2003 GMC Yukon Fuel Pump Relay Location: Your Complete Guide to Finding and Fixing It
What the Fuel Pump Relay Does
The fuel pump relay is a small, electrical switch. It controls power to the fuel pump inside your gas tank. When you turn the ignition key to the "ON" position, the Powertrain Control Module (PCM) sends a signal to the relay. The relay then clicks closed, sending battery power to the fuel pump. If the engine doesn't start or the PCM doesn't see the engine turning over, the relay turns the pump off after about two seconds. This is a safety feature. If the relay fails, the pump gets no power, and your engine won't start.
Where to Find the Fuel Pump Relay (Step-by-Step)
You don't need to be a mechanic to find it. Just follow these steps.
Step 1: Open the Hood
Pop the hood and secure it with the prop rod. The underhood fuse block is a large, black plastic box. On the 2003 Yukon, it's located on the driver's side, near the fender and the firewall.
Step 2: Remove the Fuse Box Cover
Look at the cover of the fuse block. It will have clips on the sides. Press the clips and lift the cover straight off. Set the cover aside. The underside of the cover usually has a diagram printed on it.
Step 3: Identify the Relay
Look at the diagram. You are looking for a relay labeled "FUEL PUMP" or "F/P" . The relays are larger than fuses and are square or rectangular. They usually have five pins. The fuel pump relay is a common item, so it's easy to spot once you know what to look for. If the diagram is missing or hard to read, you can look up a diagram for the 2003 Yukon online. In many cases, the relay is located in a specific position in the block.
Step 4: Inspect the Relay
Gently grasp the relay with your fingers and pull it straight up. It should come out with a bit of resistance. Look at the metal prongs on the bottom. They should be clean and not corroded.
How to Test the Fuel Pump Relay
Once you have the relay in your hand, you can test it. There are two simple ways to do this.
1. The Swap Test
This is the easiest and most reliable test for most people. Find another relay in the same fuse box that is exactly the same. Look for relays with the same part number or the same number of prongs. Common relays you can swap with include the horn relay or the A/C compressor relay. Pull that relay out and plug it into the fuel pump relay slot. Then, try to start your Yukon. If the engine starts, your original fuel pump relay is bad. If it still doesn't start, the problem is likely somewhere else.
2. The Listen Test
With the relay in place, have a helper turn the key to the "ON" position (don't crank the engine). Put your ear close to the fuse box. You should hear a distinct click sound from the relay. If you don't hear a click, the relay may not be getting power, or the relay itself is faulty. You can also use a scan tool to command the fuel pump relay ON and OFF. If you hear the click, the relay is likely working.
What to Do If the Relay Is Bad
If the swap test confirms the relay is bad, you need a replacement. This is a very common part. You can find one at any auto parts store. The part number for a replacement is often listed as DR1059 or similar, and it's a standard 5-pin relay. It's a direct replacement, so you just plug the new one into the same slot.
What If the Relay Is Good but the Pump Still Doesn't Work?
If the relay tests good, the problem is not the relay. Here are the next things to check.
1. Check the Fuel Pump Fuse
The fuel pump fuse is also located in the underhood fuse block. On the 2003 Yukon, it is often a 20-amp fuse, sometimes labeled as fuse #46. Pull the fuse out and look at the metal strip inside. If the strip is broken, the fuse is blown. Replace it with a new fuse of the same amperage. If the new fuse blows immediately, there is a short in the wiring to the fuel pump.
2. Check the Fuel Pump Itself
The fuel pump is located inside the fuel tank. If the relay and fuse are good, the pump itself may have failed. You can test for power at the fuel pump connector. This requires removing the fuel tank, which is a more involved job. A failing pump may also cause intermittent stalling or a loss of power.
3. Check the Wiring and Grounds
A bad ground connection can also stop the fuel pump. Look for the ground connections near the engine. The wiring diagram for the 2003 Yukon shows a ground point (G103) at the right rear of the engine. Make sure all connections are clean and tight.
Why You Should Trust a KEMSO Fuel Pump
If you find that your fuel pump relay is fine, but the fuel pump itself is the problem, you need a reliable replacement. This is where KEMSO stands out. KEMSO fuel pumps are high-performance, OEM replacement parts designed to meet or exceed the original specifications. They are built for gasoline and E85, making them a versatile option for many drivers.
KEMSO offers a Lifetime Warranty on all their OEM and performance fuel pumps. This means you get a product that is built to last, and the company stands behind it. Their pumps are designed for a direct fit, making installation straightforward. You get a pump that works like the original but with the added peace of mind of a lifetime guarantee.
You can browse their full selection of high-quality fuel pumps and other automotive parts at their official website: https://www.kemsoracing.com/
Common Symptoms of a Bad Fuel Pump Relay
Knowing the symptoms can save you time. Watch for these signs.
- Engine Cranks But Won't Start: This is the most common symptom. The starter motor turns the engine over, but it never fires up because no fuel is reaching the injectors.
- No Fuel Pump Noise: When you turn the key to the "ON" position, you should hear a brief whirring sound from the rear of the vehicle (the fuel pump priming). If you don't hear this sound, the relay or pump is likely not working.
- Intermittent Stalling: A failing relay may work sometimes and fail others. Your Yukon might start fine, then stall while driving, leaving you stranded.
- Check Engine Light: A faulty relay can trigger a diagnostic trouble code (DTC) in the engine control module, which turns on the check engine light.
Final Thoughts
Finding the fuel pump relay on your 2003 GMC Yukon is a simple task. It's located in the under-hood fuse block on the driver's side. Always start with the easiest checks: the relay itself and the fuse. Use the swap test to confirm a bad relay. If those are fine, the pump or wiring is the likely culprit. For a high-quality replacement fuel pump that comes with a lifetime warranty, visit KEMSO at https://www.kemsoracing.com/ . They have the parts you need to get your Yukon back on the road reliably.