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 powertrain control module (PCM) supplies 5 volts to the FTT signal circuit. This DTC sets when the FTT signal voltage is below the normal operating range of the sensor.
DTC Descriptor
This diagnostic procedure supports the following DTC.
DTC P0182 Fuel Temperature Sensor Circuit Low Voltage
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The intake air temperature is more than -35°C (-31°F). |
Conditions for Setting the DTC
| • | The fuel tank temperature sensor voltage is less than 0.05 volt. |
| • | The condition exists for more than 5 seconds. |
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
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 intake air temperature values should display within a few degrees. If the temperatures are not within 3°C (5°F), refer to Fuel Temperature Sensor Output Voltage Versus Temperature Resistance . |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Alternative Fuels (Engine Controls) |
2 |
Does the scan tool indicate that the FTT is less than the specified value? | 0.05 V | Go to Step 4 | Go to Step 3 |
3 |
Does the DTC fail this ignition cycle? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Does the scan tool indicate that the FTT sensor voltage is more than the specified value? | 4.6 V | Go to Step 6 | Go to Step 5 |
5 |
Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 7 |
6 | Replace the FTT sensor. The FTT sensor is not serviceable separately from the high pressure lock-off (HPL). Refer to High Pressure Lock-Off Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- |
7 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls in the G/H Van Service Manual. Did you complete the replacement? | -- | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
