Important: If you were not referred to this test from another diagnostic, DO NOT perform this procedure.
The secondary fuel pump is located inside the secondary fuel tank. The fuel pump is powered by a secondary fuel pump relay. Fuel is transferred from the secondary fuel tank to the primary 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. The fuel sender and balance pump control module supplies ground to the secondary fuel pump relay which energizes the secondary fuel pump.
| • | The primary fuel level sensor resistance goes below 86 ohms and is 9 ohms less than the secondary fuel level sensor. |
| • | The primary fuel pump is commanded ON. |
| • | The primary fuel level sensor is 86 ohms or greater. |
| • | Open fuel level sensors or wiring. |
| • | The primary fuel level sensor is 8 ohms greater than the secondary fuel level sensor. |
The numbers below refer to the step numbers on the diagnostic table.
This step verifies the fuel level circuits.
This step verifies the secondary fuel pump operation.
This step verifies if voltage is being supplied to the fuel pump.
This step verifies if ignition voltage is being supplied to the relay.
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 fuel gage indicate over the full mark? | -- | Go to Step 10 | Go to Step 3 | |
Does the secondary fuel pump turn ON? | -- | Go to Step 6 | Go to Step 4 | |
Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 5 | |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 16 | |
6 |
Is fuel flow present? | -- | Go to Step 23 | Go to Step 12 |
7 |
Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 17 |
8 |
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 19 |
9 |
Does the secondary fuel pump turn ON? | -- | Go to Step 13 | Go to Step 18 |
10 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 16 |
11 | Probe the ground circuit of the fuel balance control module at the module harness connector with a test lamp connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 14 | Go to Step 20 |
12 |
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 22 |
13 | Test for an intermittent and for a poor connection at the fuel sender and balance pump control relay. 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 24 | Go to Step 21 |
14 | Test for an intermittent and for a poor connection at the fuel sender and balance pump control module. 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 24 | Go to Step 23 |
15 | Test for an intermittent and a poor connection at the secondary fuel pump. 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 24 | Go to Step 22 |
16 | Repair the open Ignition 3 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
17 | Repair the open fuel pump supply voltage circuit of the secondary fuel pump relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
18 | Repair the open fuel pump supply voltage circuit of the secondary fuel pump. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
19 | Repair the open fuel pump relay control circuit of the fuel sender and balance pump control relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
20 | Repair the open ground circuit of the fuel sender and balance pump control module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- |
21 | Replace the fuel sender and balance pump control relay. Refer to Relay Replacement in Wiring Systems. Did you complete the replacement? | -- | Go to Step 24 | -- |
22 | Replace the secondary fuel pump assembly. Refer to Fuel Pump Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
23 | Replace the Fuel Sender and Balance Pump control Module. Refer to Fuel Sender and Balance Pump Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- |
24 |
Did you correct the condition? | -- | Go to Step 25 | Go to Step 2 |
25 | Observe the Capture Info with a scan tool. Are there any DTCs that are not diagnosed? | -- | System OK | |