This procedure covers the replacement of the main power distribution relay in the underhood fuse box, which controls power distribution to multiple vehicle systems.

Warnings

Tools required

Parts

• Main power distribution relay × 1 — Use OEM specification or Motorcraft DY-861

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition to OFF position and remove key
3. Open hood and secure with prop rod
4. Locate the underhood fuse and relay box on driver side fenderwell
5. Take photo of fuse box cover relay diagram for reference

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 secure it away from the terminal to prevent accidental contact. Wait 2 minutes for system capacitor discharge.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
2. 2

   Remove fuse box cover
   Release the locking tabs on the sides of the underhood fuse box cover. Lift the cover straight up to remove. The relay diagram is printed on the underside of the cover for relay identification.
3. 3

   Identify main relay location
   Locate the main power distribution relay in the fuse box. On 2011-2014 F-150 models, this is typically labeled as relay R1 or R2 in the front row of the relay box. It is a larger relay, typically gray or black in color. Verify against the diagram on the fuse box cover.
4. 4

   Remove main relay
   Grasp the relay firmly and pull straight up with steady pressure. If the relay is difficult to remove, use a relay puller tool or carefully insert a flathead screwdriver under each side of the relay base to gently pry upward. Do not rock the relay side to side as this may damage the socket terminals.
   ⚠Inspect relay socket terminals for corrosion, discoloration, or damage before installing new relay
5. 5

   Inspect relay socket
   Examine the relay socket in the fuse box for any signs of heat damage, melted plastic, corrosion, or bent terminals. If terminals are corroded, clean with electrical contact cleaner and a small wire brush. If socket shows heat damage or melted terminals, the entire fuse box may require replacement.
   ⚠Socket heat damage indicates underlying electrical problem - investigate before installing new relay
6. 6

   Prepare new relay
   Remove new relay from packaging. Verify the relay part number matches the original. Optionally apply a thin coat of dielectric grease to the relay blade terminals to prevent corrosion and ensure good electrical contact.
7. 7

   Install new relay
   Align the new relay with the socket, ensuring the relay orientation matches the socket keying. Press the relay firmly into the socket until it seats completely and is flush with surrounding relays. You should feel a positive click as the terminals engage.
8. 8

   Reinstall fuse box cover
   Position the fuse box cover over the fuse box and press down firmly until all locking tabs click into place. Ensure the cover is fully seated and secure.
9. 9

   Reconnect battery
   Clean the battery terminal post and cable clamp with a wire brush if corrosion is present. Place the negative cable onto the negative battery post and tighten the terminal bolt to specification. Ensure connection is secure but do not overtighten.
   ⚠Overtightening battery terminals can crack the terminal clamp or damage the battery post
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Verify all fuse box cover tabs are fully engaged and cover is secure
2. Ensure no tools or parts are left in engine compartment
3. Close hood securely

Verification

• Turn ignition to ON position (do not start engine) and verify dash lights illuminate normally
• Check for any warning lights or fault messages on instrument cluster
• Start engine and verify it cranks and starts normally
• Test electrical accessories (lights, radio, power windows) to confirm proper power distribution
• If original problem was no-start condition, verify vehicle starts consistently multiple times
• Allow engine to idle for 2-3 minutes and verify no electrical issues occur

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