P0183

DTC P0183

CIRCUIT DESCRIPTION
The fuel temperature (FT) sensor is a variable resistor. The FT sensor has a signal circuit and a low reference circuit. The FT sensor measures the fuel temperature of the fuel. The engine control module (ECM) supplies 5 volts to the FT signal circuit and a ground for the FT low reference circuit. When the FT 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 FT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the FT signal circuit. If the ECM detects an excessively high FT signal voltage, indicating a low temperature, this DTC will set.

Condition for Running the DTC
- DTCs P0182, P0602 and P0603 are not set.
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.
- The engine is running.

Condition for Setting the DTC
- The ECM detects that the FT sensor signal voltage is more than 4.8 volts for longer than 1 second.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) 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 Freeze Frame/Failure Records.
- The ECM uses a FT substitution of 77 °F (25 °C) when the DTC is set.
- The ECM uses a FT substitution of -20 °F (-29 °C) for engine starting.
- The ECM uses a FT substitution of 219 °F (104 °C) for engine running.
- The ECM limits fuel rail pressure within 11600 psi (80 MPa).
- The ECM closes the EGR valve and holds to close position.
- The ECM inhibits the cruise control.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when the diagnostic runs and does not fail. (12,000 lbs GVW)
- The ECM turns OFF the MIL when the diagnostic runs and does not fail. (Except 12,000 lbs GVW)
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
- Before starting a cold engine, FT sensor and engine coolant temperature (ECT) sensor temperature should be relatively close to each other.

If an intermittent condition is suspected, the following may cause an intermittent:
- FT sensor may have an intermittent open as it heats up.
- Poor connections
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation

Check for the following conditions:
- Poor connection at the ECM: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "Fuel Temperature Sensor" display on the scan tool with the engine running while moving connectors and the wiring harness related to the sensor. A change the in the display will indicate the location of the fault.

Test Description
The number below refers to the step number on the diagnostic table.
5. This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

DTC P0183
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

Step 2 - 6:

Step 7 - 13:

Step 14 - 15: