Y: Engine Oil Temperature (EOT) Sensor
Introduction
Introduction
1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
Y: Engine Oil Temperature (EOT) Sensor Introduction | Y: Pinpoint Tests |
The EOT (Engine Oil Temperature) sensor is a thermistor type sensor that has a variable resistance that changes when exposed to different temperatures. When interfaced with the PCM it produces a 0 to 5 volt analog signal that will deduce temperature.
Cranking Fuel Quantity/Timing Control — The EOT 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 158°F (70°C) 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 — Engine oil temperature. The glow plug relay and lamp ON time are controlled by oil temperature.
An EOT signal that is detected out of range (high or low) by the PCM will cause the PCM to ignore the EOT signal and assume an engine oil temperature of -29°F (-20°C) for starting and a temperature of 212°F (100°C) for engine-running conditions. The CHECK ENGINE light will also be illuminated as long as the condition exists.
After removing connectors always check for damaged pins, corrosion, loose terminals, etc.
| Test Points | Spec. | Actual | Comments |
|---|---|---|---|
| A to Grd | <5 ohms | Resistance to ground. If greater than 5 ohms the harness is open | |
| B to Grd | >5 ohms | Resistance less than 5 ohms indicates a short to ground |
| Test Points | Spec. | Actual | Comments |
|---|---|---|---|
| A to Grd | 0-.25 volts | If greater than .25 volts signal wire is shorted to VREF or battery | |
| B to Grd | 4.8-4.9 volts | Pull up voltage, if no or low voltage circuit has open or high resistance |
| Test Points | Spec. | Actual | Comments |
|---|---|---|---|
| No. 91 to A | <5 ohms | Resistance from sensor connector to 104 pin connector | |
| No. 38 to B | <5 ohms | Resistance from sensor connector to 104 pin connector |
Circuit Faults:
117 = Signal was less than 0.15 volts for more than 0.20 seconds.
118 = Signal voltage was greater than 4.79 volts for more than 2 seconds.
System Faults
116 = Engine oil temperature less than 176°F (80°C) during KOER (KOER access denied).
847 = Engine oil temperature greater than 242°F (117°C) during KOER (KOER access denied).
| k Ohms | EOT (Volts) | °C | °F |
|---|---|---|---|
| 1.19 | 0.53 | 120 | 248 |
| 1.56 | 0.67 | 110 | 230 |
| 2.08 | 0.86 | 100 | 212 |
| 2.80 | 1.09 | 90 | 194 |
| 3.84 | 1.37 | 80 | 176 |
| 5.34 | 1.72 | 70 | 158 |
| 7.55 | 2.11 | 60 | 140 |
| 10.93 | 2.56 | 50 | 122 |
| 16.11 | 3.01 | 40 | 104 |
| 24.25 | 3.44 | 30 | 86 |
| 37.34 | 3.82 | 20 | 68 |
| 58.99 | 4.13 | 10 | 50 |
| Y: Pinpoint Tests |