2008 Scion tC Fuel Pump Relay Location: Find It Fast and Fix It Right

The bottom line up front: On a 2008 Scion tC, the fuel pump relay is located inside the engine bay fuse and relay box, which sits near the battery on the passenger side of the vehicle. If your tC cranks but won't start, this relay is one of the first things you should check before assuming the fuel pump itself has failed.

The 2008 Scion tC comes with a 2.4-liter four-cylinder engine (2AZ-FE) and has been a popular compact coupe since its introduction. It's a reliable car, but like any vehicle with age on it, electrical components like relays can wear out. In this guide, we will walk you through exactly where the fuel pump relay lives, how to test it, what symptoms point to a bad relay, and how much you should expect to pay for a replacement.

Where Exactly Is the Fuel Pump Relay on a 2008 Scion tC?

The fuel pump relay on the 2008 Scion tC is housed in the main fuse and relay box located in the engine compartment. More specifically, you will find this black box positioned near the battery on the passenger side of the engine bay.

To access it:

  1. Pop the hood and secure it with the prop rod.
  2. Look toward the passenger side of the engine bay, near the strut tower and battery area.
  3. Locate the black plastic box with a removable cover. This is the engine bay fuse and relay box.
  4. Remove the cover by pressing the locking tabs and lifting it straight up.
  5. Look at the underside of the cover – the diagram printed there will show you which relay position is labeled for the fuel pump. In most Scion and Toyota products of this era, the fuel pump relay is clearly marked on this diagram.

In some vehicles, the fuel pump relay is located under the dashboard near the steering column, but for the 2008 Scion tC, it is almost universally found in the engine bay fuse box.

What Does the Fuel Pump Relay Do?

The fuel pump relay is an electrical switch that controls the flow of power to the fuel pump. It is activated by the engine control module (ECM) when you turn the ignition key to the "ON" position.

When the relay receives the low-current signal from the ECM, it closes its internal contacts, allowing high current from the battery to flow to the fuel pump. This pressurizes the fuel system so the engine can start and run.

Essentially, the fuel pump relay acts like a middleman between the battery and the fuel pump, ensuring the pump gets the power it needs without overloading the vehicle's wiring or the ECM itself.

Symptoms of a Failing Fuel Pump Relay on a 2008 Scion tC

If the fuel pump relay is failing or has failed completely, you may notice one or more of the following symptoms:

  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 because the pump is not receiving power.

  2. Intermittent starting issues. The car may start fine sometimes, and other times it refuses to start. This often indicates a relay with worn internal contacts that make poor connection.

  3. Engine stalls while driving. If the relay fails while you are on the road, the fuel pump will stop running, and the engine will die. The car may restart after a few minutes once the relay cools down.

  4. No fuel pump prime sound. When you turn the key to the "ON" position (without cranking), you should hear a faint whirring sound from the rear of the car for about two seconds. This is the fuel pump priming. If you hear nothing, the relay may not be sending power to the pump.

  5. Check Engine Light illuminates. The ECM may detect a fuel delivery issue and set a trouble code related to low fuel pressure or a fuel pump circuit fault.

Important note: These symptoms can also be caused by a faulty fuel pump, a clogged fuel filter, or a wiring issue. That is why it is critical to test the relay first before spending money on a new fuel pump.

How to Test the Fuel Pump Relay on a 2008 Scion tC

Before you go out and buy a new relay, you can test the current one with a digital multimeter and a couple of jumper wires. Here is a step-by-step process:

  1. Remove the relay from the fuse box as described above. The relay is a small black cube with four or five metal prongs on the bottom.

  2. Identify the terminals. Look at the diagram on the relay housing or the fuse box cover. Typically, there are two small control terminals (the coil) and two larger power terminals. On Toyota relays of this era, the terminals are often labeled "85," "86," "30," and "87." Terminals 85 and 86 are the coil, while 30 and 87 are the power contacts.

