Circuit Description
The fuel tank is equipped with 2 fuel level sensors, one in each reservoir of the fuel tank. The engine control module (ECM) uses inputs from the fuel level sensors in order to calculate the total fuel remaining in both sides of the fuel tank. Fuel is transferred from the left side of the tank to the right side of the fuel tank in order to ensure all of the usable fuel volume is available. The fuel pump supplies a small amount of pressurized fuel to the siphon jet pump through the fuel feed pipe. The pressurized fuel creates a venturi action inside the siphon jet pump causing fuel to be drawn out of the left side of the fuel tank. Fuel is then transferred through the internal transfer tube to the right side of the fuel tank. The fuel level in the fuel tank will equalize during fuel pump operation, during re-fueling and when the fuel level is more than 50 percent. If the ECM detects a lack of expected signal variation from the fuel sensors during normal operation, DTC P2636 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2636 Fuel Transfer Pump Flow Insufficient
Conditions for Running the DTC
| • | The engine is running. |
| • | DTC P2636 runs continuously once the above conditions have been met. |
Conditions for Setting the DTC
| • | The engine control module (ECM) detects that the right side fuel level is 3.7 liters (1.0 gallons) more than the left side fuel level. |
| • | The above condition is present for more than 2 minutes. |
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center, if equipped, may display a message. |
Conditions for Clearing the DTC
| • | 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 non-emission related diagnostic. |
| • | Clear the DTC with a scan tool. |
Diagnostic Aids
The condition may only occur when the fuel level is half full or near empty. The fuel level sensor unit may need to be removed for further diagnosis. A fuel level sensor that has an intermittent condition causes this DTC to set.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if a condition current.
-
This step verifies possible component problems within the fuel tank.
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 DTC fail this ignition? | 3 minutes | Go to Step 4 | Go to Step 3 | |||||||||
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | |||||||||
4 |
Is the voltage at the specified value? | 0.0 V | Go to Step 5 | Go to Step 6 | ||||||||
5 |
Is the voltage at the specified value? | 0.0 V | Go to Step 8 | Go to Step 7 | ||||||||
6 | Test the signal circuit of the left fuel level sensor for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||||
7 | Test the low reference circuit of the left fuel level sensor for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||||
8 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||||||
9 | Test for an intermittent and for a poor connection at the left fuel level sensor. 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 13 | Go to Step 11 | ||||||||
10 | Test for an intermittent and for a poor connection at the ECM. 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 13 | Go to Step 12 | ||||||||
11 | Replace the left fuel level sensor. Refer to Primary Fuel Tank Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||
12 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
