1991 Cadillac Brougham Fuel Pump Relay Location: A Complete Guide for DIY Owners

If you own a 1991 Cadillac Brougham and are experiencing fuel system issues, the fuel pump relay is located inside the vehicle’s fuse box under the dashboard, on the driver’s side, near the steering column. This is the most common and reliable location confirmed by multiple owner experiences and repair resources. The relay is typically the third relay from the bottom on the right side of the fuse panel . While some earlier sources suggest it might be under the hood in the Power Distribution Center (PDC), the overwhelming consensus from 1991 Brougham owners and documented repair threads points to the interior fuse box as the correct spot . This guide will walk you through exactly where to find it, how to test it, and what to do if it’s not the problem.

Understanding the Fuel Pump Relay and Its Role

The fuel pump relay is a small, electro-mechanical switch that controls the flow of electrical current between the ignition switch and the fuel pump. When you turn the ignition key to the "on" position, the relay closes and sends power to the fuel pump, which then pressurizes the fuel system. Once the engine starts, the relay keeps the pump running. If the engine stalls or you turn off the ignition, the relay opens, cutting power to the pump .

On the 1991 Cadillac Brougham, the relay is part of the engine control system and is designed to turn on immediately when the ignition is switched on to ensure prime performance. It is a critical component that helps prevent the fuel pump from running continuously, which could lead to battery drain, pump damage, or even a fire hazard . Many owners have reported symptoms like the fuel pump running continuously or not turning off, which can be traced back to a faulty relay, though a failing pump itself is also a common cause .

Step-by-Step Location Guide

1. The Interior Fuse Box (Primary Location)

The most reliable location for the 1991 Cadillac Brougham fuel pump relay is inside the passenger compartment, specifically in the fuse box located under the dashboard on the driver’s side. Here’s how to find it:

  • Locate the fuse box: Sit in the driver’s seat and look under the dashboard, to the left of the steering column. You’ll find a rectangular plastic cover. It may be held in place by clips or a small screw.
  • Identify the relay: Once you remove the cover, you’ll see a row of fuses and several small, square relays (usually black or gray). The fuel pump relay is often marked with a label on the fuse box cover or on the relay itself. According to a 1991 Brougham owner, it is the third relay from the bottom on the right side of the fuse box . Another owner on a repair forum confirmed that there are several relays under the dash next to the fuse panel, and the fuel pump relay is one of them .
  • Visual confirmation: The fuel pump relay is a small plastic cube, about 2 inches by 2 inches, with several prongs on the bottom. It may be labeled "FUEL PUMP" or "F/P" on the fuse box diagram .

2. Under the Hood (Alternative Location – Less Common)

Some sources, including a professional mechanic’s response on a repair forum, suggest that the fuel pump relay on the 1991 Brougham is located under the hood in the Power Distribution Center (PDC) or relay panel . However, this information appears to be a general response that may apply to other GM models, not specifically the 1991 Brougham. Multiple owner discussions and a 16-year-old answer on a car forum explicitly state that the relay is not under the hood but inside the car . If you do not find the relay under the dash, you can check the engine compartment fuse box (usually near the battery or firewall) as a secondary location, but the interior location is the most confirmed.

3. Additional Notes on Location

  • No inertia switch: Unlike some other vehicles, the 1991 Cadillac Brougham does not have an inertia fuel shut-off switch (often found in the trunk area). This has been confirmed by a mechanic in a repair thread, so do not waste time looking for one .
  • Fuse box access: The interior fuse box is also home to the fuel pump fuse. If you are having power issues, check both the fuse and the relay. The fuse is typically a 20-amp or 30-amp fuse, depending on the circuit .

