1993 Volvo 940 Fuel Pump Relay Location: Your Complete Guide & Fix

The fuel pump relay in your 1993 Volvo 940 is located inside the main relay/fuse box situated under the dashboard on the driver's side. Specifically, it's the large relay socket in the lower right corner (closest to the driver’s seat) when looking at the front panel of the box. It plugs into position number 13 and is typically a standard Bosch-style rectangular relay, likely black. Accessing it requires opening a small panel cover near the hood release lever.

Finding a non-functioning fuel pump relay is a critical first step when your 1993 Volvo 940 cranks but stubbornly refuses to start. Understanding its precise location and how to test or replace it is essential for any DIY owner. This guide provides detailed, step-by-step instructions to locate, identify, access, test, and replace this crucial relay, empowering you to get your 940 running again.

Understanding the Fuel Pump Relay's Role

The fuel pump relay is a vital switch controlled by the engine management system. Its job is simple but critical: it supplies high-current electrical power to the fuel pump located in the tank. When you turn the ignition key to the "ON" position or start cranking, the engine computer sends a small signal to the relay. This signal activates an electromagnet inside the relay, pulling internal contacts together. When these contacts close, they complete the circuit, allowing the significant electrical current required by the fuel pump (typically 5-10 amps) to flow directly from the battery, via the relay, through the relevant fuse, and to the pump itself.

Without this relay functioning correctly, the fuel pump receives no power, leading to a no-start condition and an engine that cranks endlessly without firing. Symptoms pointing directly to a potential fuel pump relay failure include:

  • Engine Cranks But Won't Start: The classic sign. The starter motor spins the engine, but there is no ignition.
  • No Fuel Pump Priming Sound: When you turn the ignition key to "ON" (without cranking), you should hear a distinct humming or buzzing sound from the rear of the car (near the fuel tank) for about 1-2 seconds. This is the pump pressurizing the fuel system. Silence indicates no pump power.
  • Complete Loss of Power During Operation: A failing relay might cut power abruptly while driving, causing the engine to stall instantly without warning.
  • Intermittent Starting Issues: The relay might work only intermittently, sometimes allowing the car to start normally and sometimes not.

Precise Location of the 1993 Volvo 940 Fuel Pump Relay

The central nervous system for electrical circuits, including fuel delivery, is the central relay and fuse box found inside the passenger compartment. Here’s how to locate it and pinpoint the relay:

  1. Position: Sit in the driver's seat. Look towards the lower part of the dashboard, directly below the steering wheel column, just above the pedals. The hood release lever is also located in this area on the driver's side kick panel.
  2. Identify the Box: You will see a rectangular black plastic cover set into the lower dashboard/kick panel trim, positioned vertically. This cover is typically held in place by a plastic thumb screw or a simple clip mechanism at its top.
  3. Access the Cover: Unscrew the thumb screw counter-clockwise or release any clips securing the cover. Carefully pull the cover straight out towards you to remove it. Set it aside safely. You now have direct access to the front face of the fuse/relay box.
  4. Locate the Correct Relay Position: You are looking at the box's faceplate. It will have numerous fuse locations, several larger relay sockets, and often a diagram printed on it (though this diagram may be faded or missing). Focus on the lower right corner of this faceplate. The exact labeling can vary slightly, but the fuel pump relay is universally recognized as the large relay plugged into Position Number 13.
  5. Identifying the Relay: Position 13 is designed for a standard Bosch-style "Type 1" rectangular relay. The relay in your car will likely be:
    • A rectangular black plastic block.
    • Approximately 1 inch wide, 1.5 inches long, and 1 inch high.
    • Has four metal blade terminals on the bottom (usually numbered 30, 85, 86, 87).
    • The Volvo part number is often 352 4055, 351 3057, or similar variants (Bosch common numbers include 0 332 014 135 and 0332014135). Look for numbers stamped on the relay housing.
    • Key Tip: When you locate a relay in Position 13, gently grasp it. If your car has the original or correct relay, you should feel an embossed "13" directly on the top of the relay housing. This is the most reliable visual confirmation. A common mistake is confusing it with the large fuel injection relay often found nearby (which handles injectors and sensors, not the pump itself).

(Imagine Photo 1: Wide shot showing the driver's footwell area, highlighting the fuse/relay box cover location below the steering wheel.)
(Imagine Photo 2: Close-up of the fuse/relay box faceplate with the cover removed. A red circle clearly highlights Position 13 in the lower right corner.)
(Imagine Photo 3: Close-up of a typical Bosch-style relay clearly embossed with the number "13" on its top.)

