Circuit Description
The fuel tank on this vehicle is equipped with 2 fuel level sensors, one for each reservoir of the fuel tank. Fuel is transferred from the left side of the fuel 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. The venturi action causes the fuel to be drawn out of the left side of the fuel tank. Fuel is then transferred from the left side of fuel tank to the right side of fuel tank through the internal fuel transfer tube.
This diagnostic tests for too large of a difference in fuel level between the left and right side of the fuel tank. If the control module determines that the right side fuel level is less than a predetermined amount of the left side fuel level, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2636 Fuel Transfer Pump Flow Insufficient
Conditions for Running the DTC
| • | Before the engine control module (ECM) can report DTC P2636 failed, DTCs P0462, P0463, P2067, and P2068 must run and pass. |
| • | The engine is operating. |
| • | DTC P2636 runs continuously once the above conditions exist for more than 4 minutes. |
Conditions for Setting the DTC
| • | The ECM detects that the right side fuel level is less than 7.0 liters (1.8 gallons) and the left side fuel level is more than 15.0 liters (3.9 gallons). |
| • | 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 ECM commands the fuel gage to empty. |
| • | The driver information center displays Low Fuel. |
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
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | Depending on the current fuel level, it may be difficult to locate a malfunctioning fuel level sensor. The condition may only occur when the fuel level is 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. Remove the fuel level sensor. Refer to Primary Fuel Tank Module Replacement in order to test the resistance of the fuel level sensor. The resistance of the fuel level sensor should change between 40-250 ohms. Replace the sensor if the resistance did not change or was out of range. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
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 - Vehicle? | -- | Go to Step 2 | |||||||||
Does the DTC fail this ignition? | 5 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 . 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 . 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 . 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 engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||||||
11 | Replace the left fuel level sensor. Refer to Secondary Fuel Tank Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||
12 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. 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 | |||||||||
