1992 Dodge D150 Fuel Pump Relay: Location, Symptoms, Testing & Replacement Guide

Replacing a faulty fuel pump relay is often the fastest and most economical solution to no-start or engine stalling problems in your 1992 Dodge D150. Located near the battery, this small, inexpensive electrical component acts as a switch, controlling power to the vital electric fuel pump inside the gas tank. When it fails, fuel delivery stops, leaving your truck stranded. Understanding its role, recognizing failure signs, knowing its location, and being able to test or replace it yourself can save significant time and money.

Why the Fuel Pump Relay is Critical for Your D150's Operation

The 1992 Dodge D150 uses an electric fuel pump submerged in the fuel tank. This pump generates the high pressure (typically around 55-62 PSI for the fuel injection system) required to deliver fuel to the engine. However, constantly running the pump at full battery voltage would be inefficient and potentially unsafe. The fuel pump relay solves this. It receives a low-current signal from the engine computer or ignition switch. Upon receiving this signal, the relay's internal electromagnet closes a set of high-current contacts. This completes the circuit, sending full battery power directly to the fuel pump motor. When you turn the key off, the signal stops, the relay opens, and the fuel pump shuts down. A malfunctioning relay interrupts this essential power supply chain.

Common Symptoms of a Failing 1992 Dodge D150 Fuel Pump Relay

Spotting a failing relay early prevents inconvenient breakdowns. Watch for these telltale signs:

1. Engine Cranks But Won't Start: This is the most classic symptom. If the engine turns over normally with the starter but refuses to fire up, and you cannot hear the fuel pump buzz for a few seconds when you first turn the ignition key to "ON" (before cranking), the relay (or the pump itself, or related wiring/fuses) is a prime suspect.
2. Engine Stalls Suddenly While Driving: An intermittent relay failure can cause the engine to die abruptly without warning while driving, as if the ignition was turned off. It might restart immediately, or after cooling down, or not at all.
3. Intermittent Starting Problems: The truck might start fine one time, then refuse to start the next, exhibiting symptoms sporadically. This erratic behavior is common with relays whose internal contacts are worn, corroded, or cracked, making inconsistent electrical connections.
4. No Fuel Pump Prime Sound: When you turn the ignition key to the "ON" position (without cranking the engine), you should distinctly hear a brief whirring or humming noise (lasting 1-3 seconds) from the rear of the truck near the fuel tank. This is the fuel pump pressurizing the system. Silence points strongly to a problem in the pump circuit – relay, fuse, wiring, or pump.
5. Clicking Sound from the Relay Area: Sometimes, a completely failed relay or one with a weak internal coil might emit a rapid clicking sound when the ignition is turned on. This indicates the relay is trying to engage but failing to hold the contacts closed properly.

Precise Location of the Fuel Pump Relay in a 1992 Dodge D150

Finding the relay is straightforward. It resides within the Power Distribution Center (PDC), a rectangular black plastic box located on the driver's side fender well, immediately next to the battery. This box houses several important fuses and relays.

1. Open the PDC Lid: Release the latches or unscrew the fasteners holding the lid on top of the black plastic box next to the battery.
2. Locate the Relay Bank: Inside, you'll see a row or array of cube-shaped relays plugged into sockets. Each relay socket should have an identifying label molded into the plastic inside the PDC lid.
3. Identify the Correct Relay: Look specifically for the relay labeled "FUEL PUMP" or "AUTO SHUTDOWN (ASD)". Crucially, in the 1992 Dodge D150, the fuel pump relay is part of the ASD relay circuit. This single relay often controls both the fuel pump and the ignition system's Auto Shutdown functions. Therefore, the relay typically labeled "ASD" is the one controlling the fuel pump. The lid diagram is your definitive guide. Relays themselves are usually marked with a part number (commonly MB213189 or equivalent) but might not indicate function on the relay body.

