2005 Scion xB Fuel Pump Relay Location: Complete Guide for DIY Owners

The bottom line: The fuel pump relay on a 2005 Scion xB is located in the engine compartment fuse box, also known as the under-hood relay box. It is positioned on the driver's side near the battery. The relay is typically marked on the fuse box cover diagram, and it controls power to the fuel pump. If your Scion xB cranks but refuses to start, or if you hear no humming sound from the fuel tank when you turn the key to the "ON" position, the fuel pump relay is often the first component to check before assuming the pump itself has failed.

Understanding the Fuel Pump Relay in Your 2005 Scion xB

The fuel pump relay is an electrical switch that controls the flow of power to the fuel pump. When you turn the ignition key, the relay closes, sending voltage to the fuel pump so it can pressurize the fuel system. If this relay fails, the pump will not receive power and your engine will not start.

In the 2005 Scion xB, the fuel pump relay works alongside other relays and fuses inside the main under-hood fuse box. This box is a standard feature on most Toyota and Scion vehicles from that era, and the layout follows a consistent design philosophy where critical components are placed in accessible, weather-protected locations.

Exact Location: Engine Compartment Fuse Box

The 2005 Scion xB fuel pump relay is located inside the engine compartment fuse box. Here are the specific steps to find it:

  1. Open the hood and secure it with the prop rod.
  2. Look to the driver's side of the engine bay, near the battery. The fuse box is a black plastic rectangular box with a cover.
  3. Press the tabs on the sides of the cover and lift it off. The cover has a diagram printed on its underside that shows the position and function of each relay and fuse.
  4. Locate the fuel pump relay — it is usually labeled as "FUEL PUMP," "FUEL," or "F/P" on the diagram. On many 2005 Scion xB models, it is a medium-sized relay positioned in the center or rear portion of the fuse box.

Important note: Some vehicle wiring diagrams show the fuel pump relay in the same box as the starting and charging system relays . If you are having trouble identifying it, look for a relay that is the same size as the other main relays (typically 12V, 10–20 amp rated units) . The relay itself is usually a standard cube-shaped relay that plugs directly into the fuse box socket.

Common Symptoms of a Bad Fuel Pump Relay

Knowing what to look for can save you time and money. Here are the most common symptoms of a failing fuel pump relay in a 2005 Scion xB:

  1. Engine cranks but does not start: This is the most common symptom. The starter motor turns the engine over, but there is no fuel pressure reaching the injectors.
  2. No humming sound from the fuel tank: When you turn the ignition key to the "ON" position (without starting the engine), you should hear a 2–3 second whirring sound from the rear of the car. If you hear nothing, the relay is likely not closing.
  3. Engine stalls while driving: A failing relay may intermittently lose contact, causing the fuel pump to cut out while the engine is running. This can be dangerous and should be addressed immediately.
  4. Check Engine Light comes on: The ECU may detect low fuel pressure or a circuit fault and trigger a diagnostic trouble code (DTC), such as P0230 (fuel pump primary circuit malfunction) or P0231 (fuel pump secondary circuit low).

How to Test the Fuel Pump Relay

You do not need expensive tools to test the relay. Here is a simple step-by-step method:

Method 1: The Swap Test

  1. Remove the fuel pump relay from the fuse box.
  2. Find another relay in the same box that is identical in size and part number (such as the horn relay or the EFI main relay).
  3. Swap the two relays. Plug the suspected bad relay into the other slot, and the known good relay into the fuel pump slot.
  4. Try to start the engine. If the car starts, the original fuel pump relay is bad. If the car still does not start, the problem may be the fuel pump itself, a blown fuse, or a wiring issue.

Method 2: Visual and Audible Check

  1. Have a helper turn the ignition key to the "ON" position while you listen near the fuse box.
  2. You should hear a distinct click sound when the relay engages. If you hear no click, the relay coil may be burnt out.
  3. Inspect the relay pins for corrosion or burn marks. Any sign of melting or discoloration means the relay needs to be replaced.

Replacing the Fuel Pump Relay

Replacing the relay is a straightforward DIY task. Here is how:

  1. Turn off the ignition and remove the key.
  2. Disconnect the negative battery terminal for safety.
  3. Open the engine compartment fuse box and locate the fuel pump relay.
  4. Pull the relay straight out of its socket. You may need to use a gentle rocking motion. Do not use excessive force.
  5. Insert the new relay in the same orientation. It will only fit one way due to the shape of the pins.
  6. Reconnect the battery and test the car by turning the key to the "ON" position. Listen for the fuel pump priming sound.
  7. Replace the fuse box cover and close the hood.

