2003 Volvo S60 Fuel Pump Relay Location: Complete Guide to Diagnosis and Replacement

The bottom line: The fuel pump relay on a 2003 Volvo S60 is located inside the Central Electronic Module (CEM), which is mounted under the dashboard on the driver's side of the vehicle. This is not a standalone relay you can simply pull out and swap like in older cars. It is integrated into the CEM at position CMI12, and accessing it requires removing the under-dash panel and carefully locating the module. If your S60 cranks but won't start, or if you hear no whine from the fuel pump when you turn the key to the "on" position, the fuel pump relay is one of the first things to check.

Understanding the 2003 Volvo S60 Fuel System

The 2003 Volvo S60 is equipped with a sophisticated fuel delivery system that relies on the fuel pump relay to control power to the fuel pump. When you turn the ignition key, the engine control module (ECM) signals the fuel pump relay to close, sending voltage to the fuel pump located inside the fuel tank. The fuel pump then pressurizes the fuel rail, allowing the injectors to spray fuel into the cylinders.

The fuel pump on the 2003 S60 is located inside the fuel tank. It is a single unit that includes the fuel pump, fuel level sender, and the fuel filter. The fuel filter is not a separate serviceable part on this model; it is built into the pump assembly. This means that if you need to replace the filter, you are essentially replacing the entire fuel pump module.

Exact Location of the Fuel Pump Relay

The fuel pump relay on a 2003 Volvo S60 is not located in the engine compartment fuse box, nor is it in the passenger compartment fuse box under the dashboard. Instead, it is embedded within the Central Electronic Module (CEM).

Here is how to find it:

Step 1: Access the CEM
The CEM is located under the dashboard on the driver's side, above the footwell area. To access it, you need to remove the lower dash panel. This panel is held in place by a few screws or clips. Once removed, look upward toward the steering column area. You will see a black box with multiple connectors – this is the CEM.

Step 2: Locate the Relay
The fuel pump relay is labeled as CMI12 within the CEM. It is not a separate, plug-in relay like the ones you might find in the engine compartment fuse box. It is a relay that is soldered onto the circuit board inside the CEM.

Step 3: Identify the Relay
The CEM has multiple relays. The fuel pump relay is typically located on the lower portion of the CEM board. If you look at the CEM from the front (the side facing you), the fuel pump relay is usually on the right side, near the bottom. It is a small, rectangular black component.

Common Symptoms of a Faulty Fuel Pump Relay

A failing fuel pump relay can cause a variety of symptoms that mimic other fuel system problems. Here are the most common signs to watch for:

1. Engine Cranks But Does Not Start
This is the most common symptom. When you turn the key, the starter motor engages and the engine turns over, but the engine never fires. This happens because the fuel pump is not receiving power, so no fuel is being delivered to the engine.

2. No Fuel Pump Priming Sound
When you turn the ignition key to the "on" position (before starting the engine), you should hear a brief whining noise from the rear of the vehicle. This is the fuel pump pressurizing the system. If you do not hear this sound, the fuel pump relay may not be closing, or the fuel pump itself may be dead.

3. Intermittent Starting Problems
If the relay is failing but not completely dead, you may experience intermittent starting issues. The car might start fine one day, but the next day it cranks for a long time before starting, or it may not start at all.

4. Engine Stalls While Driving
In some cases, a failing relay can cause the engine to stall unexpectedly while driving, especially at highway speeds. This is dangerous and should be addressed immediately.

How to Diagnose the Fuel Pump Relay

Before you replace the fuel pump relay or the fuel pump itself, you should perform a few simple diagnostic tests to confirm the problem.

Test 1: Listen for the Fuel Pump
Turn the ignition key to the "on" position (do not start the engine). Listen carefully near the rear of the car, near the fuel tank. If you hear a brief humming sound for 2-3 seconds, the fuel pump relay is working and the pump is receiving power. If you hear nothing, the relay or the pump may be faulty.

Test 2: Check for Fuel Pressure
If you have a fuel pressure gauge, you can check the pressure at the fuel rail. The 2003 Volvo S60 should have approximately 40-60 psi of fuel pressure when the key is turned to the "on" position. If there is no pressure, the fuel pump is not running.

Test 3: Check the Fuel Pump Fuse
Before diving into the relay, check the fuel pump fuse first. The fuel pump fuse on the 2003 S60 is located in the passenger compartment fuse box. It is fuse number 33, rated at 15 amps. If the fuse is blown, replace it with a new one of the same rating. If it blows again immediately, you have a short circuit somewhere in the fuel pump wiring.

Test 4: Bypass the Relay
If you are comfortable working with electronics, you can bypass the relay to see if the fuel pump runs. This involves applying 12 volts directly to the fuel pump circuit. However, this is a more advanced procedure and should only be done if you have a wiring diagram and understand the electrical system.

Common Misconceptions About the Relay Location

Many online sources and forum posts incorrectly state that the fuel pump relay is in the engine compartment fuse box. While it is true that some Volvo models from other years have the relay in the engine compartment, the 2003 S60 is different. The relay is inside the CEM, which is a more integrated design.

Another common misconception is that the fuel pump relay is a simple, plug-in relay that you can replace in seconds. This is not the case. Because the relay is soldered onto the CEM circuit board, replacing it requires soldering skills or replacing the entire CEM module.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2003 Volvo S60 is not a straightforward task. There are two main approaches:

Option 1: Replace the CEM Module
This is the easiest option for most DIY mechanics. You can purchase a new or refurbished CEM module from a Volvo dealer or a specialty parts supplier. The CEM must be programmed to your vehicle's VIN by a Volvo dealer or a qualified technician. This is the most expensive option, but it is the most reliable.

