2005 Toyota Highlander Fuel Pump Relay Location: Where It Is and How to Fix a No-Start

The fuel pump relay on a 2005 Toyota Highlander is located in the engine compartment fuse box, commonly called the engine room relay block, which sits on the left side of the engine bay near the battery. It is typically labeled as the "Circuit Opening" relay, and it controls power to the fuel pump. If your Highlander cranks but will not start, a faulty relay is one of the first things to check. This guide shows you exactly where to look, how to test the relay, and what to do if it needs replacing.

Why the Fuel Pump Relay Matters

The fuel pump relay acts as an electrical switch. When you turn the ignition key to the ON position, the engine control module sends a low-current signal to the relay. That signal energizes an electromagnet inside the relay, which closes a set of contacts. This allows full battery voltage to flow to the fuel pump, pressurizing the fuel system so the engine can start. Once the engine is running, the relay stays closed to keep fuel flowing. If the relay fails, the fuel pump gets no power, and the engine will crank but not fire. This part is sometimes called the circuit opening relay because it controls circuits for the fuel pump and other fuel system components. On many Toyota models, including the 2005 Highlander, the relay is found in the engine compartment fuse and relay box. It is a small, cube-shaped component that is easy to remove and replace with basic hand tools.

Where to Find the Relay on a 2005 Toyota Highlander

Open the hood and look for the main fuse box. On the 2005 Highlander, this is a black plastic box located on the left side of the engine compartment, near the battery and fender. Remove the cover by pressing the release tabs and lifting it off. On the underside of the cover, there is a diagram that shows the location and label of every fuse and relay. Look for a relay labeled "C/OPN" (circuit opening) or "EFI." The circuit opening relay is the fuel pump relay for your Highlander. It is usually grouped with other relays, often near the EFI relay and other engine control relays. If the diagram on the cover is faded or missing, you can still identify the relay by its position. It is typically one of the standard-size relays with four or five prongs on the bottom.

Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay often causes problems that are easy to notice. The most common symptom is an engine that cranks normally but will not start. You may also notice that you do not hear the fuel pump prime when you turn the key to the ON position. The fuel pump normally makes a brief humming or buzzing sound for about two seconds from the rear of the vehicle, near the fuel tank. If this sound is missing, the pump is not receiving power, and the relay is a likely suspect. Other symptoms include intermittent stalling while driving, especially when the vehicle is warm, and a loss of power under load. These problems happen because the relay contacts are worn or corroded and fail to deliver steady power. Keep in mind that a bad fuel pump itself can cause similar symptoms, so testing the relay first is a smart way to narrow down the problem.

How to Test the Fuel Pump Relay

Before you replace anything, it is worth taking a few minutes to test the relay. Here is a simple step-by-step approach:

  1. Turn the ignition to the ON position but do not crank the engine. Listen for the fuel pump prime sound from the rear of the car. If you hear nothing, the pump is not getting power.
  2. Check the related fuses. Look at the fuse box diagram to find the fuse that protects the fuel pump circuit. On the 2005 Highlander, the EFI No.1 fuse (20A) powers the fuel pump. If that fuse is blown, replace it and try again.
  3. Swap the relay. Find another relay in the same fuse box that has the same part number and pin configuration. The horn relay or the headlight relay often works. Pull out the suspected fuel pump relay, push in the known-good relay, and turn the key to ON. If the pump primes, your original relay is bad.
  4. Listen for a click. With the ignition ON, you should feel and hear a distinct click from the relay as it energizes. If there is no click, the relay may not be receiving the signal from the engine control module, or the relay coil is burned out.

If you are comfortable using a multimeter, you can also test for continuity and voltage at the relay socket. But for most owners, the swap test is the easiest and fastest way to confirm the relay is the problem.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2005 Highlander is a straightforward job that takes only a few minutes. You will need a new relay with the correct part number. For the 2005 Highlander, the OEM relay part numbers include 90080-87010, 90987-02027, and 90987-T2001. Aftermarket options are also available, but it is safest to match the OEM specifications.

Follow these steps:

  1. Disconnect the negative battery cable. This prevents accidental shorts and protects the electrical system.
  2. Open the engine compartment fuse box and locate the circuit opening relay.
  3. Pull the old relay straight out. It may require a firm tug, but it should come out without much effort. If it is stuck, use a pair of needle-nose pliers or a relay puller.
  4. Push the new relay firmly into the same socket. Make sure it seats all the way down.
  5. Reconnect the battery cable.
  6. Turn the key to ON and listen for the fuel pump prime. If you hear the pump, the installation is successful.

The whole process usually takes less than 15 minutes, even for a first-time DIYer. The relay itself is inexpensive, typically costing between $20 and $50 for an OEM part.

What Else Could Cause a No-Start Condition

If the relay checks out and the fuel pump is priming, the problem may lie elsewhere. Other common causes of a no-start on a 2005 Highlander include a faulty crank position sensor, a clogged fuel filter, a failing fuel pump, or an engine control module issue. On some models, water intrusion from a leaking sunroof can damage electrical components near the driver side kick panel, including relays. If you have had a sunroof leak, it is worth inspecting the wiring and relay sockets for corrosion. The security system can also prevent starting in rare cases. Check that the security light is not flashing when you turn the key to ON, because that indicates an immobilizer issue.

A Practical Suggestion for a Reliable Fuel Pump

If you find that your fuel pump itself is failing, not just the relay, choosing a high-quality replacement is important. KEMSO offers a line of fuel pumps designed as direct OEM replacements. Their pumps are built for high performance and come with a lifetime warranty, which gives you peace of mind that the part will last. Whether you drive a car, truck, or SUV, KEMSO has a wide selection of fuel pumps for many popular models. You can browse their full catalog and order directly from their website: https://www.kemsoracing.com/

Final Thoughts

Knowing the 2005 Toyota Highlander fuel pump relay location can save you time and money. It sits in the engine compartment fuse box on the left side of the engine bay, labeled as the circuit opening relay. When your Highlander cranks but will not start, start with the simple checks: listen for the pump prime, inspect the fuses, and swap the relay with a known-good one. Most of the time, a bad relay is the culprit, and replacing it takes only a few minutes. If the relay is fine, move on to checking the fuel pump, fuses, and sensors. And if a new fuel pump is needed, consider a reliable aftermarket option like KEMSO, available at https://www.kemsoracing.com/


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