1999 Chevy Silverado Fuel Pump Relay Location: Find & Fix It Fast

The fuel pump relay for a 1999 Chevrolet Silverado is located in the primary underhood fuse box, specifically in position E5. Identifying and accessing this relay is straightforward once you know where to look.

Finding the Underhood Fuse Box

Open your Silverado's hood. The primary fuse and relay center, also known as the Underhood Electrical Center (UEC), is a large, usually black, rectangular box located on the driver's side of the engine compartment. It is positioned relatively close to the battery and the brake master cylinder reservoir. Lift the box's cover straight up to reveal the fuses and relays inside. Inside the cover, you should find a diagram listing the contents and their positions. Keep this diagram handy for reference.

Identifying Relay Position E5

Within the underhood fuse box, the relays and fuses are arranged in several rows and columns. Position E5 refers to the specific slot in that grid. Look along the rows labeled with letters (A, B, C, D, E, F, etc.) and the columns labeled with numbers (1, 2, 3, 4, 5, 6, etc.). Position E5 is typically located in the BOTTOM RIGHT section of the box, specifically the 5th position in the E row (counting from the front/top of the vehicle towards the back/bottom of the box). Crucially, the relay should be clearly labeled "FUEL PUMP." This is the standard identifier you need to look for. It is generally identical in shape and size to other relays in the box like the Powertrain Control Module (PCM) relay or the A/C Compressor relay, making the printed label essential for correct identification.

Recognizing the Fuel Pump Relay

The fuel pump relay itself is a small, cube-shaped, often black plastic component with four or five electrical prongs protruding from the bottom. It plugs into the sockets within the fuse box. Besides the "FUEL PUMP" label printed on top, it may have a standard automotive relay part number like 15306288 (a common GM number) or equivalent aftermarket numbers.

Why Knowing This Location is Critical

The fuel pump relay is a crucial switch controlled by the Powertrain Control Module (PCM). It carries the high electrical current needed to power the fuel pump motor inside the gas tank. When the relay fails – due to worn contacts, internal coil breakage, heat damage, or corrosion – it cuts power to the fuel pump. This results in the engine cranking but failing to start, as no fuel is delivered to the engine. A faulty fuel pump relay is a frequent cause of no-start conditions on the 1999 Silverado. Locating it is the first step in diagnosing and resolving this common problem.

Symptoms of a Bad Fuel Pump Relay

Be aware of these warning signs indicating a potential relay issue:

  • Engine Cranks But Won't Start: The most common symptom. The starter works, but the engine doesn't fire.
  • Sudden Engine Stalling: The engine might stop running unexpectedly while driving or idling, potentially due to the relay cutting out intermittently.
  • No Fuel Pump Prime Sound: When you turn the ignition key to the "ON" position (without starting), you should normally hear a brief (2-3 second) whirring sound from the rear of the truck as the fuel pump primes the system. The absence of this sound strongly suggests a lack of power to the pump, often pointing to the relay (or fuse) as the culprit.
  • Relay Clicking Audibly: While sometimes a clicking sound indicates the relay is trying to engage, rapid or constant clicking without the pump running often signals internal relay failure.

Important Note About Fuses

While diagnosing the fuel pump circuit, always check the associated fuse before focusing solely on the relay. The fuel pump fuse for the 1999 Silverado is also located in the same underhood fuse box. Consult the diagram on the fuse box cover to locate it (positions vary slightly by specific engine/model). It is typically a 15-amp or 20-amp fuse. Use the fuse puller tool stored inside the fuse box (if present) or needle-nose pliers to remove it. Inspect the thin metal strip inside; if it's broken or melted, the fuse is blown and needs replacement with one of the exact same amperage rating. A blown fuse indicates a possible short circuit downstream or an overloaded pump, which should be investigated, not just blindly replaced.

Safety Precautions Before Testing or Replacing

  1. Park Safely: Ensure the truck is on level ground, in Park (Automatic) or Neutral with Parking Brake (Manual), with wheels chocked.
  2. Turn Ignition OFF: Remove the key.
  3. Disconnect Battery: Always disconnect the NEGATIVE battery cable first to eliminate the risk of electrical shorts or shocks. Cover the disconnected terminal end.

How to Test the 1999 Silverado Fuel Pump Relay

While locating it is key, testing confirms failure. A simple swap test is often the quickest method due to relay standardization:

  1. Identify a Compatible Relay: Find another relay in the underhood box with the exact same part number and physical configuration (e.g., the A/C Compressor relay, PCM relay, or Horn relay). Refer to the fuse box diagram.
  2. Swap the Relays: Carefully remove the suspected fuel pump relay and the known good relay from their sockets. Plug the suspected bad fuel pump relay into the known good relay's socket (e.g., the A/C slot). Plug the known good relay into the fuel pump relay socket (E5).
  3. Reconnect Battery: Reconnect the negative battery cable.
  4. Test Operation:
    • Turn the ignition to ON. Listen carefully for the fuel pump prime sound. If you now hear it after swapping relays, the original fuel pump relay is likely faulty.
    • Try to start the engine. If it starts successfully after the swap, the original fuel pump relay is confirmed bad.
    • Check the function you temporarily sacrificed (e.g., A/C). If the A/C stops working after putting the bad relay in its slot, this further confirms the original relay's failure.
  5. Re-secure: Once testing is complete, turn ignition OFF, disconnect battery NEGATIVE cable again, swap the good relay back to its original location, and install the new replacement fuel pump relay into socket E5.