  3. Test the coil resistance. Set your multimeter to ohms and touch the probes to terminals 85 and 86. You should see a resistance reading somewhere between 50 and 120 ohms. If the meter reads infinite or zero, the coil is burned out or shorted, and the relay needs to be replaced.

  4. Test the contacts. Connect a 12-volt power source (like a battery) to the coil terminals using a couple of jumper wires. Then, set the multimeter to continuity mode and touch the probes to terminals 30 and 87. The meter should beep or show near-zero resistance, indicating the contacts are closed. If there is no continuity, the relay is defective.

  5. Swap test. The easiest method is to simply swap the suspected fuel pump relay with a relay of the same type from another position in the fuse box (like the horn relay). If the car starts with the swapped relay, the original relay is bad.

Replacement Cost for a 2008 Scion tC Fuel Pump Relay

If your tests confirm the relay is bad, you will need to replace it. The good news is that a fuel pump relay is an inexpensive part.

Parts cost: A genuine OEM relay (part number 90084-98032) for the 2008 Scion tC is priced around $55.59 online and typically retails for about $77.38 at the dealership. Aftermarket relays can be found for as little as $10 to $20.

Labor cost: If you choose to have a mechanic handle the replacement, expect to pay between $95 and $150 for labor, depending on your area. The total estimate for a fuel pump relay replacement on a Scion tC averages around $122, with parts accounting for about $27 and labor for $95.

DIY savings: Since the relay is right in the engine bay and requires only basic hand tools, most owners can replace it in under 15 minutes themselves. That means your total cost can be as low as the price of the relay alone.

Step-by-Step: How to Replace the Fuel Pump Relay on a 2008 Scion tC

Replacing the fuel pump relay is one of the easiest repairs you can do on this car. Here is the full process:

  1. Turn off the ignition and remove the key.
  2. Disconnect the negative battery terminal to prevent any electrical shorts while you work.
  3. Open the hood and locate the fuse and relay box near the passenger side battery.
  4. Remove the fuse box cover by pressing the tabs and lifting it off. Set it aside.
  5. Locate the fuel pump relay using the label map on the cover or this guide.
  6. Pull the relay straight up out of its socket. Gently wiggle it side to side if it seems stuck.
  7. Compare the new relay with the old one to make sure they are identical (same pin configuration and amperage rating).
  8. Push the new relay firmly into the socket until it clicks into place.
  9. Reinstall the fuse box cover and snap it shut.
  10. Reconnect the negative battery terminal.
  11. Turn the key to the "ON" position and listen for the fuel pump prime sound. Then, start the engine.

What to Do If a New Relay Doesn't Fix the Problem

If you have installed a brand new relay and the car still will not start, the issue is likely not the relay. Move on to these checks:

  1. Check the fuel pump fuse. Locate the 15-amp fuse labeled for the fuel pump in the fuse box and test it with a multimeter. A blown fuse will also prevent the pump from running.

  2. Listen again for the fuel pump. If the relay clicks but there is no prime sound, the fuel pump itself may be dead. On the 2008 Scion tC, the fuel pump is inside the fuel tank and requires more involved work to replace.

  3. Check for fuel pressure. Use a fuel pressure gauge on the fuel rail test port. If pressure is below spec, verify whether the pump is receiving voltage and ground while cranking.

  4. Inspect the circuit opening relay. Some Toyota vehicles use a separate "circuit opening relay" that controls the fuel pump in certain conditions. While the tC generally uses a standard fuel pump relay, it is worth checking your specific fuse box diagram to see if additional relays control the pump.

  5. Scan for diagnostic trouble codes. Connect an OBD-II scanner to see if the ECM has stored codes related to fuel delivery, like P0087 (fuel rail pressure too low) or P0230 (fuel pump primary circuit malfunction).