Accessing and Removing the Relay

With the fuse box cover removed and the relay identified, follow these steps to remove it for inspection or replacement:

  1. Ensure Safety: Turn the ignition key completely OFF. Remove the key from the ignition switch. It's also prudent to disconnect the negative (-) terminal of your car's battery as an extra safety measure. Use the correct size wrench (typically 10mm) to loosen the clamp bolt. Move the cable terminal away from the battery post.
  2. Relay Removal: Face the fuse box squarely. Grasp the identified fuel pump relay firmly by its sides. Apply steady, straight pulling force directly outwards (towards you). Avoid excessive wiggling or twisting, as this can damage the relay socket pins or the relay itself. The relay should slide out relatively easily from its socket due to the friction fit of the blade terminals.
  3. Inspect: Examine the relay. Check for any obvious signs of damage: melted plastic, cracking, burnt smell, or corrosion on the metal blade terminals.

(Imagine Photo 4: Hand grasping a relay firmly at its sides, about to pull straight out.)
(Imagine Photo 5: Relay being removed from its socket, showing the four blade terminals.)

Testing the Fuel Pump Relay

You suspect the relay is faulty. Testing confirms it. Two primary methods exist:

Method 1: Listen and Feel (Simple Function Test)

  1. Carefully re-insert the suspected relay back into socket 13. Ensure it's seated firmly and correctly. Do not reconnect the battery negative cable yet.
  2. Listen: Have a helper stand near the rear of the car (near the fuel filler door area). Ensure the car is in Park or Neutral with the parking brake firmly applied. Turn the ignition key to "ON" (don't crank!). Your helper should listen intently for the distinct, audible humming or buzzing sound of the fuel pump priming for 1-2 seconds.
  3. Feel: Simultaneously, you can place your fingers directly on the relay body. If the relay is functioning correctly, you should feel a faint but distinct click inside the relay as soon as the key is turned to "ON". This click is the sound of the internal contacts closing.
  4. Interpretation: If you hear the pump prime and feel the relay click, the relay is likely functioning correctly at that moment. If there's no audible pump prime and no relay click, it strongly indicates a problem with the relay, the fuse powering it, the signal from the computer, or the pump circuit itself. A click without the pump sound points to a problem downstream of the relay (blown fuse, wiring fault, pump failure). No click almost always points to a relay failure or an issue with the control signal.

Method 2: Relay Bench Testing (Using a Multimeter)

This requires a digital multimeter capable of measuring continuity or resistance (Ohms Ω).

  1. Identify Terminals: Look at the bottom of the relay where the four blade terminals are. They are usually molded into the plastic base with tiny numbers: 85, 86, 30, 87.
    • 85 & 86: These are the coil terminals (the "switch" that activates the relay). Applying 12V across these terminals creates an electromagnetic field that pulls the internal switch contacts together.
    • 30: Common terminal. This connects to the power source (battery positive via fuse).
    • 87: Normally Open (NO) terminal. When the relay coil (85/86) is NOT energized, there is NO connection between 30 and 87. When the coil IS energized, 30 and 87 become connected.
  2. Test the Coil (85 & 86): Set your multimeter to the resistance (Ohms Ω) setting. Place one probe on terminal 85 and the other on terminal 86. A good relay coil will show a specific resistance reading, typically between 50 and 150 Ohms. If you see:
    • Continuity (0 Ohms or very low Ohms): The coil is shorted internally (bad relay).
    • Infinite Resistance (OL - Open Line): The coil is broken/open internally (bad relay).
    • Reading within 50-150 Ohms: Coil is likely good. Proceed to test the switch contacts.
  3. Test the Switch Contacts (30 & 87): Set your multimeter to continuity mode (often symbolized by a diode icon or sound wave icon). Place one probe on terminal 30 and the other on terminal 87.
    • Continuity Detected: This indicates the switch contacts are welded or stuck CLOSED (bad relay - dangerous as pump might run constantly).
    • No Continuity: This is CORRECT for the unpowered state (relay de-energized). Now, you need to test if the contacts close when the coil is powered.
  4. Test Contact Operation: You will need a separate source of 12 Volts. A small 9V or 12V battery works best (like a small hobby battery or even a 9V smoke detector battery - though it may not reliably pull the contacts together if weak; a full 12V motorcycle/car battery is ideal). Alternatively, you can use jumper wires connected to your car battery with the car ignition OFF.
    • Connect the POSITIVE (+) lead from your 12V power source to relay terminal 86.
    • Connect the NEGATIVE (-) lead from your 12V power source to relay terminal 85.
    • Your multimeter probes should still be on terminal 30 and 87.
    • With power applied to the coil (85 & 86), you should hear/feel an audible CLICK, and your multimeter should now show CONTINUITY between terminals 30 and 87.
  5. Interpretation: If the coil reads correctly (50-150Ω) and the switch contacts correctly show NO CONTINUITY without power and CONTINUITY when 12V is applied to the coil (85 & 86), the relay is functional. If either the coil test or the contact switching test fails, the relay is defective and needs replacement.

