How To Test A Bad Starter Relay? - ALION

1. Introduction

Ever found yourself stuck with a car that just won’t start? If you’re considering whether to repair or replace a starter relay, you’re not alone.

A starter relay can fail due to several reasons, such as electrical overload, corrosion, or simply wear and tear over time. These issues can prevent your vehicle from starting, leaving you frustrated and stranded.

But don’t worry—this article is here to guide you through the process of testing a starter relay. By following our step-by-step instructions, you’ll gain the knowledge needed to diagnose the problem and decide on the best course of action.

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2. Understanding Relays

2.1 What is a Relay?

A relay is an electrically operated switch that can be used to control a circuit with a low-power signal. It consists of an electromagnet, a set of contacts, and a coil. When a current flows through the coil, the electromagnet is activated, which in turn opens or closes the contacts, allowing or blocking the flow of current through the circuit.

Relays are commonly used in a wide range of applications, including automotive, industrial, and consumer electronics. This ability to control high-power circuits with low-power signals makes relays indispensable in many electrical systems.

2.2 Types of Relays

• Electromechanical Relays: Use a physical mechanism to open and close contacts, making them reliable for many traditional applications.
• Solid-State Relays: Utilize semiconductor devices to switch the circuit, offering faster switching times and longer life spans due to the absence of moving parts.
• Hybrid Relays: Combine the benefits of both electromechanical and solid-state relays, providing a balance of durability and performance.

The choice of relay depends on factors such as the required switching speed, load capacity, and environmental conditions.

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3. Starting relay function

Between the vehicle’s battery and the starter motor, the starter relay acts as a circuit completer or circuit breaker.

It helps to increase the battery’s current so that less current needs to be ignited. According to the description, this is a switch between the start solenoid and the start motor.

When you turn the ignition key or press the car’s start button, a large current is generated. The starter motor requires considerable current, and the ignition switch cannot be controlled. If there is no relay, it will burn out. If the starting relay fails, the vehicle may not start.

As we will see later, there are many reasons why this component may fail. They also require various treatments according to the nature and severity of the hazard. Some can be repaired, and some require the installation of new relays.

4. How does Starter Relay work with others?

The starter relay is a key part of your car’s starting system. It works with the ignition switch, battery, and starter motor to get the engine going. When you turn the key to “start,” it sends a signal to the starter relay. The relay then turns on the starter motor. This motor spins the engine, and once the engine runs, the relay shuts the starter motor off.

The starter relay also teams up with the FUSE BOX to keep the electrical system safe. It helps protect against overloads and short circuits. This makes sure all the electrical parts in your car stay working right and don’t get damaged.

5. Starting relay position

Where to find the start relay changes based on what car you have. It might be in the power box (also called the fuse box), under the dash panel, or near the right fender. In most cars, you’ll find it under the hood in a big box with a black cover. This is where all the car fuses and relays are kept. People call this the fuse box too. This box is usually on the driver’s side of the car.

Wires stick out from the relay. But watch out – many other relays in cars look alike. Finding the fuse box with the starter relay under the dashboard can be HARD or even tough to take out. It might be easier to spot the starting relay if it’s on the fender wall. These relays are usually shaped like cylinders and you can tell which they are by their mounting posts and wires. If you’re not sure which one starts your car, check your service manual.

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6. Symptoms of starter relay failure

The starter relay, like other mechanical and electronic components in your car, will show signs of failure before it finally stops.

Some signs of damaged or worn starter relays are listed below.

If you see these warning signs, please make an appointment with a local ase-certified mechanic to conduct a thorough inspection of your car, as these symptoms may indicate a problem with other components.

When diagnosing a faulty relay, it is important to check the continuity and resistance across each pin to ensure proper functionality.

When we turn off the ignition switch, both the starting solenoid and the motor should stop working.

When the starter relay doesn’t operate in this order, the engine won’t start. It is likely that the main contacts are already welded together, in the closed position.

If this happens, the starter relay will be trapped in the start position, causing damage to the starter, circuit, relay and drive flywheel, if not dealt with immediately.

1) The vehicle cannot be started

The failure of a car to start is one of the most obvious signs of a car breakdown.

Although many potential failures may prevent the car from starting, the failure of the starting relay is often the source of the problem. To understand why, we must first understand the function of the starter relay better.

When you turn the ignition key, your battery is shaken, releasing a burst of electrical energy. The starter motor is triggered by this energy and turns your engine.

A starting relay completes the circuit before reaching the starter motor, but also increases battery current when it passes through it.

A defective starter relay will prevent your battery from delivering electrical signal to your starter motor. Therefore, no matter how many times you turn the key, your engine will not start.

When you turn the key, if the circuit is not broken, you may hear a click.

In either case, you should get professional help to evaluate the symptoms and accurately diagnose the cause.

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2)The start relay remains open after the engine is started

The starting relay and the starting solenoid send current to the ignition switch when you turn on your ignition. The starter motor rotates the flexible board to start the engine, and the solenoid supplies power to the flexible board.

