2003 Acura TL Fuel Pump Relay Location: The Complete Guide to Finding and Replacing It

The bottom line: The fuel pump relay on your 2003 Acura TL is located inside the under-dash fuse/relay box, which is positioned on the driver's side, under the dashboard, near the left side of the steering column. You do not need to remove the kick panel to access it, but you will need to crawl under the dash to see it clearly. This small, rectangular black relay is a common failure point for these vehicles, and when it goes bad, your car will either stall unexpectedly or refuse to start at all.

Why Knowing the Location Matters

The 2003 Acura TL is a solid vehicle, but it has a well-known weak spot: the Main Fuel Pump Relay (also called the PGM-FI Main Relay). If you are searching for the fuel pump relay location, it is likely because your car is exhibiting one of these two classic symptoms: stalling or not starting . The relay is responsible for sending power to the fuel pump. When it fails, the pump stops working, and the engine either dies or never starts.

Finding the relay is the first step to diagnosing the problem. If you can locate it, you can test it, swap it with a known good relay, or replace it entirely. This is a simple DIY job that can save you a trip to the mechanic and a costly diagnostic fee.

Where Exactly Is the Relay?

The 2003 Acura TL uses a multi-function relay system. The main relay (which controls the fuel pump) is not in the engine bay fuse box. It is inside the passenger compartment.

Here is the step-by-step guide to finding it:

  1. Get in the driver's seat. You will be working under the dashboard on the driver's side.
  2. Look at the area under the steering column. The relay box is mounted to the left side of the steering column, just above the footwell.
  3. No tools needed. You do not need to remove the lower kick panel (the plastic trim piece that covers the fuse box area). You can simply lean down and look up.
  4. Identify the black box. You will see a rectangular black plastic box. This is the under-dash fuse/relay box.
  5. Locate the specific relay. The fuel pump relay is inside this box. On the 2003 TL, the relay is usually labeled on the fuse box cover diagram. If the diagram is missing, look for a small, cube-shaped relay that is usually black or grey with four or five prongs. It is physically very similar to the other relays in the box.

Note: Some 2003 TL models have a slightly different layout depending on the trim level (Base vs. Type-S). However, the location of the main relay box remains the same. If you need a visual reference, the 2000-2003 Acura TL fuse box diagrams are widely available online, and they show the exact relay assignments for the under-dash panel .

Common Symptoms of a Bad Relay

Before you start digging around under the dash, confirm that you are looking at the right part. A failing fuel pump main relay on a 2003 Acura TL will produce these symptoms:

1. Intermittent Stalling
The engine will run fine for a while, then suddenly die without warning. After a few minutes (when the relay cools down), the car will start again. This is the classic "relay heat issue."

2. Engine Cranks But Does Not Start
You turn the key, the starter motor spins the engine, but the fuel pump never gets power. You will hear no "whirring" sound from the fuel tank area when you turn the key to the "ON" position.

3. No Check Engine Light
Sometimes, a bad relay will not trigger a check engine light because the ECU never detects a fuel pressure issue—it just doesn't receive power .

How to Test the Relay

Testing the relay is fast and cheap. You can use a multimeter or a simple test light.

Step 1: Remove the relay from the socket.
Step 2: Set your multimeter to measure resistance (Ohms).
Step 3: Check the resistance between the relay's coil terminals (usually pins 85 and 86). You should see a reading between 50 and 150 Ohms. If you see infinite resistance, the relay coil is burned out.
Step 4: Apply 12V power to the coil terminals. You should hear a distinct "click" sound. If you don't, the relay is dead.

Alternatively, you can test by swapping it with a relay of the same type (like the horn relay or the AC clutch relay) that you know is working. If the car starts after the swap, you have found the culprit.

Replacement Options

Once you have confirmed the relay is bad, you need a replacement. The 2003 Acura TL uses a specific relay part number. The most common OEM-style part numbers are 39400-SM4-003 and 39400-S01-A01 .