Testing the 1992 Dodge D150 Fuel Pump Relay (Two Methods)

Verifying relay function requires a basic multimeter and sometimes a helper.

Method 1: The Swap Test (Simple Check)
The PDC contains multiple identical relays (like the horn relay, AC clutch relay, etc.). Find a relay of the exact same part number in another socket that controls a non-essential function (e.g., horn).

1. Identify Swap Candidate: Refer to the PDC lid diagram to find another relay with the same part number (e.g., the horn relay).
2. Swap: Carefully pull out the suspected bad ASD/Fuel Pump relay and plug it into the known good socket (e.g., Horn). Plug the known good relay into the ASD/Fuel Pump socket.
3. Test Function:
   • If the previously non-working horn now works with the old ASD relay plugged in, then the old ASD relay is faulty.
   • Turn the ignition key to "ON." Listen for the fuel pump prime sound. If you now hear the pump run with the known good relay in the ASD socket, then the original ASD relay was indeed faulty. If you still don't hear the pump, the problem lies elsewhere (fuse, wiring, pump, etc.).

Method 2: Bench Testing with a Multimeter
This requires a digital multimeter (DMM) set to measure resistance (Ohms).

1. Remove Relay: Pull the suspected fuel pump (ASD) relay from its socket.
2. Identify Terminals: Examine the bottom. There are 4 or 5 blade terminals. Common pinouts (check your relay markings/datasheet):
   • Control Circuit: Two terminals connect to the relay's internal coil (e.g., terminals "85" & "86").
   • Load Circuit: Two terminals are the main high-current switch contacts (e.g., terminals "30" - Common Power In, "87" - Switched Power Out). Some relays may have a fifth pin ("87a"), unused in this application.
3. Test Coil Resistance:
   • Set the DMM to Ohms (Ω).
   • Place probes on the two coil terminals (e.g., 85 & 86).
   • A reading within specification is needed. Look for a value printed on the relay body (e.g., "50-120 Ω" is common). A reading of "OL" (Overload/Open) or significantly outside the expected range indicates a bad coil.
4. Test Contact Resistance (Switched Circuit):
   • Place DMM probes on the high-current switch contact terminals (e.g., "30" & "87"). Ensure you are not touching the coil terminals.
   • The DMM should read "OL" (infinite resistance, open circuit). This shows the contacts are open when the relay is not energized.
   • Apply 12 volts to the coil terminals! Use fused jumper wires from the battery positive terminal to terminal "86" and negative to terminal "85". Hear and feel the relay click closed. Keep the test voltage applied.
   • With the coil energized, re-measure resistance between the high-current terminals (e.g., "30" & "87"). It should read near 0 Ohms (a short circuit). If it still shows "OL" or high resistance, the internal contacts are burned out or corroded, indicating a bad relay.

Replacing the 1992 Dodge D150 Fuel Pump Relay (ASD Relay)

Replacement is simple once the faulty relay is identified:

1. Purchase Correct Replacement: Buy the exact relay specified for the 1992 D150's ASD/Fuel Pump circuit. An exact physical match (same pin configuration) and electrical ratings are essential. Common OEM part numbers include MB213189. Excellent aftermarket equivalents are readily available from brands like Standard Motor Products (RY-178), Bosch (0332019150), or GP Sorenson (RY-178). Confirm fitment at the parts store.
2. Disconnect Battery: As a safety precaution against short circuits, disconnect the negative battery terminal.
3. Locate and Remove Old Relay: Open the PDC lid. Locate the ASD/Fuel Pump relay socket (as determined earlier). Firmly grasp the faulty relay and pull it straight out of its socket. Avoid excessive twisting force.
4. Install New Relay: Orient the new relay correctly (match the pin configuration visually to the socket). Press it firmly and evenly into the socket until it seats completely and clips in.
5. Reconnect Battery: Reattach the negative battery terminal.
6. Verify Operation: Turn the ignition key to "ON" (do not crank). Listen intently near the fuel tank for the distinct 1-3 second priming sound of the fuel pump. If you hear it, the relay is functioning correctly at this stage. Start the engine normally.

