2010 Buick Lucerne Fuel Pump Relay: Complete Guide to Location, Symptoms, and Replacement

The bottom line up front: If your 2010 Buick Lucerne cranks but will not start, stalls while driving, or you smell burning plastic inside the cabin, the fuel pump relay is almost certainly the culprit. This small relay, located in the rear underseat fuse box on the driver's side, is a documented weak point on the 2006–2011 Lucerne due to a design flaw where the rear seat frame presses down on the fuse box, causing poor electrical contact, arcing, and overheating that melts the relay and damages surrounding components.

Unlike a typical fuel pump relay failure, this is not simply an aged part wearing out. The problem has been severe and widespread enough that General Motors issued Technical Service Bulletin 15-NA-051, which instructed dealers to trim the seat brackets and install a shorter, low-profile relay to relieve the pressure. However, this is a TSB, not a safety recall, so unless your car is under warranty, you are responsible for the repair cost. In this guide, we will walk you through exactly where the relay is, how to recognize the warning signs, how to test it, and how to replace it—plus what to do about the underlying seat frame issue so you do not have to repeat this repair.

Where Is the 2010 Buick Lucerne Fuel Pump Relay Located?

The fuel pump relay on the 2010 Buick Lucerne is not in the engine bay fuse box. It is located inside the rear underseat fuse block, which sits under the rear seat cushion on the driver's side. Specifically, it is identified as Relay #59, and the fuel pump fuse is Fuse #1 (20A) in the same box.

Step-by-Step to Access the Relay:

  1. Remove the rear seat cushion. The bottom cushion pulls straight up and forward. It is held in place by two or three clips. Put your hands under the front edge of the cushion, near where your knees would go, and pull up sharply with moderate force. It will pop loose. On the base model, there are no wiring connections, so you can set it aside.

  2. Find the black plastic cover. Once the seat is out, look at the floor pan on the driver's side. You will see a black plastic access cover screwed or snapped into the floor. This cover protects the rear underseat fuse block.

  3. Remove the cover. The cover typically has a simple latch or a couple of screws. Remove them and lift the cover off. You will now see the fuse block.

  4. Identify Relay #59. Inside the fuse block, look for the relay labeled #59. It is a standard mini relay with a gray or black body. It sits in a socket that is taller than the surrounding fuses. Right next to it, you will see Fuse #1, the 20-amp MINI fuse for the fuel pump.

Why the Fuel Pump Relay Fails So Often on the 2010 Lucerne

The 2010 Lucerne has a design flaw that causes repeated fuel pump relay failures. A known problem exists where the rear seat frame presses down on the top of the fuse box, causing the relay to make poor contact with its terminals. This poor connection creates arcing, which generates extreme heat. The heat melts the relay, the fuse box, and surrounding fuses.

One owner described it this way: "The spot where contact is made to the fuse box, is where the fuel pump relay is. Pressure from the seat bracket causes the pump relay to not make proper contact with the terminal, therefore causing the power to arc and get so hot that the relay starts smoking, melting the relay, fuse box and surrounding fuses."

Other causes of failure include:

  1. Current overload: If the fuel pump draws more current than the relay is designed to handle, the contacts overheat and burn out.

  2. Short circuit: A damaged wire touching the vehicle body can cause an overload.

  3. Age and wear: Over time, the electromagnetic coil and mechanical contacts simply wear out.

Real-world complaints reinforce this. One 2010 Lucerne owner reported that after driving home and letting the car cool for two hours, the starter would turn over but the engine would not start. They began to smell burning plastic inside the vehicle. After removing the back passenger seat bottom cushion, they checked the rear fuse box and found that the fuel pump relay had shorted and melted, with burn marks across the surface of the fuse box. Another owner reported that the fuse box under the driver's side passenger seat melted due to pressure put on it by the seat and various occupants or items, and the mechanic warned them not to place anything heavy (or allow a heavy person to sit) on that side of the back seat.

Symptoms of a Bad 2010 Buick Lucerne Fuel Pump Relay

How do you know if it is the relay and not the fuel pump itself? Here are the most common signs:

1. Engine cranks but will not start
You turn the key, the starter spins the engine, but it never fires up. You may not hear the fuel pump prime when you turn the key to the "ON" position.

2. Car stalls while driving
The engine suddenly dies at intersections, on the highway, or during normal driving. This is dangerous because you lose power steering and brakes.

3. Intermittent starting problems
Sometimes the car starts fine, other times it won't. This happens because the relay's internal contacts are worn and only make connection occasionally.

4. No fuel pump priming sound
When you turn the key to "ON" (without starting), you should hear a brief whirring sound from the rear of the car. If you don't hear it, the relay likely isn't sending power to the pump.

5. Burnt plastic smell or visible damage
Many owners report that the fuel pump relay gets so hot it melts the plastic housing and even the fuse box itself.

How to Test the 2010 Buick Lucerne Fuel Pump Relay

Before buying a new relay, test the old one. Here's how:

Step 1: Locate the relay. Remove the rear seat cushion and access the fuse box. The fuel pump relay is relay #59.

