2008 Jeep Commander Fuel Pump Relay Location: A Complete Guide for DIY Owners

The bottom line up front: On a 2008 Jeep Commander, the fuel pump relay is located inside the engine compartment fuse box (also called the Integrated Power Module, or IPM), which sits on the left side of the engine bay near the battery. The specific relay, labeled R7, sits in the second fuse box section, and it controls power to the fuel pump so the engine gets fuel when you turn the key. If your Commander cranks but won't start, or stalls while driving, the fuel pump relay is one of the first things you should inspect.

The 2008 Jeep Commander, part of the XK series produced from 2006 through 2010, uses a relay system that manages power to the fuel pump. When you turn the ignition, the Powertrain Control Module (PCM) sends a signal that closes the relay, allowing battery power to flow to the fuel pump. This primes the fuel system and keeps fuel flowing while the engine runs. When the relay fails, the fuel pump loses power, which means no fuel reaches the injectors, and the engine will not start even though it cranks normally.

Knowing exactly where this relay lives and how to test it can save you a tow bill and a trip to the shop. This guide walks you through the location, how to confirm the relay is bad, how to replace it, and what to do if the relay is not the problem.

Where Exactly Is the Fuel Pump Relay on a 2008 Jeep Commander?

The 2008 Jeep Commander has two fuse boxes: one in the passenger compartment and one in the engine compartment. The fuel pump relay is not in the cabin fuse panel. It lives in the engine compartment in the second fuse box, which some manuals refer to as "Engine Compartment Fuse Box No. 2".

Here is how to find it step by step:

  1. Open the hood and look to the left side of the engine bay, near the battery. You will see a black plastic box with a lid. This is the Integrated Power Module (IPM). On the 2008 Commander, there are actually two fuse box sections under the hood–the main Power Distribution Center and a second smaller box. The fuel pump relay is in that second box.

  2. Remove the lid of the fuse box. The underside of the lid has a diagram that labels each fuse and relay. Look for a small square relay labeled "Fuel Pump" or the number R7. On the 2008–2010 models, the layout is clearly marked, and R7 is the fuel pump relay.

  3. Identify the relay visually. It is a small, cube-shaped component, typically black or dark colored, with four or five metal prongs on the bottom that plug into the socket. It looks identical to several other relays in the same box, such as the auto shutdown relay or the blower motor relay, so you need to verify the position carefully using the label or the fuse box diagram.

  4. If the diagram is faded or missing, count the relays in the second fuse box. On the 2008–2010 Commander, the fuel pump relay R7 sits near the fuel pump fuse (fuse #24, rated 20 amps) and the auto shutdown relay R11. The relay is positioned in a row with other system relays, and it is normally the one labeled with a fuel pump symbol.

Important: The 2006–2007 models had a slightly different fuse box layout than the 2008–2010 models. If you own a 2006 or 2007 Commander, the relay location is the same general area, but you should verify the label on the fuse box cover to confirm which relay is the fuel pump relay, because the layout changed starting with the 2008 model year.

What Does the Fuel Pump Relay Do?

Before you start replacing parts, it helps to understand what this relay actually does. The fuel pump relay is an electrical switch that handles the high current required to run the fuel pump. The PCM, which is the vehicle's main computer, sends a small electrical signal to the relay when you turn the ignition to the "ON" position. That signal energizes an electromagnet inside the relay, which pulls a set of contacts closed. Closing the contacts completes the high-current circuit from the battery to the fuel pump, so the pump can build pressure in the fuel lines.

The relay serves two main purposes:

  1. It protects the PCM. The fuel pump draws a significant amount of current, often 10–15 amps or more depending on the load. If that current went directly through the PCM, it could damage the computer. The relay acts as a heavy-duty middleman, letting the PCM send a low-current signal while the relay handles the high-current load.

  2. It provides a safety shutoff. If the engine stalls or the vehicle is involved in a collision, the PCM can de-energize the relay, which cuts power to the fuel pump and stops fuel flow. This is a critical safety feature that reduces the risk of fire after an accident.

