<em>Nissan Sunny FB15</em>fuel pump relay: exact location, diagram and fault diagnosis

Nissan Sunny FB15 (also known as B15 or N16 depending on the market) is a legendary Japanese sedan that is still used in many countries due to its reliability. However, even such time-tested cars have typical malfunctions. One of them is a failure of the **fuel pump relay**, which can manifest itself as a complete failure to start the engine, or periodic “twitching” of the engine while driving.

If your Sunny FB15 suddenly stopped starting, but the starter turns, and the characteristic buzzing of the fuel pump is not heard in the cabin - the problem with a 90% probability lies in the relay or fuse. In this article we will not only show **where the fuel pump relay is located** on Nissan Sunny FB15, but we will also teach you how to diagnose it yourself, without resorting to the services of a car service. We’ll also look at common myths, for example, why replacing the relay with a similar one from Nissan Almera N16 may cause a short circuit.

1. Signs of a malfunctioning fuel pump relay on Nissan Sunny FB15

The fuel pump relay is an electromechanical device that controls the voltage supply to the fuel pump. When it fails, symptoms can range from subtle to severe. Here are the key signs that should alert you:

• 🚗 The engine does not start, although the starter turns. At the same time, there is no sound of the fuel pump operating (usually it is heard in the cabin when the ignition is turned on).
• ⚡ The car starts only after several attempts - this indicates “sticking” of the relay contacts.
• 🔥 The engine stalls while driving, especially during sudden acceleration or at high speeds. This is due to the relay overheating.
• ⚠️ The dashboard lights up CHECK ENGINEand the scanner shows an error P0190 (fuel pressure sensor circuit malfunction).

It is important to distinguish problems with the relay from malfunctions of the fuel pump or fuse itself. For example, if the pump hums when you turn on the ignition, but the engine does not start, the fault is most likely not the relay, but clogged fuel filter or a failed pump.

⚠️ Attention: If after replacing the relay the fuel pump starts working, but after 5-10 minutes it turns off again, the problem may lie in oxidized contacts of the fuse box or damaged wiring. In this case, a complete diagnosis of the electrical circuit is required.

2. Where is the fuel pump relay located on Nissan Sunny FB15: step by step instructions with photos

B Nissan Sunny FB15 The fuel pump relay is located in fuse and relay box, which is located inside the car, under the instrument panel on the driver's side. The exact location depends on the year of manufacture and configuration, but in 95% of cases it is:

1. Open the driver's door and sit in the seat.
2. Lower the steering column to its lowest position for convenience.
3. Under the dashboard, to the left of the steering column, locate the plastic fuse box cover. It is secured with two latches.
4. Carefully pry the cover with a screwdriver or flat object and remove it.

A block with fuses and relays will open in front of you. Fuel pump relay FB15 usually found in one of the following locations:

• 🔧 B top row, third relay on the right (there may be a designation on the block cover FUEL PUMP).
• 🔧 B bottom row, the first relay on the left (if the block is divided into two sections).

To avoid mistakes, check the back of the block cover - there should be a diagram with symbols there. If there is no diagram or it has been erased, use our checklist to search:

The photo below shows a typical fuse box Nissan Sunny FB15 (1999–2004). The fuel pump relay is circled in red:

The relay is standard size 12V 30A and labeling TYCO or Panasonic on the body. If there are no markings on your unit, you can temporarily swap the relay with another one (for example, with a fan relay) - if after this the fuel pump starts working, you have found the culprit.

3. Connection diagram for the fuel pump relay: pinout and contact assignments

Fuel pump relay Nissan Sunny FB15 has a standard pinout with 4 contacts, but their purpose often raises questions. Below is a diagram and explanation for each pin:

Contact number	Purpose	Wire Color (Typical)	Voltage (V)
85	Control minus (from the ECU)	Black/white	0 (with ignition off), 12 (with activation)
86	Constant plus (from battery via fuse)	Red/yellow	12 (permanent)
87	Output to fuel pump	Grey/green	12 (when the relay is triggered)
30	General plus (from battery)	Red	12 (permanent)

To test the relay you will need multimeter or control lamp. Diagnostic algorithm:

1. Turn on the ignition (without starting the engine).
2. Measure the voltage between the contacts 86 And 85: must be 12V.
3. If there is no voltage, the problem is in the control circuit (ECU or wiring).
4. If there is voltage, but the relay does not click, it is faulty.

You can also check the resistance of the relay winding: between the contacts 85 And 86 it must be within 50–120 Ohm. If the multimeter shows an open or short circuit, the relay must be replaced.

4. Which fuse is responsible for the fuel pump on Nissan Sunny FB15

The fuel pump relay is paired with a fuse that protects the circuit from short circuits. On Sunny FB15 this is a fuse rated 15A, located in the same block as the relay. Its designation:

• 🔥 FUEL PUMP (on the block cover).
• 🔥 EFI (on some versions).
• 🔥 Fuse number 20 or 22 (see diagram on the cover).

If the fuse is blown, do not rush to replace it - first find the cause. Common reasons:

• 🔌 Short circuit in the fuel pump wiring (for example, due to a frayed wire).
• 💧 Moisture getting into the fuse box (especially important after washing or rain).
• 🔧 Faulty fuel pump that consumes current above normal.

