Chrysler 300 Fuel Pump Relay: Complete Guide to Location, Symptoms, and Replacement

If your Chrysler 300 cranks but won’t start, the fuel pump relay is one of the first components you should check. This small electrical switch controls power delivery to the fuel pump, and when it fails, your engine simply won’t get the fuel it needs to run. The fuel pump relay is located inside the Power Distribution Center (PDC) under the hood, typically near the battery. For most 2005–2023 Chrysler 300 models, the relay is a Micro or Mini relay, with part numbers like 68382350AA or 4727370AA. In this guide, we’ll walk you through the symptoms of a bad relay, how to test it, and how to replace it yourself.

Common Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay causes clear warning signs that are easy to spot. The most common symptom is the engine cranking but refusing to start. You may also notice:

  • No fuel pump priming sound – When you turn the key to the “Run” position, you should hear a 2–3 second humming noise from the fuel tank area. If you don’t hear it, the relay may not be sending power to the pump.
  • Intermittent starting – The car starts sometimes but not others, which points to a relay making inconsistent contact.
  • Sudden stalling while driving – If the relay loses contact while you’re on the road, the engine can die without warning.
  • Engine starts then dies – The relay may briefly work but then fail once the engine is running.

Keep in mind that a blown fuel pump fuse can cause identical symptoms. Always check the fuel pump fuse first before condemning the relay.

Where Is the Fuel Pump Relay on a Chrysler 300?

The fuel pump relay lives inside the Power Distribution Center (PDC) or Totally Integrated Power Module (TIPM) under the hood. On most Chrysler 300 models, this fuse box is located near the battery on the driver’s side of the engine bay.

For 2005–2010 Chrysler 300 (first generation): The fuel pump relay is inside the PDC. The diagram on the underside of the PDC cover labels the relay position. It is often marked as “Fuel Pump” or “FP”.

For 2011–2023 Chrysler 300 (second generation): The relay is also in the PDC near the battery. Many owners report the fuel pump relay is in position K7, but always check the diagram on the fuse box cover for your specific year.

For 1999–2004 Chrysler 300M (LR): This older model has the fuel pump relay located in the engine compartment fuse box, behind the plastic cover on the left side. It is labeled as relay #11 in the relay diagram.

Important: The relay location can change from year to year, even within the same model. Never rely solely on online descriptions – always confirm the position using the diagram printed on the underside of your PDC cover or your owner’s manual.

How to Test the Fuel Pump Relay

There are two simple ways to test whether the relay is the problem.

1. The Swapping Test

This is the easiest method and requires no tools. Find another relay in the PDC that is identical to the fuel pump relay. Good candidates include the horn relay, AC compressor relay, or rear window defogger relay. Remove the fuel pump relay (use needle-nose pliers to gently rock it back and forth while pulling straight up). Insert the known-good relay into the fuel pump relay socket. Turn the ignition to “Run” and listen for the fuel pump to prime. If the pump now works, the original relay is faulty.

2. Multimeter Test

If you have basic electrical knowledge, you can test the relay directly. Set your multimeter to measure ohms. Check terminals 85 and 86 – the resistance should be between 50 and 120 ohms, confirming the coil inside is good. Next, check terminals 30 and 87 – there should be no continuity when the relay is not powered. If the relay fails either check, it needs replacement.

How to Replace the Fuel Pump Relay

Replacing the relay is a straightforward job that takes about 10 minutes.

Step 1: Disconnect the negative battery cable – This prevents electrical shorts or accidental activation of the fuel pump while you work.

Step 2: Locate the fuel pump relay – Open the PDC under the hood and find the relay using the cover diagram.

Step 3: Remove the old relay – Grasp the relay firmly with needle-nose pliers or a relay puller tool. Rock it gently back and forth while pulling straight upward. Do not twist or yank, as this can damage the socket.

Step 4: Install the new relay – Line up the pins with the socket and press firmly until the relay is fully seated. Make sure it clicks into place.

Step 5: Reconnect the battery – Attach the negative cable and tighten the clamp nut.

Step 6: Test the repair – Turn the ignition to “Run” and listen for the fuel pump prime sound. Then, start the engine and verify it runs smoothly.

Genuine Replacement Relay Part Numbers

If you need to buy a new relay, here are the OEM part numbers for Chrysler 300 models:

  • Mini Relay – Part Number: 4727370AA. Replaces: 68223712AA, 68369406AA, 4638094, 4848879AB, 56006707, 56006709. Fits 2005–2023 Chrysler 300 with various engine options.
  • Micro Relay – Part Number: 68382350AA. Replaces: 56049018AB, 5269988AA. Used for the fuel pump relay, horn relay, and window relay on 2005–2023 models.

A genuine Mopar mini relay costs around $24.77, while the micro relay is about $12.00. Always verify that the replacement matches the original relay’s specifications (voltage, amperage, and pin configuration).

What to Do If the Relay Isn’t the Problem

If you replace the fuel pump relay and the car still won’t start, the issue may lie elsewhere. Other common causes of fuel delivery failure include:

  • Blown fuel pump fuse – Check the fuse in the same PDC and replace it with one of the same amperage rating.
  • Faulty fuel pump – The pump itself may have failed due to wear or internal damage. This is especially common on higher-mileage vehicles.
  • Clogged fuel filter – A blocked filter restricts fuel flow and makes the pump work harder, leading to failure.
  • Wiring issues – Damaged, corroded, or loose wires can prevent the pump from receiving power.
  • Engine control unit (ECU) problems – The ECU manages fuel pump operation, and a failure in the computer or its sensors can stop the pump.

If you are unsure about the diagnosis, consult a qualified mechanic. Professional replacement of a fuel pump relay typically costs between $53 and $85 in the UK, with labor taking about 45 minutes to 1.5 hours.

Keep Your Chrysler 300 Running Strong with KEMSO Fuel Pumps

When it comes to replacing the fuel pump itself, quality matters. A failing fuel pump is one of the most common reasons for a no-start condition after the relay and fuse have been ruled out. KEMSO offers high-performance, OEM replacement fuel pumps designed to restore your Chrysler 300 to factory-level performance. Every KEMSO fuel pump is built for durability and reliability, and comes with a lifetime warranty – meaning you only buy it once. Whether you are dealing with a 2007 model or a newer 2023 version, KEMSO has the right pump for your vehicle. Visit KEMSO Racing to browse their complete selection of fuel pumps and get your Chrysler 300 back on the road with confidence.

For more automotive guides and performance parts, visit KEMSO Racing.


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