(Imagine Photo 6: Close-up of relay bottom, clearly showing blade terminal numbers 30, 85, 86, 87.)
(Imagine Photo 7: Multimeter probes testing resistance between terminals 85 & 86 - showing ~80 Ohms reading.)
(Imagine Photo 8: Multimeter probes testing continuity between terminals 30 & 87 - showing "OL" (no continuity).)
(Imagine Photo 9: Jumper wires from a 12V battery connected to terminals 86 (+) and 85 (-), with multimeter probes on 30 & 87 - showing "0.00" or similar continuity reading and hearing the relay click.)

Replacing the Fuel Pump Relay in Your 1993 Volvo 940

If testing confirms a faulty relay, replacement is straightforward:

  1. Obtain the Correct Replacement: Crucial! Match the replacement relay precisely.
    • Best Option: Purchase a relay specifically labeled for the 1993 Volvo 940 fuel pump. Mention the Volvo Part Number (e.g., 352 4055 or 351 3057) and/or the Bosch Part Number (0 332 014 135) to the parts supplier. OEM or OEM-spec relays are recommended. Reputable auto parts stores (O'Reilly, AutoZone, NAPA, Advance Auto Parts, RockAuto) can cross-reference these numbers.
    • Verify: Physically compare your old relay to the new one. They should be identical in size, shape, and terminal pattern. They should both be designed for position 13. Ensure the new one has the "13" embossed on top or is clearly labeled for the fuel pump relay for your specific 940 model year. Avoid generic relays unless you have verified the terminal functions perfectly match.
  2. Prepare: Turn the ignition OFF and remove the key. Disconnect the negative battery terminal (10mm wrench).
  3. Access: Remove the fuse/relay box cover under the driver's dash as described earlier.
  4. Remove the Old Relay: Grasp the faulty relay firmly by its sides and pull it straight out of socket position 13. Set it aside.
  5. Install the New Relay: Orient the new relay so that its terminals match the socket pins. Align it carefully and press it firmly and squarely into socket 13 until it is fully seated. You should feel and hear it click into place. Avoid forcing it. Ensure the embossed "13" (if present) is facing upwards.
  6. Reconnect: Reattach the negative battery cable terminal to the battery post and tighten the clamp bolt securely.
  7. Test Function: Turn the ignition key to "ON" (do not start). You should immediately hear the distinct 1-2 second hum of the fuel pump priming from the rear of the car. Feel the relay – you should feel a faint click as it activates.
  8. Start the Car: Crank the engine. If the relay was the only issue, the engine should start normally.
  9. Finalize: Replace the fuse/relay box cover. Secure its screw or clip.

