Cooling Fan Relay

This procedure covers the diagnosis, removal, and replacement of the cooling fan relay on a 2024 Rivian EDV 500 dual motor electric delivery vehicle.

Warnings

Tools required

Parts

• Cooling fan relay × 1 — Use OEM specification
• Relay socket (if damaged) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn off vehicle completely using power button
3. Verify vehicle has been off for at least 5 minutes to allow high voltage system to discharge
4. Open frunk (front trunk) to access 12V battery and relay box
5. Connect diagnostic scanner and document any cooling system fault codes
6. Take photos of relay location and wiring before disassembly

Procedure

1. 1

   Disconnect 12V battery
   Locate the 12V auxiliary battery in the frunk. Remove the T30 Torx fasteners securing the battery cover. Disconnect the negative terminal first using a 10mm socket, then disconnect the positive terminal. Secure terminals away from battery posts.
2. 2

   Access the power distribution module
   The cooling fan relays are located in the power distribution module (PDM) in the frunk near the 12V battery. Remove the T20 Torx fasteners securing the PDM cover. Carefully lift the cover off, noting any clips or retaining tabs.
3. 3

   Identify the cooling fan relay
   Locate the cooling fan relay using the diagram on the underside of the PDM cover or in the vehicle service manual. The EDV 500 typically has multiple cooling circuits; identify whether you need the battery cooling fan relay, motor cooling fan relay, or auxiliary cooling fan relay based on diagnostic codes.
4. 4

   Test the suspected relay
   Before removal, use a multimeter to check for voltage at the relay control terminals. With the 12V battery reconnected temporarily, have an assistant activate the cooling system via diagnostic software. Verify the relay receives switching voltage (approximately 12V). Disconnect battery again before proceeding.
5. 5

   Remove the cooling fan relay
   Press down on the relay tab or locking mechanism and pull the relay straight up from the socket. Do not twist or rock the relay as this may damage the socket pins. Inspect the relay terminals for corrosion, burning, or damage.
6. 6

   Inspect relay socket and wiring
   Examine the relay socket for signs of overheating, melted plastic, corroded pins, or pushed-back terminals. Check for loose or damaged wiring at the back of the socket. If socket damage is present, the entire socket assembly must be replaced, which may require additional PDM disassembly.
7. 7

   Test the old relay
   Using a multimeter set to continuity mode, test the relay coil resistance between the control terminals (typically 80-120 ohms for a standard automotive relay). Apply 12V to the coil terminals using a bench power supply and verify the relay clicks and shows continuity across the load terminals. A failed relay will not click or show continuity.
8. 8

   Clean relay socket contacts
   Spray electrical contact cleaner into the relay socket and use compressed air to remove debris. Inspect each pin for proper tension. If pins are loose or corroded beyond cleaning, socket replacement is required.
9. 9

   Prepare new relay for installation
   Verify the new relay matches the specifications of the original (same amperage rating, terminal configuration, and pin layout). Apply a thin coat of dielectric grease to the relay terminals to prevent corrosion. Do not apply grease inside the socket.
10. 10

    Install new cooling fan relay
    Align the relay with the socket, ensuring correct orientation by matching the key tab. Press the relay firmly into the socket until it clicks and seats fully. Verify the relay is secure by gently attempting to remove it; it should not pull out without pressing the release tab.
11. 11

    Reinstall PDM cover
    Position the PDM cover back onto the module, ensuring all clips engage properly. Install the T20 Torx fasteners and tighten until snug. Do not overtighten plastic-mounted fasteners.
12. 12

    Reconnect 12V battery
    Reconnect the positive terminal first, then the negative terminal using a 10mm socket. Ensure connections are tight and secure. Install the battery cover and secure with T30 Torx fasteners.
13. 13

    Perform system test
    Connect the diagnostic scanner and power on the vehicle. Use the diagnostic software to activate the cooling fan system and verify the relay operates correctly. Listen for relay clicking and fan operation. Monitor coolant temperatures and fan activation thresholds.

Reassembly

1. Verify all PDM covers and fasteners are properly secured
2. Ensure no tools or parts are left in the frunk area
3. Confirm 12V battery terminals are tight and corrosion-free
4. Double-check that all diagnostic connectors are removed

Verification

• Clear all cooling system fault codes using diagnostic software
• Start vehicle and allow it to run through a complete cooling cycle
• Monitor live data to confirm fan relay activates at proper temperature thresholds
• Verify cooling fans cycle on and off appropriately for both battery and motor cooling systems
• Test drive vehicle and confirm no cooling system warnings appear on instrument cluster
• Perform a final diagnostic scan to ensure no new fault codes are present

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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