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 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 is more than -5°C (23°F). |
Conditions for Setting the DTC
| • | The fuel tank temperature sensor voltage is more than 4.95 volt (-22°C). |
| • | 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 . |
Important: This diagnostic may set in cold ambient temperatures if the IAT temperature increases while the tank remains cold. Conditions that can warm the IAT while the tank remains cold are extended idling or moving the vehicle into a warm environment. No repair is necessary if the stated conditions are suspected.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This diagnostic may set in cold ambient temperatures if the intake air temperature (IAT) increases while the tank remains cold. Conditions that can warm the IAT while the tank remains cold are extended idling or moving the vehicle into a warm environment. No repair is necessary if the stated conditions are suspected.
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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.
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This step tests the signal circuit of the FTT sensor for a short to another 5-volt reference circuit.
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 near the specified value? | 5 V | Go to Step 4 | Go to Step 3 |
3 |
Does the DTC fail this ignition cycle? | -- | Go to Step 5 | Go to Diagnostic Aids |
Measure the actual tank temperature with a thermometer. Is the fuel tank at a temperature colder than the value specified? | -21°C (-6°F) | Go to Step 14 | Go to Step 5 | |
Important: If the fuse opens, repair the short to voltage on the FTT signal circuit. Does the scan tool indicate that the FTT is at the specified value? | 0 V | Go to Step 8 | Go to Step 6 | |
6 |
Does the scan tool indicate that the FTT is at the specified value? | 0 V | Go to Step 10 | Go to Step 7 |
7 | Test the signal circuit of the FTT sensor for an open circuit or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Test for an intermittent and for a poor connection at the FTT sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the G/H Van Service Manual. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | |
10 | Repair the low reference circuit of the FTT sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the G/H Van Service Manual. Did you find and complete the repair? | -- | Go to Step 13 | -- |
11 | 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 13 | -- |
12 | 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 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