Addressing Related Issues: Fuse, Wiring, and Pump Concerns

A failed relay is common, but other components can mimic its symptoms:

1. Check the Fuel Pump Fuse: The Power Distribution Center (PDC) also houses the fuel pump fuse. Refer to the lid diagram. Identify the fuse (often labeled "FP" or "FUEL PUMP," typically 20 Amp). Pull it out and inspect the metal element inside the plastic casing. A blown fuse shows a visibly broken or melted element. Replace a blown fuse with an identical amp rating fuse. Crucially, a blown fuse often indicates an underlying problem causing it to blow (like a short circuit or pump drawing too much current). Don't ignore this; diagnose further.
2. Inspect Wiring: Visually check the wiring harness near the PDC and running back towards the fuel tank for obvious damage, chafing, corrosion at connectors (especially near the tank), or loose connections. Repair damaged wiring properly (solder and heat shrink, not just electrical tape).
3. Consider the Fuel Pump Itself: If the relay clicks, the fuse is good, and there's power confirmed at the fuel pump connector (usually accessible near or on top of the fuel tank), but the pump doesn't run, then the electric fuel pump motor has likely failed internally and requires tank removal and pump replacement. This is a more complex repair. Listen for the prime sound first – silence points here if relay and fuse are confirmed good. Testing voltage directly at the pump's power wire connector (key on) confirms if power is reaching the pump.

Cost Considerations: Relay Replacement is Affordable

This repair is one of the most cost-effective:

• Fuel Pump Relay Cost: A quality replacement relay (ASD) for the 1992 D150 typically costs $15to$35 USD, readily available at auto parts stores or online.
• Professional Labor Cost: If someone else does the repair, labor is minimal – often billed as 0.3 to 0.5 hours (approx. $35-$75 USD labor). However, given its accessibility (next to the battery), the swap test, and straightforward installation, this is an excellent DIY task.
• Contrast with Fuel Pump Replacement: Replacing the fuel pump itself involves significant labor (dropping the fuel tank, usually 2-4 hours or more) plus the pump cost ($120-$300+), making it a $400-$1000+ repair at a shop. A $20 relay fix saves immense money if it's the culprit.

Preventative Maintenance and Reliability Tips

While relays don't have a scheduled maintenance interval, these practices enhance reliability:

1. Use Quality Replacements: Stick with known reputable brands (Standard Motor Products, Bosch, etc.) for relays. Avoid extremely cheap no-name parts susceptible to premature failure.
2. Check Connections: Periodically ensure the relay is fully seated in its socket within the PDC. Inspect battery terminals and ground connections for corrosion and tightness, as poor voltage supply strains electrical components.
3. Keep PDC Protected: Ensure the PDC lid is securely fastened to protect relays and fuses from water spray and dirt.
4. Carry a Spare: Given the low cost and critical role, carrying a known-good spare ASD/fuel pump relay in your glove box provides cheap insurance against being stranded by a sudden relay failure during a trip. Knowing how to swap it takes minutes.

Conclusion: Solving Fuel Delivery Starts with the Relay

A malfunctioning fuel pump relay is a frequent culprit behind no-start or stall conditions in the 1992 Dodge D150. Its location next to the battery makes diagnosis and replacement accessible for most owners. By understanding its function, recognizing failure symptoms like silence during ignition "ON" or stalling, testing it using a simple swap or multimeter check, and replacing it with a high-quality part, you can quickly restore your truck's fuel delivery. Always verify the related fuse first and consider the fuel pump itself if the relay checks out good. Given its affordability and pivotal role, addressing a suspected fuel pump relay issue is the logical and cost-effective first step in troubleshooting fuel-related problems on this classic truck. The knowledge and confidence to handle this repair yourself saves time and money while keeping your D150 reliably on the road.