P0183

DTC P0183

CIRCUIT DESCRIPTION
The fuel tank temperature (FTT) sensor is a variable resistor that measures the temperature of the fuel in the compressed natural gas (CNG) fuel tank. The fuel injector control module (FICM) supplies 5 volts to the FTT signal circuit and supplies a ground to the low reference circuit. The FICM monitors the FTT sensor voltage and communicates the data to the powertrain control module (PCM) by a dedicated pulse width modulated (PWM) circuit. This DTC sets when the FTT signal voltage is above the normal operating range of the sensor.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0183 Fuel Temperature Sensor Circuit High Voltage

CONDITIONS FOR RUNNING THE DTC
- The ignition is ON.
- The intake air temperature (IAT) is more than -10°C (+14°F).
- DTCs P0112, P0113, or P1207 are not set.

CONDITIONS FOR SETTING THE DTC
- The FTT sensor voltage is more than 4.95 volts.
- The condition exists for more than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- 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.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- Use the Temperature vs Resistance table in order to test the FTT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in a driveability condition. If the engine has sat overnight, the FTT sensor and the IAT values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to Fuel Tank Temperature (FTT) Sensor Output Voltage vs Temperature Resistance.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Step 1 - Step 8:

Step 9 - Step 13:

The numbers below refer to the step numbers on the diagnostic table.
4. 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.
8. This step tests the signal circuit of the FTT sensor for a short to another 5-volt reference circuit.