The Complete Guide to Your 2012 Jeep Grand Cherokee Fuel Pump Relay: Symptoms, Location, Testing & Replacement

If your 2012 Jeep Grand Cherokee cranks but refuses to start, a failed fuel pump relay is a highly probable culprit and often the most affordable fix to get you back on the road. This critical electrical component acts as the gateway switch for your fuel pump. When it malfunctions, power cannot reach the pump, meaning fuel isn't delivered to the engine. Understanding the role, signs of failure, exact location, testing procedures, and replacement steps for the fuel pump relay in your specific 2012 Grand Cherokee is essential knowledge for diagnosing frustrating no-start conditions and preventing costly misdiagnoses of the fuel pump itself.

Why the Fuel Pump Relay is Non-Negotiable in Your Jeep's Operation

Every modern vehicle, including the 2012 Jeep Grand Cherokee, relies on relays to control high-current electrical components like the fuel pump. The fuel pump draws significant electrical power to generate the high pressure needed for fuel injection. Running this power directly through the ignition switch and standard wiring would cause excessive voltage drop, premature switch failure, and potential fire hazards.

This is where the relay comes in. It's essentially an electrically operated switch. A small control current from the Jeep's Powertrain Control Module (PCM) energizes the relay's electromagnet coil. This magnetism pulls internal contacts together, closing a separate, heavy-duty circuit that delivers the full battery power directly to the fuel pump motor. When you turn the key to the "Run" position before cranking, the PCM briefly energizes the fuel pump relay for a few seconds to prime the fuel system. When you crank and run the engine, the PCM keeps the relay energized continuously. If the relay fails, the fuel pump won't run at all, no matter how perfect the pump itself might be. Relays are wear items; over time and numerous cycles, their internal contacts can pit, corrode, weld shut, or become intermittent. The electrical coil can also fail.

Classic Symptoms of a Failing or Failed Fuel Pump Relay in Your 2012 Grand Cherokee

Recognizing the symptoms can save you significant diagnostic time and expense. The most common signs directly linked to a problematic fuel pump relay include:

  1. Engine Cranks But Won't Start: This is the hallmark symptom. The starter motor spins the engine normally, but it fails to fire up and run. You don't hear the brief whirring of the fuel pump when you turn the key to "Run" before cranking. The engine lacks fuel.
  2. Sudden Engine Stall While Driving: A relay failing intermittently or suddenly can cause the engine to cut out completely while driving, often without warning. The fuel pump instantly loses power.
  3. Intermittent Starting Problems: Your 2012 Grand Cherokee may start perfectly one day, then refuse to start the next, only to start again later. This randomness strongly suggests an electrical connection issue like a failing relay with sticky or corroded contacts. Hot engine bay temperatures can exacerbate the issue.
  4. Silent Fuel Pump: When you turn the ignition key to the "ON" position (without cranking), you should clearly hear a distinct humming or whirring sound lasting 2-3 seconds coming from the rear of the vehicle (the fuel tank area). This is the fuel pump priming the system. If you consistently hear nothing, the fuel pump isn't being activated. While it could be a bad pump, the relay is statistically the more likely and much cheaper first suspect.
  5. No Power to Fuel Pump: Confirmed with a multimeter test at the fuel pump electrical connector. This points directly to the circuit feeding the pump – relay, fuses, or wiring. Start with the relay and fuse checks.

Crucial Tip - Avoid Premature Fuel Pump Replacement: Experiencing a "cranks but no start" and lacking fuel pump noise leads many owners and less-experienced mechanics to immediately condemn the fuel pump. Replacing a fuel pump in a Grand Cherokee is labor-intensive and expensive. Always check the relay (and associated fuse) first. It's significantly less expensive and takes minutes compared to hours dropping the tank.

