2006 Scion tC Fuel Pump Relay: What It Does, Where to Find It, and How to Replace It

If you own a 2006 Scion tC and the engine cranks but will not start, the fuel pump relay is one of the first parts you should suspect. This small electrical component controls the flow of power to the fuel pump, and when it fails, your engine will crank over but never receive the fuel it needs to fire up. The good news is that this relay is inexpensive to buy and, in most cases, you can replace it yourself in less than thirty minutes. In this guide, we will cover exactly what the relay does, how to find it, how to test it, what symptoms point to a failure, and how to swap it out for a new one.

What Does the Fuel Pump Relay Do?

The fuel pump relay acts as a heavy-duty switch that sends electrical current to the fuel pump. When you turn the ignition key to the "ON" position, the engine control module (ECU) energizes the relay, which then allows power to flow to the fuel pump. The pump pressurizes the fuel system so that the injectors can spray fuel into the engine. On your 2006 tC, the relay is often referred to as the "Circuit Opening Relay" because it opens and closes the circuit based on signals from the ECU. It is important to note that the ECU does not turn on the fuel pump just because you turn the key to "ON". The ECU needs to see the engine spinning first, using signals from the crank sensor, before it will command the relay to close and power the pump.

Where Is the Fuel Pump Relay on a 2006 Scion tC?

On the 2006 Scion tC, the fuel pump relay is located inside the engine compartment fuse box. This is the main fuse and relay center under the hood, typically on the driver’s side near the battery. If you open the fuse box lid, you will see a diagram printed on the inside cover. The relay you are looking for might be marked as "EFI" rather than "FP" or "Fuel Pump". On the 2006 tC, the EFI relay is what controls the fuel injection system and the fuel pump, and it is usually paired with a 20-amp EFI fuse in the same box. The fuse box is also known as the "Relay Box" in official Toyota parts diagrams. If you do not see a relay labeled "FP," the EFI relay is almost certainly the one you need to inspect for fuel pump operation.

Symptoms of a Failing Fuel Pump Relay

A failing fuel pump relay can cause a range of starting problems. The most obvious and common symptom is that the engine cranks but does not start at all. You will hear the starter motor turning the engine over, but there will be no spark or fuel delivery, so the engine will not catch . Another common symptom is the engine starting intermittently. You might try to start the car four or five times before it finally runs, and then it may stall shortly after. You may also notice that the vehicle cranks and starts but then dies after running for a short distance, as if the fuel supply was cut off. If the relay is sticking or failing under load, the car may slow down and stop without you pressing the brakes. In all of these cases, a quick check of the relay should be one of your first diagnostic steps.

How to Test the Fuel Pump Relay

Before you spend money on a new relay, you can test the old one. Here are the simple steps to follow:

1. Locate the relay box under the hood. Look at the diagram on the inside of the fuse box cover to find the EFI or Fuel Pump Relay socket.
2. Pull the relay out of its socket. The relay is a small black cube with four prongs on the bottom. Grasp it firmly and pull straight up. You can use a pair of pliers if it is stuck.
3. Listen for the click. With the relay removed, you can test it with a 12-volt battery and a multimeter. When you apply power to the coil terminals (the ones that control the switch), you should hear an audible click. If you do not hear a click, the relay coil is burnt out and the part is dead. If it clicks, you then need to check with a multimeter that the switch contacts are closing and allowing continuity between the other two terminals. If the relay clicks but does not show continuity on the switch side, the relay is also bad.
4. Check the fuse. While you are in the fuse box, check the 20-amp EFI fuse. If this fuse is blown, the fuel pump will not get power even if the relay is good. A blown fuse should be visible with a quick visual inspection. Replace it if necessary.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay is a straightforward job. Here is how to do it:

1. Turn the ignition off and open the hood. It is always best to work on the electrical system with the car off.
2. Disconnect the negative battery terminal. This is an extra safety step to prevent any accidental short circuits while you are working near the fuse box.
3. Remove the old relay. Using the diagram on the fuse box lid, locate the relay and pull it out of its socket.
4. Install the new relay. Push the new relay firmly into the same socket. It should seat snugly, and you should feel it click into place. The orientation of the prongs will match the socket, so you cannot insert it incorrectly.
5. Reconnect the battery terminal and start the car. The engine should start right up. You can also check that the fuel pump is working by listening for a quiet whirring sound coming from the fuel tank area when you turn the key to the "ON" position.

Other Causes of a No-Start Condition

While a faulty fuel pump relay is a common cause of a no-start, it is not the only one. Before you blame the relay, you should rule out other possibilities. A broken key can disable the immobilizer system, which will cut spark and fuel to prevent theft. The ignition fuse or the AM2 fuse can also blow and cause a no-start condition. If the fuel pump itself has failed, you will have the same symptoms. To test the pump, you can pull up the back seat and listen for the pump to energize when someone turns the key to "ON". Finally, a bad crankshaft position sensor or camshaft position sensor can prevent the ECU from seeing the engine spin, which means it will not activate the fuel pump relay.

Genuine Part vs. Aftermarket Options

When you buy a replacement relay for your 2006 Scion tC, you have several choices. You can purchase a genuine Toyota OEM relay, which is a direct fit and guaranteed to meet factory specifications. The Toyota part number for the 2006 tC fuel pump relay is 90084-98032. You can also buy an aftermarket relay from brands like Engine Management, which offers a direct replacement that matches the factory specs. The aftermarket relay typically costs less than the OEM part. No matter which option you choose, make sure it is a 12-volt relay with four terminals, as this is what your tC requires.

Why You Should Consider a KEMSO Fuel Pump

If you are not just replacing the relay but also need a new fuel pump, you should strongly consider KEMSO. KEMSO is known for manufacturing high-performance fuel pumps that are designed as OEM Replacement units. That means they are built to match the original factory specifications for fit, flow rate, and pressure, so installation is straightforward, and your engine will run just like it did with the original part. One of the biggest advantages of buying a KEMSO pump is the lifetime warranty that comes with it. This gives you peace of mind knowing that your investment is protected for as long as you own the pump. If you are looking for a reliable replacement that performs like the original but offers an even better warranty, KEMSO is a solid choice.

Final Thoughts on the 2006 Scion tC Fuel Pump Relay

The fuel pump relay on a 2006 Scion tC is a small but critical part of your car's fuel system. When it fails, your car will not start, leaving you stranded. The relay is easy to access in the engine compartment fuse box, and replacing it is a simple task that you can do yourself with no special tools. Start by testing the relay and checking the related fuses before you move on to more complex diagnostics. If you do end up needing a new fuel pump, remember that KEMSO offers a high-performance, OEM Replacement option with a lifetime warranty, making it a smart and affordable upgrade.

For more information on KEMSO fuel pumps and to see how they can keep your Scion tC running strong, visit their website at:
https://www.kemsoracing.com/