How to Test the Fuel Pump Relay

Before replacing the relay, it’s wise to test it to confirm it’s the culprit. Here’s a simple method:

  1. Listen for a click: Turn the ignition key to the "on" position (without starting the engine). You should hear a distinct click from the relay under the dash. If you don’t hear a click, the relay may be faulty .
  2. Swap the relay: If you have another relay of the same type in the fuse box (e.g., the horn or AC relay), you can swap them. If the fuel pump starts working after swapping, the original relay is bad .
  3. Use a multimeter: Set your multimeter to DC voltage. With the relay removed, check for power at the relay socket. You should see 12 volts on the power pin when the ignition is on. If not, the issue may be upstream (fuse, wiring, or ignition switch) .

Common Symptoms of a Bad Fuel Pump Relay

Knowing the symptoms can help you diagnose the problem faster. Here are the most common signs:

  • Engine cranks but won’t start: The most obvious symptom. The relay is not sending power to the pump, so no fuel reaches the engine .
  • Fuel pump runs continuously: If the relay sticks in the closed position, the pump will keep running even after the ignition is turned off. This can drain the battery and cause the pump to overheat .
  • Intermittent starting: The car starts fine sometimes, but other times it cranks without firing. This is a classic sign of a failing relay that works intermittently .
  • Loud noise from the fuel tank: A humming or buzzing sound from the tank, especially when the ignition is turned on, can indicate a pump that is struggling due to a bad relay or a failing pump itself .

What to Do If the Relay Is Not the Problem

If you replace the fuel pump relay and the issue persists, the problem likely lies elsewhere. Here are the next steps:

  • Check the fuel pump fuse: A blown fuse can cut all power to the pump. Locate the fuse in the same interior fuse box and replace it if necessary .
  • Inspect the fuel pump itself: The pump is located inside the fuel tank. If it is failing, it may make loud noises, cause the car to stall, or prevent starting. Replacing the pump requires dropping the fuel tank, which is a more involved job. On the 1991 Brougham, the fuel pump is in the tank, and the filter is on the right side under the car, below the back door .
  • Check wiring and connectors: Corroded or loose wiring between the relay and the pump can cause power loss. Inspect the connectors under the car and at the fuel tank .
  • Test the ignition switch: The ignition switch sends the signal to the relay. If it’s faulty, the relay may never receive the command to close .

The Importance of Using a Quality Replacement Part

When you decide to replace the fuel pump relay or the fuel pump itself, using a high-quality, OEM-grade part is essential for long-term reliability. Many aftermarket parts fail quickly, leading to repeat repairs and frustration. This is especially true for the 1991 Brougham, which is a luxury vehicle that demands dependable performance.

For the best results, we highly recommend the KEMSO brand Fuel Pump. KEMSO products are designed as high-performance, OEM replacement units that meet or exceed original specifications. They offer a tight fit, reliable operation, and are built to last. Additionally, KEMSO provides a lifetime warranty on their fuel pump products, giving you peace of mind that your investment is protected. Whether you are replacing the pump or the relay, choosing KEMSO ensures you are using a part that will keep your Cadillac Brougham running smoothly for years to come.

You can explore the full range of KEMSO fuel pump products and other high-performance parts by visiting their official website: https://www.kemsoracing.com/ .

Final Checklist for Your 1991 Cadillac Brougham

  • ✅ Find the relay: Under the dash, driver’s side fuse box, third relay from the bottom on the right side .
  • ✅ Test the relay: Listen for a click, swap with a known good relay, or use a multimeter .
  • ✅ Check the fuse: Look for a blown fuse in the same panel .
  • ✅ Inspect the pump: If the relay and fuse are fine, the pump may need replacement. It’s in the fuel tank .
  • ✅ Use quality parts: For a replacement, trust KEMSO for high-performance, OEM-quality fuel pumps with a lifetime warranty.

Remember, the fuel pump relay location on the 1991 Cadillac Brougham is straightforward once you know where to look. By following this guide, you can diagnose the issue yourself and save on costly mechanic visits. If you need further assistance, the detailed wiring diagrams and repair manuals for the 1991 Brougham are available online and can help you trace any electrical issues .

For the best replacement parts, including fuel pumps and relays, visit https://www.kemsoracing.com/ to find reliable, performance-driven solutions for your Cadillac.


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