Circuit Description
The fuel tank temperature (FTT) sensor is a variable resistor that measures the temperature of the fuel in the CNG fuel tank. The PCM supplies a 5 volt reference circuit and a signal circuit to the FTT sensor. This DTC sets when the FTT signal voltage is below the normal operating range of the sensor.
Conditions for Running the DTC
| • | DTCs P0112, or P0113 are not set. |
| • | The intake air temperature is more than -10°C (14°F). |
Conditions for Setting the DTC
| • | The fuel tank temperature sensor voltage is less than 0.06 volt. |
| • | The condition exists for more than 3 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 . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that a condition exists.
-
This step determines if a circuit condition is the cause of the DTC. The scan tool should display near 5 volts when the circuits are jumpered together.
-
This step test the 5 volt reference circuit of the FTT sensor. The DMM should display 5 volts if the circuit is OK.
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) |
Does the scan tool indicate that the FTT is less than the specified value? | 0.06 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 |
Does the scan tool indicate that the FTT sensor voltage is more than the specified value? | 4.8 V | Go to Step 8 | Go to Step 5 | |
Measure the voltage from the 5 volt reference of the FTT sensor wit a DMM. Refer to Measuring Voltage in Wiring Systems in the J Platform Service Manual. Does the DMM display a voltage near the specified value? | 5 V | Go to Step 6 | Go to Step 7 | |
6 | Test the signal circuit of the FTT sensor for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
7 | Test the 5 volt reference circuit of the FTT sensor for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the FTT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the J Platform Service Manual. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 |
10 | Replace the FTT sensor. The FTT sensor is not serviceable separately from the HPL. Refer to High Pressure Lock-Off Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
11 | Replace the PCM. Refer to Powertrain Control Module Replacement in the J Platform Service Manual. Did you complete the replacement? | -- | Go to Step 8 | -- |
12 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 |
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