Step 2: Swap with a known good relay. Look for another relay in the same fuse box with the same part number and ratings. Good candidates include the park lamps relay (#58) or the trunk release relay (#67). Swap them and see if the fuel pump works.

Step 3: Listen for the pump. With the swapped relay in place, turn the key to "ON." If you hear the fuel pump prime, the old relay was bad.

Step 4: Test with a multimeter. If you have a multimeter, set it to ohms and check the relay's coil terminals (usually 85 and 86). You should see a reading between 50-120 ohms. If it is open (OL), the coil is dead.

How to Replace the 2010 Buick Lucerne Fuel Pump Relay

Replacing the relay is an easy and inexpensive fix that you can do yourself in under 30 minutes. Here is what to do:

  1. Remove the rear seat cushion as described above.

  2. Access the rear underseat fuse block by removing the black plastic cover.

  3. Remove the burnt or faulty relay #59. Pull it straight out of its socket. If the relay has melted, be careful not to break the surrounding fuse box plastic.

  4. Inspect the fuse box socket. If the relay melted, the socket terminals may be deformed or burnt. If the damage is severe, the entire fuse box may need replacement. One owner reported that the fuel pump relay shorted and melted, damaging adjacent fuses with burn marks across the surface of the fuse box.

  5. Install the new relay. Push the new relay firmly into the socket until it clicks into place. Use a high-quality replacement relay that matches the original specifications.

  6. Replace Fuse #1 (20A) if it is blown.

  7. Reinstall the cover and seat cushion. Make sure the seat cushion is properly seated and latched.

The Permanent Fix: Address the Seat Frame Issue

Replacing the relay alone is only a temporary fix. If you don't address the root cause, the new relay will eventually fail the same way. General Motors recognized this problem and issued Service Bulletin 15-NA-051, which instructs dealers to grind off about 5 mm from the rear seat latch to relieve the pressure on the fuse box. One owner who performed this fix noted that they had already done the GM TSB "grind off 5 mm from rear seat latch" before dealing with the burnt plastic of the overheating relay terminal.

If you are handy with tools, you can do this yourself:

  • Remove the rear seat cushion as described above.
  • Inspect the seat frame. Look for the bracket or latch that presses against the fuse box cover.
  • Grind off about 5 mm from the metal bracket where it contacts the fuse box cover. Use a grinder or a file.
  • Alternatively, install a low-profile relay. The TSB instructed dealers to install a shorter relay to provide more clearance.

This modification will prevent the seat frame from pressing down on the relay and causing the arcing that leads to melting.

What If the Fuse Box Is Already Damaged?

If the relay melted and damaged the fuse box, you may need to replace the entire rear underseat fuse block. This is more involved and more expensive. Several owners have reported having to do exactly this.

One owner reported that the fuse box under the driver's side passenger seat had melted due to pressure put on it by the seat and various occupants or items. The mechanic replaced the fuse box, relay, sensor, and fuel pump. Another owner reported having their fuse box replaced with a used one because GM did not have any new ones at any warehouse.

The fuse box replacement involves disconnecting the wiring harness, removing the old fuse block, and installing a new one. This is more complex and may require professional installation. However, it is a necessary step if the socket terminals are so damaged that a new relay cannot make a solid connection.

Fuel System Inspection After Relay Failure

When the fuel pump relay fails, it is not uncommon for the fuel pump itself to be damaged as well. The relay failure can cause the fuel pump to run erratically or not at all, which can lead to premature pump failure. Several owners have reported that both the relay and the fuel pump needed replacement after a relay failure.

Before replacing the fuel pump, check the fuel pressure with a gauge. One owner who had persistent fuel system issues replaced the relay and fuse box and then replaced the fuel pump, but the car still would not start. A forum responder asked what the fuel pressure readings were, noting that without proper diagnosis, you may be replacing parts unnecessarily.

Also, check the fuel pump relay socket for damage. A burnt relay may cause damage to the connection points where the relay plugs into the block, and that damage may make even a new relay fail quickly.

Recommended: KEMSO Fuel Pump for the 2010 Buick Lucerne

If you need to replace the fuel pump on your 2010 Buick Lucerne, we strongly recommend choosing a KEMSO brand fuel pump. KEMSO fuel pumps are high-performance units that are designed as OEM replacements, meaning they meet or exceed the original manufacturer's specifications for fit, function, and durability.

Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected. Whether your fuel pump failed due to the relay issue or simply because it reached the end of its service life, a KEMSO pump is a reliable choice.

You can browse the full range of KEMSO fuel pumps at https://www.kemsoracing.com/.

Final Thoughts

The 2010 Buick Lucerne fuel pump relay is a known weak point, and the failure is caused by a design flaw where the rear seat frame presses on the fuse box. If you experience any of the symptoms described in this guide, check the relay first. It is an easy, inexpensive fix that you can do yourself in under 30 minutes.

But do not forget the root cause. Grind off a small amount from the seat bracket and install a low-profile relay to prevent the problem from recurring. If the fuse box is already damaged, replace it as well. And if your fuel pump has also failed, consider a KEMSO replacement for long-term reliability.

For more information on quality fuel pumps and other automotive parts, visit https://www.kemsoracing.com/ today.


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