Fuel Pump Relay

This procedure replaces the fuel pump relay, which controls power to the electric fuel pump. The relay is located in the underhood fuse/relay box.

Warnings

Tools required

Parts

• Fuel pump relay × 1 — ACDelco D1788C or equivalent 4-pin micro relay

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition OFF and remove key from vehicle (or remove key fob from vehicle interior)
3. Allow engine to cool if recently operated to prevent burns from underhood components
4. Place fender cover over left front fender to protect paint
5. Open hood and secure with prop rod if equipped

Procedure

1. 1

   Disconnect battery negative terminal
   Using a 10mm socket, loosen the negative (-) battery terminal bolt. Remove the cable from the battery post and position it away from the terminal to prevent accidental reconnection. Wait 2 minutes to allow vehicle systems to power down completely.
   Torque spec

   Battery Terminal Bolts8 Nm (6 lb-ft)
2. 2

   Locate underhood fuse/relay box
   The underhood fuse/relay box is located on the driver's side of the engine compartment, near the battery. It is a black rectangular box with a hinged cover.
   ℹ️On some model years, there may be a secondary relay box. Verify you are accessing the correct box by checking the cover diagram.
3. 3

   Remove fuse box cover
   Release the cover latches by pressing down and outward on each side. Lift the cover off and set aside in a clean area. The relay diagram is printed on the underside of the cover.
   ⚠Do not lose the cover. It contains the critical relay and fuse identification diagram needed for future service.
4. 4

   Identify fuel pump relay location
   Refer to the diagram on the underside of the fuse box cover. The fuel pump relay is typically labeled 'FUEL PUMP' or 'FP RELAY' and is usually a standard micro relay (4-pin or 5-pin). Note the relay's orientation and pin configuration before removal.
   ⚠Multiple relays in the box may look identical. Ensure you identify the correct relay using the diagram. Removing the wrong relay may cause other system malfunctions.
5. 5

   Remove old fuel pump relay
   Grasp the relay firmly and pull straight up with steady, even pressure. Use needle-nose pliers or a relay puller if needed, gripping the relay body (not the terminals). Rock gently side-to-side while pulling if relay is tight in socket. Inspect the relay terminals for corrosion, burning, or damage.
   ⚠Do not twist or bend the relay during removal. Do not grip the relay by its electrical terminals as they may break off.
6. 6

   Inspect relay socket
   Examine the relay socket in the fuse box for corrosion, melted plastic, burned terminals, or loose contacts. Use a flashlight to inspect inside the socket. If damage is present, the entire fuse/relay box must be replaced—do not attempt this relay replacement. If socket appears clean and undamaged, proceed.
   ⚠️Burned, melted, or corroded relay sockets indicate an electrical fault that will damage a new relay. The underlying cause must be diagnosed and repaired before relay replacement.
7. 7

   Test new relay (optional but recommended)
   If you have a multimeter, verify the new relay functions correctly before installation. Apply 12V to the relay coil terminals and verify continuity across the switched terminals. Consult relay pinout diagram on relay body or packaging.
   ℹ️Testing the relay before installation can save diagnostic time if a defective replacement part was supplied.
8. 8

   Install new fuel pump relay
   Apply a small amount of dielectric grease to the relay terminals if desired (optional). Align the new relay with the socket, ensuring correct orientation by matching the relay tab or notch with the socket key. Press the relay straight down into the socket with firm, even pressure until it seats completely flush with the box surface.
   ⚠Ensure relay is oriented correctly. Installing a relay backward or in the wrong orientation can damage vehicle electrical systems or the relay itself.
9. 9

   Reinstall fuse box cover
   Position the fuse box cover over the box, aligning the hinge or mounting points. Press down firmly until all latches click into place. Verify the cover is fully seated and secure.
   ℹ️A properly installed cover protects relays and fuses from moisture and debris contamination.
10. 10

    Reconnect battery negative terminal
    Position the negative battery cable onto the negative battery post. Install the terminal bolt and tighten to specification using a torque wrench. Ensure connection is clean and tight.
    ⚠Over-torquing battery terminals can crack the battery case or damage terminals. Under-torquing can cause poor electrical contact and starting problems.
    Torque spec

    Battery Terminal Bolts8 Nm (6 lb-ft)

Reassembly

1. Verify all fuse box latches are engaged and cover is secure
2. Ensure no tools or parts are left in engine compartment
3. Remove fender cover

Verification

• Turn ignition to ON position (do not start engine). Listen for the fuel pump to run for 2-3 seconds, then stop. This primes the fuel system and confirms relay operation.
• Start the engine and verify it starts normally and runs smoothly without hesitation or stalling
• Check for any new warning lights on the instrument cluster
• Test drive the vehicle to confirm normal acceleration and no fuel delivery issues under load
• If engine does not start or fuel pump does not activate, recheck relay installation orientation and socket condition. Use a multimeter to verify relay is receiving power and ground signals.
• Verify radio presets, clock, and other electronics reset correctly after battery reconnection

Related trouble codes on this vehicle

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