Main Relay

This procedure covers the replacement of the main relay (EFI relay) in the engine compartment relay box, which controls power to the fuel injection system and other critical components.

Warnings

Tools required

Parts

• Main relay (EFI relay) × 1 — 90987-02028 or equivalent
• Dielectric grease × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition off and remove key
3. Allow engine to cool if recently operated
4. Open hood and secure with prop rod

Procedure

1. 1

   Disconnect battery negative terminal
   Using a 10mm socket, loosen the negative battery terminal bolt. Remove the cable and secure it away from the battery post to prevent accidental reconnection during the procedure.
   Torque spec

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

   Locate the engine compartment relay box
   The main relay box is located on the driver's side of the engine compartment, mounted to the inner fender near the strut tower. It is a black rectangular box with multiple relays and fuses.
3. 3

   Remove relay box cover
   Release the cover tabs by pressing and lifting upward. The cover may have a diagram showing relay positions. Set the cover aside in a clean location to reference the relay layout.
4. 4

   Identify the main relay
   Locate the main relay (also called EFI relay) using the diagram on the relay box cover or underhood label. It is typically labeled 'EFI MAIN' or 'EFI' and is usually a larger relay compared to others in the box. Position is generally in the center or front section of the relay box.
5. 5

   Remove the main relay
   Grip the relay firmly and pull straight upward with steady even pressure. Do not rock side to side as this can damage the socket terminals. If relay is difficult to remove, gently wiggle while pulling upward. Inspect the relay socket for corrosion, debris, or damaged terminals.
6. 6

   Inspect relay socket and terminals
   Examine the relay socket for signs of heat damage (melting, discoloration), corrosion, or bent pins. If corrosion is present, clean with electrical contact cleaner and allow to dry completely. Bent pins should be carefully straightened with needle nose pliers. Check the old relay terminals for burn marks or corrosion.
7. 7

   Install new main relay
   Apply a small amount of dielectric grease to the relay terminals to prevent corrosion. Align the new relay with the socket, ensuring correct orientation by matching the tab or notch on the relay base with the socket. Press firmly and evenly downward until the relay is fully seated and flush with surrounding relays. You should feel a positive click when properly installed.
8. 8

   Reinstall relay box cover
   Position the cover over the relay box, ensuring all edges are properly aligned. Press down firmly on all corners and edges until all tabs click into place. Verify the cover is fully seated with no gaps.
9. 9

   Reconnect battery negative terminal
   Clean the battery terminal and post with a wire brush if corrosion is present. Place the negative cable onto the negative battery post and hand-tighten the terminal bolt. Torque the battery terminal bolt to specification using a torque wrench.
   ⚠Do not overtighten battery terminal bolts as this can crack the terminal or strip threads
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Ensure relay box cover is fully secured with all clips engaged
2. Verify no tools or parts were left in engine compartment
3. Close hood and ensure it latches properly

Verification

• Turn ignition to ON position (do not start) and listen for fuel pump priming (2-second hum from rear of vehicle)
• Check that all dashboard warning lights illuminate normally during key-on cycle
• Start the engine and verify it starts normally without extended cranking
• Allow engine to idle and confirm smooth operation with no warning lights
• Test turn signals, headlights, and other electrical accessories to ensure proper system function
• If vehicle fails to start or fuel pump does not prime, recheck relay installation and orientation

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