CHECKS
(CHECK WITH SENSOR CONNECTOR DISCONNECTED AND IGNITION KEY ON)
Test PointsSpec.Comments
A to Grd0-.25 voltsIf greater than .25 volts signal wire is shorted to VREF or battery
B to Grd4.6-4.9 voltsPull up voltage, if no or low voltage circuit has open or high resistance



HARNESS RESISTANCE CHECKS
(CHECK WITH BREAKOUT BOX INSTALLED ON HARNESS ONLY)
Test PointsSpec.Comments
No. 91 to A<5 ohmsResistance from sensor connector to 104-pin connector
No. 38 to B<5 ohmsResistance from sensor connector to 104-pin connector

DTC Descriptions

Circuit Faults:

0197 = EOT sensor circuit low input.

0198 = EOT sensor circuit high input.

System Faults

0196 = 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).







k OhmsEOT (Volts)°C°F
1.190.53120248
1.560.67110230
2.080.86100212
2.801.0990194
3.841.3780176
5.341.7270158



k OhmsEOT (Volts)°C°F
7.552.1160140
10.932.5650122
16.113.0140104
24.253.443086
37.343.822068
58.994.131050

 

 

  Y: Pinpoint Tests