Circuit Description
The secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the primary fuel pump. The secondary fuel pump relay supply voltage is received from the primary fuel pump relay when the primary fuel pump is energized. This DTC sets when the powertrain control module (PCM) commands the secondary fuel pump ON and a predetermined change in both the front and rear fuel level sensors does not occur.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2636 Fuel Transfer Pump Flow Insufficient
Conditions for Running the DTC
| • | DTCs P0461, P0462, P0463, P2066, P2067, P2068 are not set. |
| • | The vehicle speed is 0 km/h (0 mph). |
| • | The engine has been idling for more than 2 minutes and 20 seconds. |
| • | The primary fuel level is less than 60 L (15.8 gal). |
| • | The secondary fuel level is more than 3 L (2.6 gal). |
Conditions for Setting the DTC
The PCM does not detect a change of 4 L (1.06 gal), in both the primary and the secondary fuel level sensors, with the secondary pump commanded ON for 120 seconds.
Action Taken When the DTC Sets
| • | The PCM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM 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. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step tests the supply voltage circuit of the secondary fuel pump relay. The test lamp should illuminate as the primary fuel pump is commanded ON.
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This step verifies the secondary fuel pump operation. Listen for an audible sound as the secondary fuel pump relay harness connector is jumpered.
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This step verifies that there is adequate fuel in the rear fuel tank. The rear fuel tank sensor voltage must be above 1 volt in order to continue.
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This step tests the secondary fuel pumps ability to transfer fuel. The rear fuel level sensor voltage should decrease while the secondary fuel pump is ON.
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This step tests for a short to ground on the control circuit of the secondary fuel pump relay. If the test lamp illuminates, a short to ground is indicated.
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This step tests for a short to voltage on the control circuit of the secondary fuel pump relay. If the test lamp illuminates, a short to voltage is indicated.
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This step verifies the secondary fuel pump relay operation. An audible click should be heard as the secondary fuel pump relay control circuit is grounded. The secondary fuel pump should turn ON as the fuel pump relay control circuit is grounded.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||
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Important: The fuel level must be between 25-50 percent to perform this diagnostic procedure. If the fuel level is not within this range, misdiagnosis will occur.
Does the test lamp illuminate when the fuel pump relay is commanded ON? | -- | Go to Step 3 | Go to Step 22 | |||||
3 | Probe the ignition voltage circuit of the secondary fuel pump relay, switch side, with a test lamp connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 12 | ||||
Connect a 15-amp fused jumper wire between the ignition 1 voltage and secondary fuel pump supply voltage circuit of the secondary fuel pump relay harness connector. Does the secondary fuel pump turn ON? | -- | Go to Step 5 | Go to Step 16 | |||||
Is the rear fuel level sensor voltage above the specified value? | 1 V | Go to Step 7 | Go to Step 6 | |||||
6 | Add the specified amount of fuel to the fuel tank. Did you complete the action? | 19 L (5 gal) | Go to Step 7 | -- | ||||
Does the rear fuel level sensor voltage decrease as the secondary fuel pump is operating? | -- | Go to Step 8 | Go to Step 18 | |||||
Does the test lamp illuminate? | -- | Go to Step 23 | Go to Step 9 | |||||
Probe the secondary fuel pump relay control circuit with a test lamp connected to a good ground. Does the test lamp illuminate? | -- | Go to Step 27 | Go to Step 10 | |||||
Does the secondary fuel pump turn ON when the fuel pump relay control terminal is grounded? | -- | Go to Step 11 | Go to Step 19 | |||||
11 | Test the secondary fuel pump relay control circuit for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 21 | ||||
12 | Inspect the PCM 1 fuse. Is the PCM 1 fuse open? | -- | Go to Step 13 | Go to Step 25 | ||||
13 | Test the ignition 1 voltage circuit of the secondary fuel pump relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 14 | ||||
14 | Test the voltage supply circuit of the secondary fuel pump for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 15 | ||||
15 |
Is the fuse open? | -- | Go to Step 29 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
16 |
Does the test lamp illuminate? | -- | Go to Step 17 | Go to Step 26 | ||||
17 | Probe the ground circuit of the secondary fuel pump with a test lamp connected to B+. Does the test lamp illuminate? | -- | Go to Step 20 | Go to Step 24 | ||||
18 | Inspect the fuel line between the primary and secondary fuel tanks for a restriction. Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 29 | ||||
19 | Test for an intermittent and for a poor connection at the harness connector of the secondary fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 28 | ||||
20 | Test for an intermittent and for a poor connection at the harness connector of the secondary fuel pump. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 29 | ||||
21 | Test for an intermittent and for a poor connection at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 30 | ||||
22 | Repair the open supply voltage circuit of the secondary fuel pump relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
23 | Repair the short to ground in the control circuit of the secondary fuel pump relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
24 | Repair the open ground circuit of the secondary fuel pump. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
25 | Repair the open ignition voltage circuit of the secondary fuel pump relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
26 | Repair the open supply voltage circuit of the secondary fuel pump. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
27 | Repair the short to voltage on the control circuit of the secondary fuel pump relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 31 | -- | ||||
28 | Replace the secondary fuel pump relay. Did you complete the replacement? | -- | Go to Step 31 | -- | ||||
29 | Replace the rear fuel sender assembly. Refer to Fuel Sender Assembly Replacement . Did you complete the replacement? | -- | Go to Step 31 | -- | ||||
30 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 31 | -- | ||||
31 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 32 | ||||
32 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