Pinpointing the Relay Location in the 2012 Grand Cherokee TIPM

The location of the fuel pump relay in the 2012 Jeep Grand Cherokee is crucial for diagnosis and repair. Unlike many vehicles where relays might be found in separate fuse boxes under the hood or dashboard, Jeep integrates relays and fuses into a central module:

  • Module Name: TIPM (Totally Integrated Power Module).
  • Location: Under the hood, driver's side. It's the large, black, rectangular box positioned near the firewall and the battery.
  • Relay Position: The fuel pump relay is located within the internal grid of the TIPM. Crucially, its position depends on the build date of your specific 2012 Grand Cherokee. Jeep made changes to the TIPM layout mid-2012.
    • For vehicles built BEFORE approximately July 2011 (Early Build Dates): The fuel pump relay is commonly found in Position K7 of the TIPM relay grid. This is generally the fourth relay position from the front (radiator side), second row from the top. Always verify using the printed cover diagram on your TIPM!
    • For vehicles built AFTER approximately July 2011 (Late Build Dates): The fuel pump relay is typically found in Position K51 (often labeled in diagrams as "FP MTR") within the TIPM relay grid. Position K51 is usually located in the third row down, potentially the 7th or 8th relay position from the front. This location is shared with the Engine Control Module (ECM) Power Relay, which sometimes uses the same relay part number.
  • How to Locate (Safely):
    1. Ensure the ignition is OFF.
    2. Open the hood.
    3. Locate the black TIPM box near the driver's side firewall/battery.
    4. Carefully unclip and remove the large plastic protective cover of the TIPM.
    5. Look on the underside of the cover you just removed. There should be a printed diagram mapping the fuse and relay positions. This is your authoritative guide. Never guess!
    6. Locate the relay labeled "Fuel Pump" or "FP MTR" (Fuel Pump Motor) or "K7" / "K51" based on the diagram specific to your VIN/build date. The relay in question is a standard International (ISO) micro/mini-relay (about 1 inch square).
    7. Note the position clearly before proceeding.

Relay Identification and the Critical Role of the ASD Relay

The fuel pump relay in the 2012 Grand Cherokee is almost always a standard ISO micro/mini-relay. Common factory part numbers include 56027866AB, 56027866AE, or similar successors. Aftermarket equivalents like Ry551 or Tyco VF7-11Z99-R1 or Standard RY511 are readily available.

  • Physical Characteristics: Black plastic housing, square (approx. 1" x 1" base), typically with five small blade terminals on the bottom. The key identifying feature is its location in the TIPM, labeled by the diagram.

The ASD Relay Intertwined Operation

A crucial point often overlooked is the relationship between the Fuel Pump Relay and the Automatic Shutdown (ASD) Relay. On 2012 Grand Cherokees (especially those with the K51 Fuel Pump Relay setup), the fuel pump circuit is often controlled through the ASD relay circuit.

  1. Sequence: When you turn the key to RUN or START, the PCM first energizes the ASD Relay.
  2. Dependency: Once the ASD relay closes and sends power, this often provides the necessary path for the PCM to then energize the Fuel Pump Relay. Power from the ASD relay circuit feeds the Fuel Pump Relay coil.
  3. Consequence: If the ASD Relay fails, it will prevent the Fuel Pump Relay from ever receiving its "turn on" signal from the PCM, even if the fuel pump relay itself is perfectly good. This means:
    • A failed ASD Relay can cause identical symptoms to a failed Fuel Pump Relay (crank/no start, no fuel pump noise).
    • Testing the ASD Relay is just as critical as testing the Fuel Pump Relay when diagnosing a no-start condition. The ASD relay is usually located nearby in the TIPM (refer to your cover diagram - often labeled "ASD"). They often use the exact same part number relay.
    • Recommendation: When replacing the Fuel Pump Relay, it is prudent practice to replace the ASD Relay simultaneously. They endure similar electrical loads and thermal cycles and are similarly priced. This prevents an almost identical failure shortly down the road and simplifies diagnostics.

Testing the 2012 Grand Cherokee Fuel Pump Relay - DIY Steps

Testing the relay is straightforward and requires minimal tools. You need:

  • A multimeter (digital preferred, set to Ohms for resistance testing and Volts DC for power testing).
  • Access to the relay in the TIPM.
  • Basic hand tools to carefully remove the relay (fingers are usually sufficient, but needle-nose pliers may help gently grip it).

