Refer to Engine Controls Schematics
Fuel System
.
Circuit Description
The powertrain control module (PCM) uses the fuel level input in order to calculate the expected vapor pressures within the fuel system. These vapor pressures vary as the fuel level changes. The vapor pressure is critical in determining if the evaporative emissions system is operating properly. The PCM also uses the fuel level in order to determine if the fuel level is too high or too low to be able to accurately detect EVAP system malfunction.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The system voltage is between 10.0-18.0 volts. |
Conditions for Setting the DTC
The fuel level sensor should be more than 98 percent for more than 25 seconds.
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Faulty terminal connection--Inspect the harness connectors for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Faulty terminal-to-wire connection--Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. |
| • | A damaged harness--Inspect the wiring harness for damage. |
| If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. |
| • | Clean and secure the connections at the PCM and the engine grounds. |
If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain On Board Diagnostic (OBD) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
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This step tests for proper operation of the fuel level circuit in the high voltage range.
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This step tests for proper operation of the fuel level circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal is shorted to voltage.
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The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline information for PCM reprogramming and also refer to the CKP System Variation Learn Procedure for the Crankshaft Position System Variation Procedure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | |||
|
Important: If a 5-volt reference DTC sets, diagnosis this DTC first. Refer to DTC P1639 5 Volt Reference 2 Circuit .
Does the scan tool indicate that the Fuel Level parameter is more than the specified value? | 98% | Go to Diagnostic aids | ||
Does the scan tool indicate that the Fuel Level parameter is less than the specified value? | 3.5% | |||
4 | Test the fuel level signal circuit for a short to voltage, high resistance, or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
5 | Test the fuel level ground circuit for a short to voltage, high resistance, or an open. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
6 | Test for faulty connections at the fuel level sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
7 | Test the fuel level sensor circuit and fuel level ground circuit for faulty connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
8 | Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement . Is the action complete? | -- | -- | |
|
Important : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
10 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | System OK |
