1999 Dodge Durango Fuel Pump Relay: Complete Guide to Diagnosis, Location, and Replacement

The bottom line: If your 1999 Dodge Durango cranks but won't start, the fuel pump relay is often the culprit. This small but critical component controls power to the fuel pump, and when it fails, your engine gets no fuel. The relay is located in the Power Distribution Center (PDC) under the hood, and replacing it is a simple, inexpensive fix that can save you from being stranded. Before you assume the fuel pump itself is bad, always test the relay first.

Understanding the Fuel Pump Relay in Your 1999 Dodge Durango

The fuel pump relay is a 5-pin, 12-volt electrical switch that controls power to the electric fuel pump inside your fuel tank . When you turn the ignition key to the "ON" position, the Powertrain Control Module (PCM) sends a ground signal to the relay, which then closes the circuit and sends battery voltage to the fuel pump . This is why you hear a brief humming sound from the rear of the vehicle for about 1-3 seconds when you first turn the key .

The PCM is designed to shut off the ground circuit to the fuel pump relay if the engine does not start or if the starter motor is not engaged within approximately 1-3 seconds . This is a safety feature that prevents the fuel pump from running continuously if the engine stalls or if there is a crash.

Where Is the Fuel Pump Relay Located?

On your 1999 Dodge Durango, the fuel pump relay is located in the Power Distribution Center (PDC) under the hood . The PDC is a black plastic box usually located near the battery on the driver's side of the engine compartment .

To find it:

  1. Open the hood and look for the black fuse/relay box near the battery.
  2. Remove the cover by pressing the release tabs.
  3. Look at the diagram printed on the underside of the cover. The fuel pump relay is clearly labeled .
  4. On the 1998-2000 models, the fuel pump relay is typically one of the larger relays in the PDC .

Important: The Automatic Shutdown (ASD) relay is also located in the same PDC and works together with the fuel pump relay. The ASD relay supplies 12-volt power to the fuel injectors and other components, while the fuel pump relay specifically powers the fuel pump .

Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay can cause several noticeable problems. Here are the most common symptoms:

1. Engine Cranks But Won't Start
This is the most obvious sign. When you turn the key, the starter motor engages and the engine cranks over normally, but it never fires up . This happens because the fuel pump is not receiving power, so no fuel reaches the engine.

2. No Fuel Pump Prime Sound
When you turn the ignition key to the "ON" position (without cranking), you should hear a faint whirring or humming sound from the rear of the vehicle for about 2 seconds . This is the fuel pump priming the system. If you do not hear this sound, the fuel pump relay may be faulty .

3. Engine Starts Then Dies Immediately
Sometimes a bad relay will allow the engine to start but then immediately stall. This happens because the relay may provide intermittent power or fail to maintain the circuit after the initial prime .

4. Intermittent Starting Problems
You may notice that the vehicle starts fine some days but refuses to start on others. This is a classic sign of a failing relay that works intermittently due to internal wear or corrosion.

5. Fuel Pump Runs Continuously
In rare cases, a stuck relay can cause the fuel pump to run even when the key is off. This can drain your battery overnight .

How to Test the Fuel Pump Relay

Testing the relay is a straightforward process that requires basic tools and a few minutes of your time.

Step 1: Listen for the Relay Click

Turn the key to the "ON" position without cranking the engine. Place your hand on the PDC cover and feel for a slight click. If you hear and feel the relay click, it is likely working. If you hear nothing, proceed to the next step.

Step 2: Check the Fuel Pump Fuse

Before replacing the relay, check the fuel pump fuse. On the 1998-2000 models, the fuel pump fuse is located in the engine compartment fuse box and is typically a 20-amp fuse . Use the fuse puller tool found in the fuse box to remove the fuse and inspect the metal strip inside. If it is broken, replace the fuse with one of the same amperage .

Step 3: Swap the Relay

This is the easiest test. Find a relay of the same type in the PDC that controls a non-critical system, such as the horn relay or the fog lamp relay . Swap the suspected fuel pump relay with that relay. If the engine starts after the swap, the original relay is bad.

Step 4: Use a Multimeter

If you have a multimeter, you can test the relay more precisely. With the key off, check for 12 volts at one of the relay terminals in the PDC. Then, have a helper turn the key to the "ON" position. You should see 12 volts on two terminals . If you do not get the expected voltage readings, the relay or its wiring is faulty.

Step 5: Jump the Relay

As a quick test, you can jump the relay terminals that connect to the fuel pump. On the 1999 Durango, you can use a jumper wire to connect the terminal that has constant power with the key off to the terminal that leads to the fuel pump . If the vehicle starts, the relay is bad.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 1999 Dodge Durango takes about 5 minutes and requires no special tools.