Two Main Testing Methods:

Method 1: Listening / Feeling Test (Simple but Not Definitive)

  1. Have a helper turn the ignition key to the "ON" (RUN) position (do not crank).
  2. You should hear a distinct click from the TIPM area and simultaneously feel the relay physically "click" under your fingers as its contacts close and energize the fuel pump.
  3. After a few seconds, you should hear another click as the relay de-energizes (if engine isn't cranking/running).
  4. No click: This strongly suggests the relay or its control circuit (fuse, PCM signal) is faulty. Proceed to Method 2. Important: Hearing a click only confirms the relay's electromagnet coil activated; it does not guarantee the internal high-current contacts are actually passing power correctly. They could be burned or corroded.

Method 2: Voltage & Continuity Testing (More Reliable)

Always refer to your specific TIPM cover diagram to identify the relay socket terminals.

A. Testing Relay Coil Circuit (Terminals 85 & 86):

  1. Remove the fuel pump relay from its socket in the TIPM.
  2. Set multimeter to Ohms (Ω).
  3. Touch probes to terminals 85 and 86 of the relay (consult diagram or relay base; these are typically the coil control pins). This checks the coil's resistance.
  4. Reading: You should get a resistance value typically between 50Ω to 120Ω. An open circuit (OL or infinite resistance) means the coil inside the relay is burnt out. A very low or zero reading indicates an internal short. Both mean replace the relay.
  5. (Optional Power Test): Place relay aside. Turn ignition key to ON. Use multimeter set to Volts DC. Touch black probe to ground (battery negative terminal is safe and reliable). Touch red probe to Terminal 86 in the now-empty relay socket. You should see battery voltage (approx. 12V). Touch red probe to Terminal 85. You should see a ground signal (0V) or a low-voltage control signal from the PCM. If you DON'T see the expected battery voltage on the socket's Terminal 86 with the key ON, check the relevant fuse feeding that circuit (often Fuse F04 - 20A or F27 - 20A in TIPM - CHECK YOUR DIAGRAM!). If you do see battery voltage at 86 and a good ground at 85 but the relay coil didn't measure good (step 3-4), the relay is definitively bad.

B. Testing High-Current Contact Circuit (Terminals 30 & 87):

  1. Set multimeter to Ohms (Ω).
  2. Place multimeter probes on terminals 30 and 87 of the removed relay. This tests the contacts that switch power to the pump.
  3. Initial Reading: Should show "OL" (Open Line) or Infinite Resistance. This is normal when the relay is de-energized.
  4. Testing Contact Closure: Connect a fused jumper wire (or a simple piece of wire - CAREFULLY) between terminal 86 (+) and terminal 85 (-) of the relay. You should hear and feel an audible CLICK. While applying power to 85/86, measure resistance again between 30 and 87.
  5. Reading: Should now show very low resistance (near 0Ω). If it remains open (OL) or shows very high resistance with power applied to the coil, the relay's internal contacts are faulty. Replace it.

C. Testing Socket Output Voltage (Terminals 30 & 87):

  1. Reinsert the relay into its socket in the TIPM (ensure it's fully seated).
  2. With ignition key turned to ON, use multimeter on Volts DC.
  3. Carefully backprobe the wire at the socket terminal for 87 (the output to the fuel pump). Warning: Ensure probes don't short.
  4. Black probe on ground. With key ON, you should see battery voltage (approx. 12V) for 2-3 seconds at Terminal 87 in the socket. If you don't see voltage here, the relay isn't switching power OR it's not getting power. Go back to steps A and B.
  5. Confirm constant battery voltage at Terminal 30 in the socket (this is the fused power input to the relay contacts). Test with key ON. If no voltage at Terminal 30, trace back to its fuse.

Replacing the Fuel Pump Relay in Your 2012 Grand Cherokee

Replacement is often the simplest part of this process, assuming you've confirmed location and testing points to the relay.

