Circuit Description
The fuel temperature sensor is a variable resistor. The fuel temperature sensor has a signal circuit and a low reference circuit. The fuel temperature sensor measures the fuel temperature of the fuel. The engine control module (ECM) supplies 5 volts to the fuel temperature signal circuit and a ground for the fuel temperature low reference circuit. When the fuel temperature sensor is cold, the sensor resistance is high. When the fuel temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the fuel temperature signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the fuel temperature signal circuit. If the ECM detects an excessively high fuel temperature signal voltage indicating a low temperature, this DTC will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0183 Fuel Temperature Sensor Circuit High Voltage
Conditions for Running the DTC
| • | The ignition switch is ON. |
| • | The battery voltage is between 10-16 volts. |
Conditions for Setting the DTC
The ECM detects that the fuel temperature signal voltage is more than 4.8 volts.
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) and Reduced Engine Power indicator lamp, if fitted, when the diagnostic runs and fails. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
| • | The ECM uses fuel temperature -29°C (-20.2°F) condition for starting the engine. |
| • | The ECM uses fuel temperature 90°C (194°F) condition for the engine running. |
| • | The ECM limits the fuel injection quantity for fail-safe operation. |
| • | The ECM closes the exhaust gas recirculation (EGR) valve and holds the EGR valve to a closed position. |
| • | The ECM inhibits cruise control. |
Condition for Clearing the DTC
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Before starting a cold engine, the fuel temperature sensor and the intake air temperature (IAT) sensor temperature should be relatively close to each other. |
| • | Use the Temperature vs. Resistance table to test the fuel temperature sensor at various temperature levels to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability concerns. Refer to Temperature Versus Resistance . |
| • | If an intermittent condition is suspected, the following may cause an intermittent: |
| - | Poor connections |
| - | A misrouted harness |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | Inspect for the following conditions: |
| - | Poor connection at ECM--Inspect the harness connectors for the following conditions: |
| • | Backed-out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wire connection |
| - | Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the Engine Coolant Temperature display on the scan tool while moving the connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
3 |
Is the DMM voltage more than the specified range? | 4.5-5.5 V | Go to Step 4 | Go to Step 5 | ||||
4 |
Important: The fuel temperature sensor may be damaged if the circuit is shorted to a voltage source.
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||
Is the Fuel Temperature Sensor parameter more than the specified value? | 135°C (275°F) | Go to Step 9 | Go to Step 6 | |||||
6 |
Is the Fuel Temperature Sensor parameter more than the specified value? | -44.7°C (-48.4°F) | Go to Step 8 | Go to Step 7 | ||||
7 |
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||
8 |
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||
9 |
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||
10 |
Important: The fuel temperature sensor may be damaged if the circuit is shorted to a voltage source.
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 | ||||
11 |
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 | ||||
12 | Replace the fuel temperature sensor. Refer to Fuel Injection Pump Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
13 |
Important: The new ECM must be programmed. Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 | ||||
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | ||||||