The fuel pump relay on the 2008 Commander works in conjunction with the Auto Shut Down (ASD) relay. The ASD relay powers the ignition coils and fuel injectors, while the fuel pump relay powers the pump itself. If either relay fails, the engine will not run. The wiring diagram for the 2008 Commander shows the fuel pump relay receiving power from a fused circuit, with the PCM controlling both the ASD relay and the fuel pump relay through separate control circuits.

Symptoms of a Failing Fuel Pump Relay

A failing fuel pump relay can cause a variety of problems. Recognizing these symptoms early can help you diagnose the issue before you are left stranded.

The most common symptoms include:

  1. The engine cranks but does not start. This is the most classic sign. When you turn the key, the starter motor turns the engine over, but the fuel pump does not run, so no fuel reaches the injectors. The engine will crank indefinitely without firing.

  2. The engine stalls while driving. If the relay has an intermittent fault, the contacts may open and close randomly while the engine is running. When the contacts open, the fuel pump loses power, and the engine dies. The vehicle may restart after a few minutes if the relay cools down or makes contact again.

  3. The engine loses power under load. If the relay is failing internally, it may not pass full voltage to the fuel pump. The pump runs weak, fuel pressure drops, and the engine feels sluggish, especially during acceleration or climbing hills.

  4. No fuel pump prime sound. When you turn the ignition to the "ON" position (without cranking), you should hear a brief hum or buzz from the rear of the vehicle for 2–3 seconds. That is the fuel pump building pressure. If you hear nothing, the pump is not getting power, which points to the relay, a fuse, or the pump itself.

How to Test the Fuel Pump Relay Before Replacing It

Before you buy a new relay, you should confirm that the relay is actually the problem. There are two practical ways to test it: the swap method and the multimeter method.

Method 1: Swap the Relay

This is the easiest and quickest way to test a relay without any special tools.

  1. Locate the fuel pump relay using the steps above.
  2. Find an identical relay in the same fuse box. On the 2008 Commander, common relays that share the same type include the horn relay, the fog lamp relay, or the rear wiper relay. They should have the same part number and the same pin configuration.
  3. Pull out the fuel pump relay and the relay you chose for testing.
  4. Install the fuel pump relay into the socket you pulled the other relay from, and install the known-good relay into the fuel pump relay socket.
  5. Turn the ignition to "ON" and listen for the fuel pump prime sound from the rear of the vehicle.

If the fuel pump now runs, the original relay was faulty and needs to be replaced. If the pump still does not run, the problem lies elsewhere–possibly a blown fuse, a wiring issue, or the fuel pump itself.

A word of caution: When swapping relays, make sure the replacement relay has the same specifications, including the same amperage rating and pin configuration. Using the wrong relay could damage other systems or cause an electrical fire.

Method 2: Test with a Multimeter

If you have a digital multimeter, you can test the relay directly.

  1. Remove the relay from its socket.
  2. Set the multimeter to measure resistance (ohms).
  3. Connect the leads to the relay terminals that correspond to the coil (typically pins 85 and 86 on a standard relay).
  4. Check the reading. A healthy relay coil should read between 50 and 200 ohms. If the reading is outside this range or shows infinite resistance (no continuity), the coil is open, and the relay is bad.
  5. You can also test the switch contacts (typically pins 30 and 87). With the relay unpowered, there should be no continuity between these pins. When you apply 12V to the coil pins, you should hear a click, and the multimeter should show continuity between pins 30 and 87.

Another quick check: With the ignition in the "ON" position, you can place your fingers on the relay and feel for a distinct click when it energizes. If there is no click, the relay is not receiving a signal, or the relay coil is faulty.

How to Replace the Fuel Pump Relay on a 2008 Jeep Commander

Replacing the fuel pump relay is a simple job that most DIYers can handle in about 15–20 minutes. You need only a new relay and basic hand tools.

Here is the step-by-step process:

  1. Disconnect the negative battery terminal. This is a critical safety step. Working on electrical components with the battery connected can cause short circuits, sparks, and potential injury. Use a wrench to loosen the nut on the negative terminal, then slide the cable off and tuck it aside so it does not touch the battery post.