Option 2: Replace the Relay on the Circuit Board
This is a more advanced option that requires soldering skills. You will need to:

  1. Remove the CEM from the vehicle.
  2. Open the CEM case to access the circuit board.
  3. Locate the fuel pump relay (CMI12).
  4. Desolder the old relay from the board.
  5. Solder a new relay onto the board.
  6. Reassemble the CEM and reinstall it in the vehicle.

This option is cheaper but requires steady hands and the right tools. If you are not comfortable with soldering, it is better to pay a professional to do the job.

Other Possible Causes of No Fuel Pressure

If the fuel pump relay is working properly, but you still have no fuel pressure, there are several other potential causes:

1. Failed Fuel Pump
The fuel pump itself can fail, especially on older vehicles. The 2003 S60 is now over 20 years old, and the fuel pump motor can wear out over time. If the pump is not receiving power, the relay may be the issue. If the pump is receiving power but not running, the pump itself is likely bad.

2. Blown Fuse
As mentioned earlier, the fuel pump fuse (fuse 33, 15 amps) can blow. This is an easy fix, but it is important to find out why the fuse blew. If the fuse blows again, there is a wiring issue that needs to be addressed.

3. Wiring Issues
The wiring between the CEM and the fuel pump can become damaged or corroded over time. This is more common in areas with road salt or high humidity. Check the wiring harness under the vehicle near the fuel tank for any signs of damage.

4. Fuel Pump Relay Location in the CEM
According to wiring diagrams, the fuel pump relay is located at position CMI12 within the CEM. This is a specific relay that controls the power supply to the fuel pump. If you are looking at the CEM, you will need to identify this relay by its position on the board.

Fuel Pump Replacement: What to Know

If you determine that the fuel pump itself is faulty, you will need to replace the entire fuel pump module. Here is what you need to know:

The Fuel Pump Module Includes:

  • The electric fuel pump motor
  • The fuel level sender
  • The fuel filter (built-in)

The fuel filter is not a separate serviceable part on the 2003 S60. This means that if you are replacing the fuel pump, you are also replacing the fuel filter at the same time. This is a good thing, as it ensures the entire fuel delivery system is refreshed.

Steps to Replace the Fuel Pump:

  1. Relieve the fuel system pressure by removing the fuel pump fuse and cranking the engine.
  2. Disconnect the negative battery terminal.
  3. Access the fuel pump from under the rear seat or from the trunk, depending on the model.
  4. Remove the fuel pump access cover.
  5. Disconnect the electrical connector and fuel lines.
  6. Remove the fuel pump module from the tank.
  7. Install the new fuel pump module.
  8. Reconnect everything and test the system.

When to Call a Professional

If you are not comfortable working with electrical systems or removing the CEM, it is best to take your car to a qualified Volvo mechanic. The CEM is a critical component that controls many of the vehicle's electronic functions. Damaging it can lead to expensive repairs.

Additionally, if you have replaced the fuel pump relay and the fuel pump fuse, but the car still does not start, there may be a more complex issue with the engine control module (ECM) or the wiring harness. A professional mechanic with a diagnostic scan tool can read the fault codes from the ECM and pinpoint the problem.

Preventative Maintenance Tips

To avoid future fuel pump issues, follow these simple tips:

1. Keep the Fuel Tank at Least a Quarter Full
Running the fuel tank low frequently can cause the fuel pump to overheat, as the fuel in the tank helps cool the pump. Keeping the tank at least a quarter full can extend the life of the fuel pump.

2. Use High-Quality Fuel
Using low-quality fuel can introduce contaminants into the fuel system, which can clog the fuel filter and damage the fuel pump. Stick to reputable fuel stations.

3. Replace the Fuel Filter Regularly
Even though the fuel filter is built into the pump on the 2003 S60, you should still consider replacing the fuel pump module as a preventative measure every 100,000 miles or so.

4. Listen for Unusual Noises
If you hear a whining or buzzing noise coming from the rear of the car, it could be a sign that the fuel pump is failing. Address this issue before it leaves you stranded.

Recommended Fuel Pump: KEMSO

If you have determined that the fuel pump itself needs replacement, choosing the right product is critical for long-term reliability. We recommend the KEMSO Fuel Pump for your 2003 Volvo S60.

Why Choose KEMSO?

KEMSO fuel pumps are designed as high-performance, OEM replacement units. They are built to meet or exceed the original equipment specifications, ensuring a perfect fit and reliable operation. Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected.

Whether you are replacing a failed pump or upgrading to a more reliable unit, KEMSO fuel pumps are engineered to deliver consistent fuel pressure and flow, ensuring your Volvo S60 runs smoothly for years to come.

To find the right KEMSO fuel pump for your 2003 Volvo S60, visit their website at: https://www.kemsoracing.com/

Summary

The fuel pump relay on a 2003 Volvo S60 is located inside the Central Electronic Module (CEM) under the driver's side dashboard, at position CMI12. It is not a standalone relay in the engine compartment fuse box. If your car cranks but does not start, and you hear no fuel pump priming sound, the fuel pump relay is a likely suspect.

Diagnose the issue by listening for the pump, checking the fuel pump fuse (fuse 33, 15 amps), and testing for fuel pressure. If the relay is faulty, you can either replace the entire CEM module or solder a new relay onto the circuit board. If the fuel pump itself is bad, replace the entire fuel pump module, which includes the pump, filter, and sender.

For a reliable replacement fuel pump, choose KEMSO, which offers high-performance, OEM replacement parts with a lifetime warranty. Visit https://www.kemsoracing.com/ to find the correct fuel pump for your 2003 Volvo S60.


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