When we turn off the ignition switch, both the starting solenoid and the motor should stop working.

The main contacts of the starter relay are probably already welded together, in the closed position, if it does not operate in this order, the relay keeps the engine started.

If this happens, the starter relay will be trapped in the start position, causing damage to the starter, circuit, relay and drive flywheel, if not dealt with immediately.

It usually happens when the relay touches anything or is exposed to a lot of electricity. Because this problem may damage the entire boot system, it must be diagnosed and dealt with immediately.

3) The starter makes a clicking sound

Relays usually operate on an all-or-nothing basis. It either sends the entire current, or it sends nothing.

However, when the starter relay is destroyed, only a part of the signal can be sent.

The starter relay makes a clicking sound, but the engine does not rotate, which indicates that the starter motor is not receiving enough current from the relay.

This may also be a sign of low or exhausted battery power. Only when it transmits enough current to the starter, the relay starts to work.

Smaller power may damage the entire starting device or cause the vehicle to fail to start, accompanied by annoying clicking sound.

Both of these conditions may be caused by corroded or aging relays with damaged contacts.

Cleaning the contact points to ensure the correct flow or replacing the old relay are the only two options for repair.

Scrape the corroded surface of the relay with sandpaper or a gravel scraper.

You can replace the relay to get a larger output, or you can contact a professional mechanic.

4)The vehicle starts intermittently

When the starter relay is working, it transmits power to the starter every time it is turned on.

However, debris, dirt and high temperatures can contaminate this ingredient.

Corrosion and residues in the circuit restrict the flow of current.

Due to these conditions, the starting relay may be forced to work intermittently.

The starter relay is the basic component of the ignition system and has very few moving components, which is why it rarely fails.

However, when it happens, it is due to conductivity issues. If the relay is not malfunctioning, there may be a damaged or corroded wire connection under the hood.

7. How to test the starting relay?

Safety Precautions

When working with electrical systems, it’s crucial to take safety precautions to avoid electrical shock, injury, or damage to the equipment. Here are some safety precautions to take when testing a relay:

• Make sure the power source is disconnected before starting the test.
• Use a digital multimeter to measure voltage, current, and resistance.
• Set the multimeter to the correct range and function (e.g., ohms setting for measuring resistance).
• Use insulated tools and equipment to avoid electrical shock.
• Avoid touching electrical components or wires with your bare hands.
• Keep the work area clean and well-lit to avoid accidents.

By following these safety precautions, you can ensure a safe and successful relay testing process.

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Material:

1. Fully charged battery
2. A portable jumper cable manufacturing technology
3. Baking soda, water and wire brush

Tool:

Safety glasses and gloves

Step 1

Ensure that the car is parked safely and the transmission is in neutral or parked state. When working under the hood, you don’t want the vehicle to move forward accidentally.

Step 2

Before testing, prepare a fully charged battery and a portable jumper. Or, you can check your car battery to make sure it is fully charged and not the source of your problem. During the whole test, please pay attention to how to connect the jumper cable to the battery terminal.

Step 3

Check the connection terminals on the battery and starter.

Make sure they are free of rust, oil, dust and debris. Before cleaning corroded terminals, disconnect the negative battery cable and set it aside.

Remove the battery positive cable from the battery and set it aside.

Take care to prevent the cables from accidentally contacting the battery terminals.

Use baking soda, water and a wire brush to clean the rusty terminals. If necessary, clean the starter terminal. If possible, disconnect the battery cable.

Step 4

The cable from the starting solenoid to the starting relay should be followed. There are four terminals on the relay.

Two smaller wires are used to “turn on” the relay and come from the critical switching circuit.

Two larger wires connect from the battery to the starter, carrying the battery voltage.

Remove the wires from the starter relay and mark the two smaller wires so that they can be reconnected appropriately.

Connect one end of the jumper wire to the chassis ground. Terminal 86 should be connected to the other end.

Step 5

Connect a jumper wire to the positive terminal of the battery. Since the connection between the battery and the starter has been cut off, the jumper can be connected for a short time.

A digital voltmeter should be used to measure the resistance between terminals 30 and 87.

Its resistance should be less than 1 ohm. If the resistance is greater than 1 ohm, the relay does not work. The relay needs to be replaced.

To measure resistance and continuity, follow these steps:

1. Set the Multimeter: Set your digital multimeter to the ohms setting.
2. Measure Coil Resistance: Measure the resistance between the relay’s coil pins, usually labeled 85 and 86. The resistance should be within the specified range for your relay.
3. Check Contact Resistance: Measure the resistance between the relay’s normally open (NO) and normally closed (NC) contacts. This will help you determine if the contacts are functioning correctly.
4. Test Continuity: Use the multimeter’s continuity function to check for continuity between the relay’s pins and contacts. This ensures there are no breaks in the circuit.

