Circuit Description
The Fuel Tank Pressure sensor is mounted to the sending unit at the top of the fuel tank. The Fuel Tank Pressure sensor measures the pressure changes within the EVAP system. The Fuel Tank Pressure sensor has a 5.0 volt reference, a ground and a signal circuit.
The Fuel Tank Pressure sensor contains a diaphragm which changes the resistance based on the pressure. When the EVAP system pressure is low (during the purge) the sensor output voltage is low. When the system pressure is high, the sensor output voltage is high.
When the ECM senses the Fuel Tank Pressure sensor signal voltage outside the normal operating range of the sensor, this DTC will set.
Conditions for Running the DTC
Part 1:
Test continuously.
Part 2:
| • | The engine is at idle. |
| • | The ECT is at start less than 33°C (91°F). |
| • | The engine is running between 2 to 10 seconds. |
Conditions for Setting the DTC
Part 1:
| • | The tank pressure is greater than .27 kPa (1.1 in H2O). |
| • | The above condition met for at least 5 seconds |
OR
| • | The tank pressure is less than -.27 kPa (-1.1 in H2O). |
| • | The above condition met for at least 5 seconds. |
Part 2:
| • | The tank pressure is greater than 1.0 kPa (0.4 in H2O). |
| • | The above condition met for at least 3 seconds. |
Action Taken When the DTC Sets
The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes. |
| • | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. |
| • | The ECM battery voltage is interrupted. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.
Check for the following conditions:
| • | Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Control Module Diagnosis for the proper procedure. |
| • | Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc. |
| • | Damaged harness. Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault. |
If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or connections, the component may be damaged.
Refer to Symptoms for the Intermittents.
Test Description
The number(s) below refer to the step number(s) on the Diagnostic Table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System check? | -- | ||
2 |
Is the voltage within the specified range? | 2.2 to 2.8 V | ||
3 |
Important: Before continuing with the diagnosis, zero the EVAP Pressure and Vacuum gauges on EVAP pressure/purge cart J 41413 (refer to the tool operating instructions).
Is the voltage within the specified range? | 3.74 kPa (15 in. H20) 3.3 - 3.9 V | ||
4 |
Is the Fuel Tank Pressure Volts affected by moving the harness or connectors? | -- | ||
Is this DTC set? | -- | Refer to Diagnostic Aids | ||
6 |
Is the voltage within the specified range? | 4.7-5.3 V | ||
7 |
Is there any voltage present? | -- | ||
8 | Check the harness for continuity of the Fuel Tank Pressure sensor signal circuit with the DVM J 33431-C . Is continuity indicated? | -- | ||
9 | Check the harness for continuity between the Fuel Tank Pressure sensor signal circuit and battery ground with the DVM J 39200 . Is continuity indicated? | -- | ||
10 | Measure the voltage from the Fuel Tank Pressure sensor 5 volt reference circuit in the Fuel Tank Pressure sensor harness connector to battery ground with the DVM J 39200 . Is the voltage within the specified range? | 4.7-5.3 V | ||
11 |
Is there any voltage present? | -- | ||
12 | Check the harness for continuity of the Fuel Tank Pressure sensor 5 volt reference circuit with the DVM J 39200 . Is continuity indicated? | -- | ||
13 | Use the DVM J 39200 in order to check the harness for continuity between the Fuel Tank Pressure sensor 5 volt reference circuit and battery ground. Is continuity indicated? | -- | ||
14 |
Is the resistance within the specified range? | 0-5 ohms | ||
15 |
Is continuity indicated? | -- | ||
16 |
Does the scan tool indicate the specified voltage? | 0 V | ||
17 | Repair the harness/connections as necessary. Refer to Symptoms Is the action complete? | -- | -- | |
18 | Repair the short to voltage in the 5 volt reference circuit. Is the action complete? | -- | -- | |
19 | Repair the open/high resistance in the 5 volt reference circuit. Is the action complete? | -- | -- | |
20 | Repair the short to ground in the 5 volt reference circuit. Is the action complete? | -- | -- | |
21 | Repair the signal circuit that is shorted to voltage. Is the action complete? | -- | -- | |
22 | Repair the open/high resistance in the signal circuit. Is the action complete? | -- | -- | |
23 | Repair the short to ground in the signal circuit. Is the action complete? | -- | -- | |
24 | Repair the open/high resistance in the ground circuit. Is the action complete? | -- | -- | |
25 | Check for a poor connection or poor terminal tension at the Fuel Tank Pressure sensor harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis . Was a problem found and corrected? | -- | ||
26 | Replace the Fuel Tank Pressure sensor. Is the action complete? | -- | -- | |
27 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis . Was a problem found and corrected? | -- | ||
28 |
Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming . Is the action complete? | -- | -- | |
29 |
Is this DTC set? | -- | ||
30 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | The System is OK |
