Circuit Description
The fuel temperature sensor is a thermistor that controls the signal voltage to the PCM. When the fuel is cold, the sensor resistance is high, therefore the PCM will see high signal voltage. As the fuel warms, the sensor resistance becomes less and the voltage drops. The fuel temperature sensor is integrated with the optical sensor.
Conditions for Running the DTC
The engine has been operating for 8 minutes.
Conditions for Setting the DTC
| • | The fuel temperature is less than or equal to 18°C (64°F). |
| • | All disgnostic set conditions met for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL off after three consecutive trips without a fault condition. |
| • | A History DTC will clear after forty consecutive warm-up cycles, if this or any other emmision related diagnostic does not report any failures. |
| • | Use of a scan tool will clear the DTC codes. |
Diagnostic Aids
A scan tool reads fuel temperature in degrees centigrade. A failure to detect an increase in fuel temperature could be the result of a poor connection or an open in the signal circuit.
An intermittent may be caused by the following:
| • | Poor connections |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
This step determines if DTC P0183 is a hard failure or an intermittent condition.
-
This test simulates a DTC P0182. If the PCM recognizes the low signal voltage (high temp) the PCM and wiring are OK.
-
This test will determine if the signal circuit is open. There should be 5 volts at the sensor connector if measured with J 39200 DMM. This will determine if there is a wiring problem or a malfunctioning PCM.
-
This step determines if there is a short to voltage on the signal circuit. A short to voltage increases current flow through the sensor which overwhelms the sensor. This does not allow the sensor to pull down the circuit to the correct voltage and thus display the correct temperature.
-
After repairing the short to voltage, check the sensor for proper operation.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing any DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The control module's data is deleted once the Clear Info function is used. Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the Fuel Temp less than or equal to the specified value? | 18°C (64°F) | |||
Does the scan tool display fuel temperature greater than the specified value? | 105°C (221°F) | |||
Jumper the Fuel Temperature sensor signal circuit to a known good ground. Does the scan tool display a Fuel Temp greater than the specified value? | 105°C (221°F) | |||
5 | DTC is intermittent. If no other DTC(s) are stored, refer to Diagnostic Aids. If additional DTCs are stored, refer to those table(s) first. Are any other DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
6 |
Did you perform a repair? | -- | ||
7 |
Did you perform a repair? | -- | ||
8 |
Did you perform a repair? | -- | ||
With a J 39200 DMM set to the mA scale, measure the current across the fuel temperature signal and the sensor ground circuit at the sensor harness connector. Is the current less than the specified value? | 50 mA | |||
Repair the short to voltage on the fuel temperature signal circuit. Is the action complete? | -- | -- | ||
11 | Inspect the PCM connectors for proper connections and replace the terminals, if necessary. Refer to Wiring Repairs . Did you perform a repair? | -- | ||
12 |
Important: The new injection pump must be timed. Refer to Fuel Injection Pump Timing Adjustment . Replace the injection pump. Refer to Fuel Injection Pump Replacement Is the action complete? | -- | -- | |
13 |
Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Replace the PCM. Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate the diagnostic Passed? | -- | ||
15 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
