Circuit Description
The fuel temperature (FT) sensor is a thermistor. The engine control module (ECM) supplies the FT sensor a reference voltage of 5 volts on the signal circuit and also provides a low reference circuit to the sensor. When the FT sensor is cold, the resistance is high. The FT sensor signal voltage remains near the supplied voltage cold and decreases the signal voltage as the sensor warms. The control module monitors the FT sensor signal circuit in order to calculate the temperature of the fuel entering the engine.
Conditions for Running the DTC
| • | DTCs P0112, P0113, P0182, P0183, or P1683 are not set. |
| • | Engine must be turned OFF for 10 hours or longer. |
| • | Start-up intake air temperature (IAT) is more than 10°C (50°F). |
Conditions for Setting the DTC
The FT and the IAT are more than 10°C (18°F) of each other at start-up.
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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if the IAT sensor reading is reading within a normal range. If the reading is outside of the specification, the IAT sensor may have a fault in the sensor or circuit.
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This step determines if the fault is present at the time of diagnosis.
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Reprogram the replacement ECM. Refer to the latest techline information for ECM programming.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the scan tool indicate a temperature near ambient temperature within the specified range? | +-10°C 18° F | Go to Step 3 | Go to Step 4 | |
Does the DTC fail this ignition? | Go to Step 6 | Go to Intermittent Conditions | ||
4 |
Does the voltage measure near the specified value? | 5 V | Go to Step 5 | Go to Step 9 |
5 |
Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 11 |
6 |
Does the voltage measure near the specified value? | 5 V | Go to Step 8 | Go to Step 9 |
7 | Connect a 3-amp fused jumper wire between the fuel temperature sensor signal circuit and ground. Is the temperature more than the specified value? | 140°C (285°F) | Go to Step 8 | Go to Step 10 |
8 |
Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 11 |
9 |
Did you perform a repair? | -- | Go to Step 16 | Go to Step 12 |
10 | Repair the high resistance in the fuel temperature sensor signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 16 | Go to Step 12 |
11 | Repair the open or the high resistance in the sensor low reference circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 16 | Go to Step 13 |
12 | Inspect the ECM connector terminals for spreading or poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 |
Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | |
14 | Replace the MAF sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
15 | Replace the FT sensor. Refer to Fuel Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- |
16 |
Does the DTC run and pass? | -- | Go to Step 17 | Go to Step 2 |
17 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