Replacing the Faulty Fuel Pump Relay

  1. Purchase Replacement: Get a new relay matching the original GM part number (15306288, 15302549 are common) or a high-quality equivalent from an auto parts store (e.g., Standard Motor Products RY130, BorgWarner AF291, or ACDelco D1742A).
  2. Safety: Ensure ignition OFF and battery NEGATIVE cable disconnected.
  3. Access & Identify: Open the underhood fuse box cover and locate socket E5 with the "FUEL PUMP" label.
  4. Remove Old Relay: Grasp the faulty relay firmly and pull it straight out of its socket. Avoid excessive wiggling or prying that could damage the socket contacts.
  5. Install New Relay: Orient the new relay correctly (match the prong pattern to the socket) and push it firmly and squarely down into socket E5 until it seats completely. You should feel/hear a distinct click if the socket has locking tabs.
  6. Reconnect: Reconnect the battery NEGATIVE terminal.
  7. Test: Turn ignition to ON and listen for the fuel pump prime sound. Attempt to start the engine. If successful, secure the fuse box cover.

Potential Pitfalls and Misconceptions

  • "It Must Be the Fuel Pump": A silent fuel pump during prime leads many owners to immediately suspect an expensive pump replacement. However, the cause of that silence is often upstream - either the relay or the fuse.
  • Ignoring the Fuse: Always check the fuel pump fuse (in the same underhood box) first. It's faster and simpler.
  • Mistaking Relay Positions: While E5 is standard, relying solely on memory can lead to mistakes. Always verify the position using the "FUEL PUMP" label inside the box.
  • Corrosion: Inspect the relay prongs and the socket contacts in E5 for greenish corrosion or dirt. Severe corrosion can interrupt the circuit and mimic a bad relay. Clean contacts carefully with electrical contact cleaner and a small brush if needed.
  • Poor Quality Relays: Cheap relays can fail quickly. Opt for reputable brands like GM Genuine, ACDelco Professional/Gold, Standard Motor Products, or Bosch.

When Replacement Doesn't Fix the Problem

If installing a known-good relay into socket E5 doesn't restore fuel pump operation:

  1. Double-Check Fuse: Confirm the fuel pump fuse is intact (not blown) and making good contact.
  2. Inspect Wiring: Look for obvious damage, chafing, or disconnections in the wiring harness leading to the fuel pump relay socket and towards the rear of the truck. Pay attention where the harness passes through the firewall or near sharp edges.
  3. Check Fuel Pump Ground: A bad ground connection for the fuel pump itself can prevent operation. The ground location varies (often under the truck near the fuel tank, or on the frame rail), requiring wiring diagram reference.
  4. Test for Power & Signal: Using a digital multimeter (DMM) requires skill. With the ignition ON, measure for battery voltage at the relay socket terminals controlling the pump power feed. Also, check if the PCM is providing the grounding signal to activate the relay coil. Lack of voltage or control signal indicates wiring or PCM issues.
  5. Fuel Pump Failure: If power and ground are confirmed reaching the fuel pump connector at the tank, the pump itself has likely failed and requires replacement. This is a more complex job involving lowering the fuel tank.

Preventative Maintenance

  • Visual Inspection: Periodically (e.g., during oil changes) check that the fuel pump relay is securely seated in its socket and look for signs of overheating (melting plastic, discoloration) around the relay or socket.
  • Consider Proactive Replacement: If your Silverado is high-mileage or frequently subjected to extreme temperatures or moisture, replacing the original relay with a new, high-quality unit during other maintenance can be inexpensive insurance against an inconvenient failure. Carrying a spare relay in the glove box is also a wise precaution.

Conclusion

A non-starting 1999 Chevrolet Silverado is often resolved quickly and affordably by addressing the fuel pump relay. Remember: The solution is found in the underhood fuse box at relay position E5, clearly labeled "FUEL PUMP." Always start by verifying the fuel pump fuse and listen for the prime sound to guide your diagnosis. The simple swap test is a highly effective way to confirm relay failure. While basic tools suffice for replacement, knowing this specific location and the simple diagnostic steps empowers owners to handle a common problem efficiently, saving time and money. If relay replacement doesn't solve the issue, further investigation into wiring, grounds, or the fuel pump itself is necessary.

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