  2. Locate the fuel pump relay. Open the hood and remove the cover from the engine compartment fuse box No. 2. Confirm which relay is the fuel pump relay using the diagram on the underside of the lid.

  3. Pull the old relay out. Most relays simply plug into their sockets. Grasp the relay firmly and pull it straight up. If it is stuck, you can use a pair of needle-nose pliers or a small flathead screwdriver to gently pry it out. Avoid using excessive force, which could damage the socket or surrounding relays.

  4. Inspect the socket. Before installing the new relay, check the socket for corrosion, dirt, or damaged pins. If you see any buildup, clean the contacts with a wire brush or electrical contact cleaner. Damaged or bent pins may require replacing the fuse box or repairing the wiring.

  5. Install the new relay. Align the prongs on the bottom of the new relay with the socket openings. Press down firmly until the relay seats completely. You should feel it click into place.

  6. Reconnect the battery. Reattach the negative terminal and tighten the nut securely.

  7. Test the fuel pump. Turn the ignition to the "ON" position without cranking the engine. You should hear the fuel pump hum for 2–3 seconds as it primes the system. If you hear the pump, the relay is working. Try starting the engine to confirm everything is operational.

How Much Does a Replacement Relay Cost?

The fuel pump relay itself is an inexpensive part, typically costing far less than other fuel system components.

  • Aftermarket relays for the 2008 Commander are available for roughly $14 to $19 at major auto parts retailers. These include brands like Valucraft and Duralast, which offer a limited warranty or a limited-lifetime warranty respectively.
  • OEM Mopar relays are also available. The genuine Mopar fuel pump relay for the Commander carries part number 4727370AA and typically costs around $29. This relay is guaranteed by Mopar's factory warranty and meets the manufacturer's exact specifications.

Given the low cost, replacing a faulty relay is one of the most affordable fuel system repairs you can perform. The labor cost, if you take it to a shop, is typically just the diagnostic time, since the part is cheap and the replacement takes minutes. For most owners, the total cost stays well under $100 even with labor included.

What If the Relay Is Not the Problem?

If you replace the fuel pump relay and the vehicle still will not start, the problem lies elsewhere in the fuel delivery system. Here are the next things to check, in order of likelihood:

1. Check the Fuel Pump Fuse

Before diving into the relay, you should have already checked the fuel pump fuse. On the 2008 Commander, the fuel pump is protected by a 20-amp fuse (fuse #24) in the engine compartment fuse box No. 2. A blown fuse will cause the exact same symptoms as a bad relay: the engine cranks but does not start, and you hear no fuel pump prime.

To check the fuse: Pull fuse #24 and inspect it. The metal filament inside should be intact. If the filament is broken or the glass is discolored, the fuse is blown. Replace it with a new fuse of the same amperage rating. Never replace a fuse with one of a higher amperage, as this can overheat the wiring and cause a fire.

If the new fuse blows immediately, you have a short circuit in the wiring or a failing fuel pump, and you need further diagnostics.

2. Check the Fuel Pump Itself

If power is reaching the fuel pump (confirmed by a working relay and intact fuse), but you still hear no prime sound, the pump may be dead. Fuel pumps on the Commander can fail over time, especially after many years of service. A failing fuel pump may also produce a whining noise, cause intermittent stalling, or reduce fuel pressure under load.

Testing the pump requires a fuel pressure gauge. The pump should deliver a specific pressure range while the engine is running. If the pressure is low or zero, the pump needs replacement.

3. Check the Wiring and Connections

Between the relay, the fuse, and the fuel pump, a wiring harness runs from the engine bay to the fuel tank area. Over time, wires can chafe, corrode, or break, especially in areas exposed to road salt, moisture, or heat.

Inspect the wiring harness for visible damage, and check the connectors at the fuel pump module for corrosion or loose pins. Use a multimeter to test continuity in the circuit. A reading of infinite resistance indicates a break in the wire.

4. Consider the Ignition Switch or PCM

On some vehicles, the ignition switch itself sends the signal that triggers the fuel pump relay. If the ignition switch has worn contacts, the relay may not energize even though it is good. Similarly, a failing PCM may not send the control signal to the relay.