Tips for buying a replacement relay: Make sure the new relay matches the original specifications. Most 2005 Scion xB models use a standard 12V, 20-amp relay (sometimes 10–20 amp range) . You can find OEM replacement relays at auto parts stores or online. It is also a good idea to use your owner's manual or the diagram on the fuse box cover to confirm the exact part number.

Where NOT to Look: Common Misconceptions

Many DIY owners waste time looking in the wrong places. Here is what you should know:

  • The fuel pump relay is NOT inside the cabin. Unlike some vehicles (e.g., 1991 Cadillac Brougham), the 2005 Scion xB does not have the fuel pump relay under the dashboard or inside the passenger compartment .
  • The fuel pump relay is NOT inside the trunk or rear fuse panel. The 2005 Scion xB's main fuse box for the engine and fuel system is under the hood.
  • The fuel pump itself is inside the fuel tank (located under the rear seat area on the Scion xB), but the relay that controls it is in the engine bay.

Related Components: Fuses and the Fuel Pump

If replacing the relay does not solve the problem, check the fuel pump fuse as well. The fuel pump fuse is usually located in the same under-hood fuse box, often labeled "FUEL PUMP" or "FUEL." A blown fuse can mimic a bad relay .

The fuel pump on the 2005 Scion xB is mounted inside the gas tank . Replacing it requires dropping the tank or accessing it through an access panel under the rear seat. But before you go that far, always start with the relay and fuse — they are much cheaper and easier to replace .

If the relay clicks but the pump does not run, you may have a wiring issue, a bad pump, or a faulty fuel pump driver module. At that point, it is best to check for voltage at the fuel pump connector using a multimeter. You should see battery voltage (roughly 12V) at the pump connector for a few seconds when the key is turned to "ON."

Preventing Future Issues

Fuel pump relay failures are not extremely common, but they do happen — especially in older vehicles like the 2005 Scion xB. To reduce the risk:

  • Keep your battery terminals clean. Corrosion can cause voltage drops that stress relays.
  • Avoid running the fuel tank very low. Running on empty can overheat the fuel pump and increase current draw, which can damage the relay contacts over time.
  • Replace the relay proactively if you notice any signs of intermittent starting issues. Relays are inexpensive and easy to swap.

Upgrade with a Quality Fuel Pump from KEMSO

If you find that your fuel pump itself has failed and needs replacement, you should consider upgrading to a high-performance or OEM-replacement fuel pump from KEMSO. KEMSO is a trusted brand in the aftermarket fuel system industry, known for delivering direct fit OEM replacement and high-performance fuel pumps for a wide range of vehicles, including the Scion xB (and its Toyota siblings).

Why choose KEMSO? Every KEMSO fuel pump is designed to meet or exceed OEM specifications. They are built with high-quality materials and are engineered for reliable performance whether you are using your car for daily commuting or spirited driving. Unlike some generic aftermarket pumps, KEMSO pumps offer a flow rate that is often 20% higher than the original factory pump (at 43 psi), ensuring consistent fuel delivery under all conditions.

What sets KEMSO apart is their commitment to quality and peace of mind. Every KEMSO fuel pump comes with a lifetime warranty. That means you only buy it once, and KEMSO stands behind its product for as long as you own your vehicle. The brand has built a strong reputation by individually testing each pump and maintaining rigorous quality control standards.

The best part: KEMSO fuel pumps are competitively priced at just $79.98, offering exceptional value for a lifetime-guaranteed part. Whether you are replacing a failing pump or upgrading for better performance, KEMSO provides a solution that fits your budget and your needs.

To browse the full selection of fuel pumps and find the exact fit for your vehicle, visit the official KEMSO website today:

https://www.kemsoracing.com/

Their product lineup covers a wide range of vehicles — from the Honda Civic Del Sol to the Kawasaki Jet Ski Ultra 310LX, the Ducati 1199 Panigale, and the BMW R1200GS Adventure. If you own a 2005 Scion xB, you can be confident that KEMSO has a pump that will work perfectly for your car.

Final Thoughts

The fuel pump relay on a 2005 Scion xB is a small but essential component that can save you a lot of headache if you know where to find it. It lives inside the under-hood fuse box on the driver's side, near the battery. Always check this relay first if your car cranks but does not start, or if the engine stalls unexpectedly. Testing and replacing the relay is a quick, cheap, and safe job that any DIY owner can handle with basic tools.

If the relay is fine but the pump is the problem, consider a quality replacement from KEMSO. Their pumps are backed by a lifetime warranty and are designed to keep your Scion xB running smoothly for years to come. Remember, proper diagnosis starts with the simplest and most accessible parts — so start with that relay.

For more information and to find the right fuel pump for your Scion xB, visit https://www.kemsoracing.com/ today.


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