Relay - Generic

This procedure covers the removal and replacement of a generic relay in the 2009 Aston Martin DB9. Relay locations vary by system, but the procedure addresses common relay box access points and removal techniques.

Warnings

Tools required

Parts

• Relay (specific to failed system) × 1 — Use OEM specification - varies by circuit

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Turn ignition to OFF position and remove key.
3. Allow engine to cool if working in engine bay (minimum 30 minutes after shutdown).
4. Identify the specific relay to be replaced using fault code data, wiring diagram, or relay box legend.
5. Disconnect negative battery terminal to prevent electrical shorts during relay removal.

Procedure

1. 1

   Disconnect battery negative terminal
   Open the boot and locate the battery, which on the DB9 is mounted in the trunk (typically under a trim/carpet panel). Using the appropriate socket, loosen the negative terminal bolt and remove the cable from the battery post. Secure the cable away from the terminal to prevent accidental reconnection. Note: Open the boot and locate the battery, which is mounted in the trunk (typically on the driver-side rear) on the DB9 — it is NOT in the engine bay. Using the appropriate socket, loosen the negative terminal bolt and remove the cable from the battery post. Secure the cable away from the terminal to prevent accidental reconnection. Note: Open the boot and locate the battery (mounted in the luggage compartment, typically on the driver side). Using a 10mm socket, loosen the negative terminal bolt and remove the cable from the battery post. Secure the cable away from the terminal to prevent accidental reconnection.
   Torque spec

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

   Access relay location - Engine bay
   If relay is located in the engine bay fuse/relay box: Locate the relay box cover (consult the OEM wiring diagram for its exact side/position in the engine bay) and release the retaining clips by pressing inward while lifting. Some boxes may have a single Torx fastener at the center. Remove cover and set aside. The relay diagram is typically printed on the underside of the cover or inside the box.
   ℹ️Engine bay relay box is most common location for powertrain-related relays (fuel pump, ignition, cooling fans).
3. 3

   Access relay location - Passenger footwell
   If relay is located in the passenger footwell junction box: Remove the lower trim panel on the passenger side by carefully pulling outward at the bottom edge to release the press-fit clips. The junction box is mounted to the bulkhead behind the trim. Locate the access cover and release the clips or remove the Torx fasteners securing it.
   ⚠Trim clips are fragile. Apply steady, even pressure to avoid breaking mounting points.
4. 4

   Access relay location - Trunk distribution box
   If relay is located in the trunk: Open the trunk and locate the side-mounted distribution box (typically driver side). Remove the carpet-covered access panel by releasing the press-fit fasteners or Velcro strips. The relay box cover will have clips or Torx fasteners securing it.
   ℹ️Trunk distribution boxes typically house body control relays (lighting, windows, central locking).
5. 5

   Identify target relay
   Using the relay diagram on the box cover or in the owner's manual, identify the exact relay position. Cross-reference with the fault code or symptom diagnosis. Note the relay amperage rating and color code if visible. Relays in the DB9 are commonly mini ISO or standard ISO format; verify the exact pin configuration against the removed relay and wiring diagram before ordering a replacement.
   ⚠Removing the wrong relay may cause additional fault codes or disable safety systems. Verify position carefully before proceeding.
6. 6

   Remove failed relay
   Grasp the relay body firmly and pull straight upward with steady pressure. If the relay is difficult to grip, use a relay removal tool or needle-nose pliers on the relay body (not the terminals). Rock the relay gently side-to-side while pulling if it resists removal. Inspect the relay socket for corrosion, burn marks, or damaged terminals.
   ⚠Do not use excessive force or pry against adjacent relays. Damaged socket terminals will require entire fuse box replacement.
7. 7

   Inspect relay and socket
   Examine the removed relay for physical damage: melted plastic, burned terminals, or loose internal components (rattling sound when shaken). Check the socket terminals for discoloration, corrosion, or spreading. If socket damage is present, cleaning or socket repair may be required before installing new relay. Use a multimeter to test relay coil resistance if available; compare the reading against the specification for the specific relay part number rather than a generic value, as acceptable coil resistance varies by relay. Note: Use a multimeter to test relay coil resistance if available, comparing against the specification for the specific relay part number (coil resistance varies by relay type; consult the OEM data for the exact value). Note: Use a multimeter to test relay coil resistance if available, comparing the reading against the specification for that specific relay (automotive 12V relay coils commonly range from roughly 60 to 160 ohms depending on type).
8. 8

   Install new relay
   Verify the new relay matches the original: same part number, amperage rating, pin configuration, and physical dimensions. Align the relay pins with the socket, ensuring correct orientation (notch or tab on relay body matches socket). Press the relay firmly into the socket until it seats completely and sits flush with surrounding relays. The relay should click into place and not rock when touched.
   ⚠Incorrect relay orientation or mismatched specifications can cause component damage or fire. Double-check part number and pin alignment.
9. 9

   Reinstall relay box covers
   Replace the relay box cover, ensuring the seal is properly seated. Secure with clips or Torx fasteners as applicable. If accessing passenger footwell or trunk locations, reinstall access panels and trim pieces by aligning clips and pressing firmly until seated.
10. 10

    Reconnect battery and initialize
    Reconnect the negative battery terminal and tighten the terminal clamp bolt to specification. Ensure cable connection is clean and tight. Insert the key/Emotion Control Unit (verify which ignition system this specific 2009 DB9 uses — early cars use a conventional key with a starter button, later cars use the glass-key ECU) and power up the vehicle (ignition on, engine off) per the DB9 start procedure, then verify warning lights illuminate normally on the instrument cluster. The vehicle may require a brief initialization period for systems to stabilize. Note: Reconnect the negative battery terminal (located in the boot) and tighten the 10mm bolt to specification. Ensure the cable connection is clean and tight.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. All trim panels and covers must be fully seated with clips engaged to prevent rattles and water intrusion.
2. Verify relay box covers are properly sealed to prevent moisture contamination of electrical components.
3. Reprogram radio presets, clock, and driver preference settings as needed after battery reconnection.

Verification

• Start the engine and verify the system controlled by the replaced relay functions normally (e.g., fuel pump primes, cooling fans cycle, lights operate).
• Clear any stored fault codes using a diagnostic scanner and verify no new codes are generated.
• Perform a test drive to confirm symptom resolution under normal operating conditions.
• Check for proper relay operation by cycling the affected system multiple times (if applicable).
• Verify no electrical burning smell or unusual heat from the relay location after 10-15 minutes of operation.

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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