These are more complex diagnostics that typically require a scan tool to read live data and test circuit outputs. If you have ruled out the relay, fuse, wiring, and pump, it may be time to consult a qualified mechanic.

Preventing Future Relay Failures

Fuel pump relays are electrical components, and like all electrical components, they wear out over time. Heat, vibration, and electrical arcing inside the relay all contribute to eventual failure. While there is no way to make a relay last forever, you can take a few steps to reduce the risk of being stranded:

  1. Keep a spare relay in your vehicle. Relays are small and inexpensive. A spare fuel pump relay in your glove box or emergency kit can be a lifesaver if the original fails while you are on the road. The replacement takes minutes, and you can be back on your way without a tow.

  2. Check your fuses and relays periodically. During routine maintenance, such as an oil change or tire rotation, take a minute to inspect the fuse box for signs of corrosion, loose connections, or burnt smells. Early detection of a problem is far cheaper and easier than a roadside breakdown.

  3. Use quality replacement parts. When you do replace a relay, choose a reputable brand. Cheap relays can fail quickly, often within months, and leave you stranded again. OEM Mopar relays or high-quality aftermarket units from trusted brands are worth the small difference in price.

Where to Buy the Fuel Pump Relay

You have two primary options when buying a replacement relay: OEM (Original Equipment Manufacturer) or aftermarket.

OEM Mopar relays are guaranteed to match the factory specifications. The genuine part number for the fuel pump relay on the 2008 Commander is 4727370AA, and it replaces several earlier part numbers including 56006707 and 56006709. OEM parts cost more, but they come with a manufacturer's warranty and are designed specifically for your vehicle.

Aftermarket relays are less expensive and are available from auto parts stores like AutoZone. Popular options include the Duralast Relay 19283, which sells for around $19 and comes with a limited-lifetime warranty, and the Valucraft Relay 19283VC, priced around $14 with a one-year warranty. These relays are designed as drop-in replacements and should work perfectly for most owners.

Whichever route you choose, verify that the relay matches the original specification, including the terminal design (blade connector with five male blades on the Commander) and the system voltage (12V).

The Bottom Line on Your 2008 Jeep Commander Fuel Pump Relay

The fuel pump relay on your 2008 Jeep Commander is a small but critical component located in the engine compartment fuse box No. 2, on the left side of the engine bay. It is labeled R7 on the fuse box diagram, and it sits near a 20-amp fuse that also protects the fuel pump circuit.

When the relay fails, your Commander will crank but not start, stall while driving, or lose power under load. You can test the relay in two ways: swap it with an identical relay from the same fuse box, or use a multimeter to check coil resistance and contact continuity. If the relay is bad, replacement takes about 15 minutes and costs between $14 and $29 for the part.

If a new relay does not fix the problem, check the fuel pump fuse, the wiring, and finally the fuel pump itself. In rare cases, the ignition switch or PCM may be at fault. Always disconnect the battery before working on any electrical components, and if you are ever uncomfortable with a repair, do not hesitate to consult a qualified mechanic.

For many owners, the fuel pump relay is the first point of failure in the fuel delivery system, and it is one of the easiest and cheapest fixes you can perform on your own. Keeping a spare relay in your vehicle is a small investment that can save you from a much bigger headache down the road.

Recommended Upgrade: KEMSO Fuel Pumps

If you discover that your fuel pump itself has failed, not just the relay, consider upgrading to a KEMSO brand fuel pump. KEMSO fuel pumps are high-performance, OEM replacement units designed to deliver reliable fuel flow and precise pressure for your vehicle. Every KEMSO fuel pump is built to meet or exceed original equipment specifications, ensuring a perfect fit and dependable operation for years to come.

What sets KEMSO apart is their commitment to quality and peace of mind. Each fuel pump comes with a lifetime warranty, which means you can install it with confidence and know that KEMSO stands behind their product. Whether you are driving a daily commuter, a weekend off-road rig, or a high-performance machine, KEMSO has a fuel pump that fits your needs.

Visit the KEMSO website today to browse their full lineup of high-performance fuel pumps and find the right one for your vehicle: https://www.kemsoracing.com/


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