This procedure covers the replacement of a relay in the engine compartment or cab fuse/relay boxes on a 2015-2020 Ford F-150 with the 5.0L Coyote V8 engine.

Warnings

Tools required

Parts

• Relay (specific to circuit being repaired) × 1 — Use OEM specification based on relay position
• Dielectric grease × 1 — Optional - for terminal protection

Preparation

1. Park vehicle on level ground and set parking brake
2. Turn ignition to OFF position and remove key
3. Locate the relay to be replaced using owner's manual or fuse box diagram (typically found on fuse box cover)
4. If replacing high-current relay (fuel pump, starter, cooling fan), disconnect negative battery terminal and wait 2 minutes for system discharge
5. Open the appropriate fuse/relay box cover by releasing the retaining tabs or clips

Procedure

1. 1

   Access the relay location
   For engine compartment boxes: Release the cover clips and lift the fuse box cover straight up. For interior fuse panel: Pull the panel cover toward you to release the clips. Locate the specific relay position using the diagram on the cover or in the owner's manual. Note the relay amperage rating and part number if visible.
2. 2

   Inspect existing relay and terminals
   Visually inspect the relay for signs of overheating, melted plastic, or corrosion. Check the relay socket terminals for discoloration, burning, or corrosion. If terminals are damaged, the socket may require replacement or professional repair.
3. 3

   Remove the faulty relay
   Grasp the relay body firmly and pull straight up with steady pressure. Some relays have a tab that must be lifted before removal. For relays that are difficult to access, use needle-nose pliers to grip the relay body (not the terminals). Rock gently side-to-side while pulling if relay is tight in socket.
   ⚠Do not pull on relay terminals or wires - grasp only the relay body to avoid damaging socket pins
4. 4

   Clean the relay socket
   Inspect socket terminals for corrosion or debris. Use electrical contact cleaner and a small brush if needed to clean socket pins. Ensure all terminals are straight and not bent. Verify no foreign objects or moisture are present in the socket.
5. 5

   Verify new relay specifications
   Compare the new relay to the old relay, ensuring identical part number or equivalent specification. Verify amperage rating, terminal configuration, and physical dimensions match. Check that relay type (standard, mini, or micro) is correct for the socket.
   ⚠Installing incorrect relay amperage rating can cause circuit damage or fire hazard. Always match OEM specifications
6. 6

   Install new relay
   Apply a small amount of dielectric grease to relay terminals if desired for corrosion protection (optional). Align relay terminals with socket pins, ensuring correct orientation. Press relay firmly into socket until fully seated and flush with surrounding relays. You should feel a positive click or resistance when relay is properly installed.
7. 7

   Reinstall fuse box covers
   Ensure no tools or debris remain in fuse box. Position cover and press down firmly to engage all retaining clips. Verify cover is fully seated and secure. If removed, reconnect battery negative terminal and tighten to specification.
   ℹ️Battery terminal bolt specification is critical - overtightening can damage battery post or terminal
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Ensure all fuse box covers are properly secured with no gaps
2. Verify battery terminals are clean and properly tightened if disconnected
3. Clear any diagnostic trouble codes if relay replacement was due to electrical fault

Verification

• Turn ignition to ON position (engine off) and verify no warning lights indicate electrical faults related to replaced relay circuit
• Start engine and verify the system controlled by the relay operates correctly (cooling fan cycles, fuel pump primes, etc.)
• For intermittent issues, test drive vehicle under conditions that previously caused failure
• Use multimeter to verify proper voltage at relay socket if system still does not function (should see battery voltage on power supply terminal with ignition on)
• Check for proper relay clicking sound when circuit is activated if audible

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