  • Part Needed: Obtain the correct replacement. Either the Mopar OEM Part (e.g., 56027866AE, 68070007AA, confirm supersession) or a high-quality aftermarket ISO Micro Relay with the exact same pinout specifications (e.g., TYCO VF7, Standard RY511, Bosch 0 332 019 150, Denso 056700-7301, RY551). Recommendation: Stick with known quality brands (TYCO/Te Connectivity, Bosch, Denso, Standard Motor Products) to avoid premature failure of cheap clones.
  • Replace the ASD Relay Too: As mentioned, this relay is critical and often identical to the Fuel Pump Relay. Replace it simultaneously as preventative maintenance.
  • Procedure:
    1. Ensure ignition is OFF. Remove Key.
    2. Open Hood. Locate TIPM. Remove its plastic cover.
    3. Locate the fuel pump relay (and ASD relay if replacing) using the printed diagram on the cover. Identify the exact position(s) clearly.
    4. Gently grasp the faulty relay firmly with your fingers or a pair of needle-nose pliers. Pull it straight up and out of its socket. Don't wiggle excessively.
    5. Take your new relay and align it carefully over the empty socket. Ensure the terminal pattern matches precisely. Relays are keyed to prevent reverse installation, but double-check.
    6. Press down firmly until the relay is fully seated in the socket.
    7. Repeat for the ASD relay if replacing it.
    8. Reinstall the TIPM cover securely.
  • Final Check: Turn the ignition key to ON. Listen for the distinct 2-3 second fuel pump priming sound near the rear of the vehicle. If heard, try starting the engine.

Preventative Maintenance and Troubleshooting Tips

  • Relay Life: Relays don't last forever. If your 2012 Grand Cherokee has high mileage (over 150,000 miles) or you frequently experience short-trip driving, the relay operates more frequently and ages faster. Consider preventative replacement of both the fuel pump and ASD relays around 100,000-120,000 miles.
  • Carry a Spare: Due to their critical nature and low cost, keep a spare fuel pump/ASD relay in your glove box along with the necessary fuse puller/installation tool that often comes in the fuse box kit. This can be a lifesaver away from home.
  • Check Associated Fuses: Always inspect the fuse directly supplying power to the fuel pump relay (Terminal 30) and the fuse supplying the control circuit for the relay coil (likely supplying Terminal 86). In the TIPM, common suspects include Fuse F04 (20A), Fuse F27 (20A), Fuse F28 (20A), or even others depending on the exact TIPM configuration. YOUR COVER DIAGRAM IS LAW. The PCM Power Fuse can also interrupt relay control signals.
  • Wiring Checks: If relay testing passes but the problem persists, inspect wiring between the TIPM and the fuel pump connector in the rear (especially near areas prone to chafing or damage). Also check grounding points.
  • PCM Issues (Rare): A very rare cause can be a failure within the PCM itself failing to trigger the relay coil circuit. Rule out everything else (relays, fuses, wiring) first.

When the Relay Isn't the Problem (Next Steps)

If you replace the relay (and ASD relay), check all relevant fuses, and still have no fuel pump operation or the engine cranks but won't start:

  1. Verify Power at Fuel Pump Connector: Access the fuel pump connector near the top of the fuel tank (under the vehicle). With key turned to ON (and then cranking), test for battery voltage at the connector. No voltage: Problem remains in the wiring/relays/fuses between the TIPM and pump (keep tracing). Full voltage: The problem is likely the fuel pump itself, or its ground circuit.
  2. Test Fuel Pump Ground: Use the multimeter to ensure the pump's ground terminal has continuity to chassis ground. If ground is good and 12V+ reaches the pump connector but the pump doesn't run, the pump motor is faulty.
  3. Consider Fuel Pressure Test: Using a fuel pressure gauge on the fuel rail schrader valve confirms if the pump is delivering adequate pressure, even if it runs. Low pressure could indicate a failing pump, clogged filter, or pressure regulator issue. Lack of pressure confirms a fuel delivery failure.

Understanding the Critical Role: Fixing the No-Start Problem Efficiently

Diagnosing and replacing the fuel pump relay (and often the ASD relay) in your 2012 Jeep Grand Cherokee is a foundational skill for solving the common and frustrating "cranks but won't start" problem. By understanding the relay's function, knowing its exact location within the specific TIPM configuration for your model year and build date, performing simple electrical tests, and using the correct replacement parts, you can resolve this issue quickly and cost-effectively. Always prioritize safety – disconnect the battery if accessing connectors beyond the relay socket. Use the TIPM cover diagram as your guide, check the ASD relay simultaneously, and avoid the costly mistake of prematurely replacing the fuel pump by thoroughly checking these small but vital electrical switches first. Taking these steps empowers you to keep your Grand Cherokee reliably on the road.

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