8. How to replace the starting relay using a digital multimeter?

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Install a jumper wire between the positive and negative terminals of the battery.

You can now leave the jumper connection for a short time now that the battery connection to the starter has been disconnected.

Between terminals 30 and 87, measure the resistance with a digital voltmeter.

A resistance of less than 1 ohm is required. If the resistance is greater than 1 ohm, the start relay will not work. The relay must be replaced.

Material preparation: safety glasses, safety thread

Tools: pliers, wrenches, wires

1) How to disassemble the starting relay correctly?

You can open the hood and disconnect the negative connection of the battery if it is a fuse box to start the relay. Next find the fuse box. Usually a box with a black lid.

If you cannot find the starting relay, please use the instructions. Determine the position of the starting relay according to the information on the fuse box cover. Then, remove the starting relay.

If it is a mud wall relay, follow the method below to get rid of it. First, use a wrench to remove the battery terminals.

Second, disconnect the leads connected to the relay terminals. Use a wrench to remove the bolts connecting the wires to the relay column.

Two large and two small pillars serve as connection points. Third, remove the relay from the mudguard by unscrewing the mounting screws.

2) How to install the starting relay

The process of installing the fuse box starter relay is simple. There are no nuts or screws to tighten, and no need to worry about torque.

Bring your new relay. Push the relay in slowly and slowly until it reaches the end of the valve seat, matching the pins with the slots in the fuse box. Close the lid and reconnect the battery terminals that were disconnected when the old relay was removed.

Follow the steps below to install the start relay on the mudguard.

Place the relay on the mounting surface and fix it there. By inserting and tightening the screws, attach the relay to the fender wall. Install the starter circuit and battery wires, taking care not to connect the wrong wires to the wrong poles. Reconnect the battery cable that was disconnected before.

After the installation is complete, test and start the system. There should be no difficulty in starting this car. If this is the case, check the wires and connections. Make sure the connection is firm and the fender wall start relay is wired correctly. If you can’t figure out the problem, you need to look at the other components of the boot system. Or, ask a mechanic to check the car.

3) Wiring of starting relay

The wire is installed on the connecting post of the starter relay mounted on the fender. Usually, these leads are connected during the installation process. The relay must be wired correctly in order to work safely. This picture shows how to connect a four-connection starter relay

Step1

Disconnect the positive terminal of the battery. To avoid accidents, please fix the bare end. You can do it with tape.

Step 2

Thick start solenoid cables can be found here. Connect it to a large stud or upright of the relay. Tighten the mounting bolts to secure the connection. Because the starter relay has no polarity, which large one do you connect the wire to

Step 3

Prepare ignition switch wiring. They are usually thinner than starting cables because they only carry a limited amount of current. One of the two wires should be connected to a small stud on the relay. Connect the remaining small post to another wire.

In some relay races there is only one small post. If this is the case, connect the ignition wire to the mounting screw or bolt. Any other part of a relay housing can also be connected to it. This is because a small terminal of the relay is usually grounded.

Fourth

Connect the remaining thick wires to a single huge stud or pole. This is the cable connecting the positive terminal of the battery.

Finally, turn on the ignition switch to test the relay wire. There should be no difficulty in starting the engine and cranking. If it still doesn’t work, check the wires again to make sure that each cable is connected to the correct terminal and securely.

9. Conclusion

In the vehicle that needs to start the relay, it is very important to check whether the start relay is normal. This is a standard aspect of vehicle daily maintenance. It can save you from getting into trouble and being trapped in remote places. The first step is to understand how relays work and how to identify failed relays early.

We hope this starter relay guide has provided you with enough knowledge to help you solve the starter relay problem that caused the car’s starting problem. You can now recognize the signs of starting relay failure and how to test it.

10. Frequently asked questions about starting relay

1) Can you fix the starting relay?

If the starter relay fails, you will not be able to start the engine. Damage to the starter relay is usually caused by a short circuit due to a poor power connection on the starter. Relays that are not working cannot be removed for repair; in order to start the engine, you must install a new one.

2) Is it easy to replace the starting relay?

With the right tool and knowledge of what wire to connect to which terminal, the process of replacing the starter relay should be easy. Fuse box relays are easier. It usually involves unplugging the old relay and then plugging in the new relay.

3) What is the cost of starting relay replacement?

Excluding the cost of starting the relay, it is expected to pay about $30. Adding the cost of purchasing the components, the total cost of installing a new relay is approximately $50.

4)How long does the starting relay last?

Normally, the starting relay will last more than 100 miles. These parts are durable, with only a few moving parts, so wear is minimal. The biggest threat to the life of the starting relay is usually the contact burnout.

5)Is the starting relay the same as the starting solenoid?

In most cases, a real starter relay is a small black cube plugged into the electrical fuse/relay box in the engine room, and the starter solenoid (in most cases) is directly connected to the starter on the engine (although it Sometimes located elsewhere in the engine room).

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