⚠️ Attention: If the new fuse burns out immediately after installation - strictly prohibited install a fuse of a higher rating (for example, 20A instead of 15A). This may cause the wiring to catch fire!

5. Which fuel pump relay is suitable for Nissan Sunny FB15: originals and analogues

Original fuel pump relay for Nissan Sunny FB15 has an article number 25230-4M000 or 25230-4M005 (depending on the year). However, it can be replaced with analogues from other manufacturers. The main thing is to follow the parameters:

• 🔌 Rated voltage: 12V.
• 🔌 Switching current: no less 30A.
• 🔌 Contact type: 4-pin (standard for Japanese cars).

Suitable analogues:

Manufacturer	Article	Notes
TYCO	V23134-C1018-A402	Direct analogue, used in Nissan Almera N16 And Primera P12.
Panasonic	AZ2500-1C02	High quality, but more expensive than the original.
Bosch	0 332 019 150	Universal relay, suitable for most Japanese cars.
Hella	4RA 003 507-331	German quality, but pinout may vary (check before installation).

Important: do not use relays from Nissan Almera N16 without verification! Despite the external similarity, in some versions Almera the relay has a different connection diagram (contacts 87 And 30 may be mixed up), which will lead to a short circuit.

What happens if you install an incompatible relay?

If you install a relay with a different pinout (for example, from European cars), two scenarios are possible:

1. The fuel pump will not receive voltage and the car will not start.

2. A short circuit will occur, which will damage the fuse or even the ECU.

Always check the pinout before replacing!

6. Step-by-step replacement of the fuel pump relay with Nissan Sunny FB15

Replacing the relay is a simple procedure that takes no more than 5 minutes. You will need:

• 🔧 New relay (trusted manufacturer).
• 🔧 Flat screwdriver (for removing the block cover).
• 🔧 Flashlight (for convenience).

Replacement algorithm:

1. Turn off the ignition and remove the negative terminal from the battery (for safety).
2. Remove the fuse box cover (as described in section 2).
3. Locate the fuel pump relay (see diagram or temporarily swap it with another relay to test).
4. Gently pull the relay up; it should come out of the connector without effort.
5. Install the new relay, making sure the contacts match.
6. Replace the unit cover and connect the battery.
7. Check the operation of the fuel pump: when you turn on the ignition, you should hear the sound of its operation (a buzzing sound in the rear seat area).

⚠️ Attention: If the fuel pump does not turn on after replacing the relay, check fuse And mass on the body (often oxidizes under the rear seat). Also make sure that the relay is receiving 12V to contact 86.

- Faulty fuel pump;

- Broken wiring between the relay and the pump;

- Faulty ECU (rare, but possible).-->

7. Frequent mistakes during diagnostics and repairs

Even experienced car owners sometimes make mistakes when working with the fuel pump relay. Here are the most common:

• 🔧 Replacing the relay without checking the fuse. The fuse may be blown, but the relay may be fine.
• 🔧 Using relays from other cars without testing. For example, a relay from VAZ or Toyota may not be suitable for current or pinout.
• 🔧 Ignoring oxidized contacts. Even a new relay will not work if the connector in the fuse box is coated with oxide.
• 🔧 Checking the relay without taking into account temperature. The relay may work normally when cold, but fail when warmed up (for example, after 20 minutes of driving).

To avoid these errors, follow our algorithm:

If after all the checks the problem remains, the fuel pump itself may be faulty or there is a break in the wiring. In this case, a more in-depth diagnosis will be required using error scanner or checking the voltage at the pump connector (under the rear seat).

Frequently asked questions (FAQ)

Is it possible to drive with a faulty fuel pump relay?

No, it's dangerous. If the relay is faulty, the fuel pump may turn off while driving, which will lead to the engine stopping at an unpredictable moment (for example, at an intersection or highway). In addition, unstable pump operation can cause fuel system overheating and even a fire.

Why does a new relay burn out quickly?

If a new relay fails within a short time, the cause is usually:

• Short circuit in the fuel pump wiring;
• Faulty fuel pump (consumes current higher than normal);
• Poor ground contact (relay heats up due to increased load).

Check the circuit with a multimeter and make sure that the pump current consumption does not exceed 10A.

Can the fuel pump relay be repaired or is it just a replacement?

Theoretically, the relay can be disassembled and the contacts cleaned, but in practice this is inappropriate. The cost of a new relay is only 300–800 rubles, and after repair it will not last long due to wear of internal parts. The exception is if the relay is simply oxidized on the outside (then it is enough to clean the contacts with alcohol).

Where else could the fuel pump relay be if it's not in the fuse box?

In rare cases (for example, after tuning or replacing the wiring), the fuel pump relay can be moved to another location:

• Under the hood, in the additional relay box;
• Behind the glove compartment (on some export versions);
• In the trunk, next to the fuel pump (extremely rare).

If you do not find the relay in the standard location, check for additional units or contact an electrician.

What other relays can affect engine starting?

If the problem is not with the fuel pump relay, check:

• 🔧 ECU relay (responsible for powering the control unit);
• 🔧 Main relay relay (on some versions);
• 🔧 Ignition relay (if power does not come to the coils).

Also make sure that immobilizer does not block startup (on some Sunny FB15 with an alarm it can turn off the fuel pump).