Common Mistakes and Important Considerations

  • Confusing Relays: Mismatching the relay positions is the single most common mistake. Ensure you are removing/replacing ONLY the relay from position 13. The large "fuel injection relay" is often adjacent (usually position 15 or similar) and controls the injectors and sensors; using it in place of the fuel pump relay won't work, and vice-versa.
  • Fuse Check: ALWAYS inspect the relevant fuses before and after dealing with the relay. The fuel pump circuit usually relies on a fuse located in the main fusebox or sometimes in the under-hood fuse box. Check your owner's manual or the diagram printed on the fuse box cover to identify the Fuel Pump Fuse (often a 15A fuse). A blown fuse will cause identical symptoms to a bad relay and could be the root cause, or it could blow because of a failing relay or pump motor.
  • Safety First: Always disconnect the battery negative terminal before removing or inserting relays to prevent accidental short circuits or electrical spikes. Wear safety glasses when working under the dash.
  • Tool Safety: When testing with jumper wires near the battery or relay socket, be extremely careful to avoid touching both relay terminals simultaneously with one tool and causing a short circuit. Keep metal tools away from exposed electrical contacts.
  • Beware of Cheap Relays: Low-cost, generic relays sold online or in discount stores can be unreliable out of the box or fail prematurely. Investing in a quality brand (Bosch, OEM, or high-reputation aftermarket like Hella or Standard Motor Products) is worthwhile for this critical component.
  • Corrosion: If you live in a humid or salty environment, check the relay socket and relay terminals for signs of corrosion (green/white powdery buildup). Clean carefully with electrical contact cleaner and a small wire brush if needed. Ensure the battery terminals are also clean and tight.
  • Beyond the Relay: If replacing the relay (and confirming the fuse is good) still does not fix the no-start/no-pump issue, the problem lies elsewhere. Potential causes include:
    • Bad Fuel Pump: The pump itself has failed.
    • Wiring Fault: Broken, frayed, or disconnected wire between the fuse box and the fuel pump, or in the signal circuit from the computer to the relay.
    • Faulty Inertia Switch: Most Volvos have a crash safety switch ("inertia switch" or "fuel cut-off switch") usually located in the trunk or rear passenger compartment. This switch cuts power to the fuel pump in the event of a collision. Sometimes, a minor bump or electrical glitch can cause it to trip. Locate and reset it (press a button on top). Verify its wiring.
    • Ignition Switch Failure: A faulty ignition switch might not be sending the signal to the computer to activate the relay.
    • Computer (ECU) Failure: Less common, but a fault in the engine control unit itself could prevent it from activating the relay.
  • Check Connectors: Verify the multi-pin connector on the fuel pump access cover (under the rear seat bench cushion) is clean and tight. Also, inspect the main harness connections near the computer.

Troubleshooting When the Car Still Won't Start (After Relay Replacement)

If replacing the confirmed bad relay doesn't fix the problem:

  1. Verify Fuel Pump Sound: Re-test with ignition "ON" – Do you hear the pump prime?
    • YES (Pump Runs): The relay is working and power is reaching the pump. The problem is likely NOT fuel delivery anymore. Shift focus to ignition system (spark plugs, wires, distributor cap, rotor, ignition coil, ignition control module) or severe fuel pressure issues (clogged filter, failing pump pressure regulator).
    • NO (Pump Silent): Power is still not reaching the pump. Proceed.
  2. Recheck Fuse: Check the Fuel Pump Fuse again. Did it blow instantly? If yes, there is likely a short circuit in the fuel pump circuit or a failing pump motor drawing excessive current.
  3. Test Power at Relay Socket:
    • Locate the Fuel Pump Relay Socket (Position 13).
    • Set multimeter to Volts DC. Connect the negative (black) probe to a good ground point (bare metal under dash or battery negative terminal).
    • With ignition key OFF, probe terminal 30 in the empty socket. You should see constant Battery Voltage (~12V).
    • With ignition key turned to "ON", probe terminal 87 in the empty socket. You should see Battery Voltage for 1-2 seconds. This confirms power output from the socket when the relay should be engaged.
  4. Test Relay Control Signal:
    • Set multimeter to Volts DC.
    • Probe terminal 85 in the empty socket. Connect black probe to ground.
    • Turn ignition key to "ON". You should see a brief pulse of voltage (~12V) for 1-2 seconds. This signal comes from the computer. If you see this, the computer is commanding the relay ON.
    • If NO voltage appears on terminal 85 during ignition ON, the problem is upstream: bad wire from computer, faulty ignition switch, or faulty computer.
  5. Test Power at the Pump:
    • Gain access to the fuel pump electrical connector (located under the rear seat bench cushion, under a plastic access cover).
    • Disconnect the pump connector.
    • Set multimeter to Volts DC. Connect the black probe to a good ground point at the rear of the car (bare metal chassis).
    • Connect the red probe to the wire in the car's harness connector that is designed to carry Positive Power to the pump (usually a thicker wire, often red or red/white - consult wiring diagram for certainty if unsure).
    • Have an assistant turn the ignition key to "ON". You should see battery voltage at this wire for 1-2 seconds. If you do, but the pump doesn't run, the pump is faulty. If you do NOT see voltage at this wire, you have a wiring fault or blown fuse after the relay socket.

Conclusion

Knowing the precise 1993 Volvo 940 fuel pump relay location (Position 13 in the driver's footwell fuse/relay box) is fundamental knowledge for tackling a common and frustrating no-start condition. By carefully following the steps to locate, identify, test, and replace this relay, you possess a cost-effective solution that can save a tow truck call and significant repair costs. Always prioritize safety by disconnecting the battery, double-check the relay position and fuse status, and invest in a quality replacement part. If issues persist beyond the relay, systematic troubleshooting of power signals and the pump itself will get to the root of the problem. Mastering this repair empowers every 940 owner to keep their cherished Swedish classic reliably on the road.

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