Preventive Maintenance Tips for the Fuel Pump System

A fuel pump relay typically lasts well over 100,000 miles, but there are a few things you can do to extend its life and avoid getting stranded:

  1. Keep the fuel tank above a quarter full. Running the tank low repeatedly can overheat the fuel pump, which increases the electrical load on the relay.

  2. Replace the relay proactively. If you are already in the fuse box for any reason and your car has over 150,000 miles, consider replacing the relay while you are in there. It is cheap insurance.

  3. Check for corroded contacts. Pull the relay out and inspect the socket terminals for any greenish corrosion. If present, clean them with electrical contact cleaner before reinstalling.

  4. Do not use generic relays of unknown quality. Always choose a relay rated for the correct amperage. Using a lower-rated relay can cause it to overheat and fail prematurely.

  5. Address starting issues early. If you notice intermittent no-start conditions, do not ignore them. A failing relay can damage the fuel pump by providing inconsistent power.

Frequently Asked Questions About the 2008 Scion tC Fuel Pump Relay

Q: Can I drive with a bad fuel pump relay?

A: No. If the relay fails completely, the fuel pump stops running, and the engine will shut off or refuse to start. You will be stranded.

Q: How long does a fuel pump relay last?

A: There is no guaranteed lifespan, but many last 10 to 15 years or more. The relay in your 2008 tC has already outlived the typical service life of many vehicles, so if you are having issues, replacement is a wise step.

Q: Is it worth paying a mechanic to replace the relay?

A: Given how simple it is to access and replace, most owners can do it in minutes. The money you save is better spent elsewhere.

Q: Will a bad relay damage the fuel pump?

A: Yes, potentially. If the relay provides intermittent power, the fuel pump may run erratically, which can overheat the pump motor and shorten its lifespan.

Q: Is the fuel pump relay the same as the fuel pump fuse?

A: No. A fuse protects the circuit from overcurrent, while a relay is a switch that controls whether power is sent to the pump. You need both working correctly.

Summary

The 2008 Scion tC fuel pump relay is located in the engine bay fuse and relay box on the passenger side near the battery. It is a small black cube labeled clearly on the fuse box cover diagram. If your car cranks but will not start, check this relay first before assuming the fuel pump is dead. Testing takes less than five minutes with a multimeter, and replacing the relay costs between $50 and $100 in parts, or around $122 total if you hire a professional.

Do not forget that the fuel pump relay is just one part of the fuel delivery system. If the relay checks out, move on to checking the fuse, the fuel pump itself, and the wiring, and scan for trouble codes. Tackling these checks systematically will save you time and money and get your tC back on the road quickly.

Why Choose KEMSO for Your Fuel Pump Replacement

If your fuel pump does turn out to be the culprit, you want a replacement that is built to last and performs like the factory original. KEMSO fuel pumps are an excellent choice for any vehicle, including the 2008 Scion tC.

KEMSO specializes in high-performance fuel pumps that are designed as direct OEM replacements. That means each pump is engineered to match the exact fit, flow rate, and electrical specifications of the original pump in your vehicle. You do not need to modify anything or worry about compatibility issues.

Here is what sets KEMSO apart:

  • High Performance: KEMSO fuel pumps are built to deliver consistent, reliable fuel pressure under all driving conditions, from daily commuting to aggressive driving.
  • OEM Replacement Quality: Every KEMSO pump is manufactured to meet or exceed original equipment specifications, so you can install it with confidence.
  • Lifetime Warranty: KEMSO stands behind their products with a lifetime warranty, giving you total peace of mind. If your KEMSO fuel pump ever fails, you are covered.

Whether you own a Scion tC, a BMW motorcycle, a Kawasaki Jet Ski, or any other vehicle, KEMSO has a solution. Their lineup includes hundreds of applications for cars, trucks, motorcycles, and powersport vehicles, all backed by the same commitment to quality.

Visit the KEMSO website today to browse their full catalog of fuel pumps and find the right one for your needs:

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