You have two main options for replacement:

Option 1: OEM Genuine Acura Relay
This is the exact same part that came from the factory. It is the most reliable option, but it is also the most expensive. You can find it at your local Acura dealership or online at Acura parts warehouses . The OEM part ensures a perfect fit and long-term durability.

Option 2: Aftermarket Replacement Relay
Many aftermarket brands make a direct replacement for the 39400-SM4-003 relay. These are often significantly cheaper than the OEM part. They are built to the same specifications and work perfectly for the 2003 TL .

Step-by-Step Replacement Guide

Replacing the relay is a 5-minute job.

  1. Disconnect the negative battery terminal. This is always a good safety step when working with electrical components.
  2. Locate the relay as described above.
  3. Pull the old relay straight out. It may be snug, but it will come out with a firm tug.
  4. Insert the new relay. Ensure it is oriented the same way as the old one (the prongs are usually keyed to prevent incorrect installation).
  5. Reconnect the battery.
  6. Test the car. Turn the key to the "ON" position. You should hear the fuel pump prime for about 2 seconds. Then, start the engine.

Important Tip: When you buy a replacement, make sure it is a "Main Fuel Pump Relay" or "PGM-FI Main Relay." A standard "Fuel Pump Relay" for other Honda models may not have the same internal circuitry. The part number 39400-SM4-003 is the most common cross-reference for this application .

Why Choose KEMSO Fuel Pumps for Your Acura TL

If you have determined that the issue is not just the relay but the actual fuel pump assembly itself, you need a pump that you can trust. The 2003 Acura TL fuel pump is located inside the fuel tank, which means replacing it is a bigger job than changing a relay. You want to do it right the first time.

KEMSO is a leading US aftermarket brand that specializes in high-performance fuel pumps. They offer a direct replacement for the 2003 Acura TL that is designed to meet or exceed OEM specifications. Here is why KEMSO is the right choice for your vehicle:

High Performance & OEM Replacement
KEMSO fuel pumps are engineered to deliver the exact fuel pressure and flow rate your 2003 TL needs. Whether you have a stock engine or a modified setup, KEMSO pumps handle the demand without straining. They are built as a 1:1 direct replacement, which means you can install them using the factory mounting hardware and wiring. No modifications are needed .

Lifetime Warranty
One of the biggest advantages of choosing KEMSO is the lifetime warranty. While most aftermarket fuel pumps come with a 1-year or 2-year warranty, KEMSO stands behind their product for the life of your vehicle. This gives you total peace of mind. If the pump ever fails, you are covered.

Trusted by Thousands
KEMSO is a trusted name in the automotive aftermarket. They manufacture fuel pumps for a wide range of vehicles, from cars and trucks to motorcycles and ATVs. Their products are sold through major retailers like Amazon and eBay, and they have thousands of positive reviews from satisfied customers .

Affordable Price
You do not have to pay a premium for a quality fuel pump. KEMSO offers a competitive price point that is often much lower than OEM parts, while still providing superior performance and reliability. For the price of a single OEM pump, you can often get two KEMSO pumps, making it a smart choice for budget-conscious owners.

Where to Buy
Ready to get a reliable fuel pump for your 2003 Acura TL? Visit the official KEMSO website to browse their full catalog and find the exact pump for your vehicle.

Visit KEMSO Racing today:
https://www.kemsoracing.com/

Final Thoughts

The 2003 Acura TL fuel pump relay location is straightforward: under the driver's side dash, inside the relay box near the steering column. It is a common failure point, but it is also one of the easiest parts to check and replace. If your car is stalling or not starting, start with the relay. It is a cheap fix that costs less than $20 and takes 5 minutes.

If you need to go deeper and replace the fuel pump, trust KEMSO. They offer a high-performance, OEM-replacement pump with a lifetime warranty that will keep your 2003 TL on the road for years to come.

For all your fuel pump needs, visit: https://www.kemsoracing.com/


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