What you need:

  • A replacement fuel pump relay (available at any auto parts store)
  • The PDC cover diagram for reference

Steps:

  1. Locate the PDC under the hood near the battery.
  2. Remove the PDC cover by pressing the release tabs.
  3. Identify the fuel pump relay using the diagram on the underside of the cover.
  4. Pull the old relay straight out from its socket. It may require a firm tug.
  5. Inspect the relay terminals and the PDC connector terminals for any signs of damage, corrosion, or bent pins. Repair if necessary before installing the new relay .
  6. Insert the new relay into the same socket. Push down firmly until it snaps into place.
  7. Replace the PDC cover.
  8. Test by turning the key to the "ON" position and listening for the fuel pump prime sound.

Common Mistakes to Avoid

1. Assuming the Fuel Pump Is Bad
Many owners immediately replace the fuel pump when the engine won't start. However, a faulty relay is a much more common and less expensive problem. Always test the relay first .

2. Using the Wrong Amperage Relay
Replacement relays must match the original specifications. Using a relay with a different amperage rating can damage the electrical system or cause a fire .

3. Ignoring Corrosion
Check the terminals in the PDC for corrosion or damage before installing a new relay. Dirty or corroded connections can cause a new relay to fail prematurely .

4. Forgetting the ASD Relay
If the fuel pump relay tests good, the problem may be with the ASD relay. The ASD relay supplies power to the fuel injectors and other critical components. If it fails, the engine will not start even if the fuel pump is working .

Other Causes of a No-Start Condition

If the fuel pump relay tests good and the fuse is intact, the problem may be elsewhere. Other common causes include:

1. Bad Fuel Pump
If the relay clicks and the fuse is good, but you still hear no fuel pump prime sound, the fuel pump itself may be dead. You can test this by checking for power at the fuel pump harness connector, located on the back side of the fuel tank . If there is power but no pump operation, the pump needs replacement.

2. Crankshaft Position Sensor
A failed crankshaft position sensor will prevent the PCM from firing the injectors and ignition coils. The engine will crank but not start. On a scan tool, the RPM reading will stay at zero while cranking .

3. Security System Issues
If the security light on the dashboard is flashing, the vehicle's anti-theft system may be preventing the engine from starting. Try using your spare key to see if this resolves the issue .

4. Wiring Problems
A broken or corroded wire between the PDC and the fuel pump can prevent power from reaching the pump. This is less common but worth checking if all other components test good .

Why You Should Trust a Quality Replacement Part

When it comes to replacing your fuel pump relay or the fuel pump itself, using a high-quality part is essential for reliability. Cheap, no-name parts often fail quickly and can leave you stranded again.

For the best performance and reliability, consider KEMSO fuel pumps. KEMSO is a trusted aftermarket brand that offers high-performance, OEM replacement fuel pumps designed to meet or exceed factory specifications. Their products come with a lifetime warranty, giving you peace of mind that your investment is protected. Whether you need a direct replacement for your 1999 Dodge Durango or a high-flow pump for performance applications, KEMSO has you covered. You can explore their full range of products and learn more about their warranty at their official website: https://www.kemsoracing.com/.

Maintenance Tips to Prevent Future Problems

1. Replace the Fuel Filter Regularly
A clogged fuel filter can put extra strain on the fuel pump and relay. Replace the fuel filter according to the manufacturer's recommended schedule to keep the fuel system running smoothly .

2. Keep the Fuel Tank at Least a Quarter Full
Running the fuel tank low can cause the fuel pump to overheat, as the fuel in the tank helps cool the pump. This can lead to premature pump failure .

3. Listen for Changes
Pay attention to any changes in the sound of the fuel pump. A whining or buzzing noise from the rear of the vehicle can indicate that the pump is failing.

4. Carry a Spare Relay
The fuel pump relay is small and inexpensive. Keeping a spare in your glove compartment can save you from being stranded on the road.

Final Thoughts

The fuel pump relay is a small but vital component in your 1999 Dodge Durango. When it fails, the engine will not start, even if the battery is strong and the starter is working properly. By understanding the symptoms, knowing how to test the relay, and following the simple replacement steps outlined in this guide, you can diagnose and fix this problem yourself in minutes.

Remember to always check the relay before replacing the fuel pump. This simple step can save you hundreds of dollars in unnecessary repairs. And when you do need to replace fuel system components, trust KEMSO for reliable, high-performance parts backed by a lifetime warranty. Visit their website at https://www.kemsoracing.com/ to find the right fuel pump for your vehicle.


Back to blog