Home » Guides » How to Test Ignition Switch with Multimeter?: Step-by-Step Guide

How to Test Ignition Switch with Multimeter?: Step-by-Step Guide

By shafiq usama

How to Test Ignition Switch with Multimeter

As an electrical engineer, I love explaining how things like circuits and electronics work. I write on my blog to share simple explanations, reviews, and useful tips about the latest technology.

Many people ask, how to test ignition switch with multimeter? Read this post to know the most important steps!

It is important to know how to test ignition switch with multimeter; follow these steps. Set your multimeter to the correct range and touch the black probe to a ground point. 

Touch the red probe to each terminal corresponding to switch positions (off, accessory, start). The multimeter should display each position's expected voltage or resistance readings, indicating proper switch functionality.

What is an Ignition Switch?

An ignition switch is a must have component of a vehicle's electrical system. It controls the power supply to the ignition system and other important electrical accessories. It is typically located near the steering column and is operated by inserting and turning the vehicle's key. 

How to Test Ignition Switch with Multimeter

The ignition switch has different positions, including off, accessory (ACC), and on. The switch cuts off power to the ignition system and accessories in the off position.

Read more about How To Test Ac Pressure Switch With A Multimeter?

How to Test Ignition Switch with Multimeter?

There are various steps to do it, here are the steps to know how to test ignition switch with multimeter:

Step 1: Gather the tools and materials

Before testing the ignition switch, gather the following tools and materials: a multimeter, safety gloves, safety goggles, and a wiring diagram or schematic of the ignition system for reference.

Step 2: Safety precautions

Safety is a top priority when working with electrical components or accessories. You should put on your gloves and goggles to protect yourself from harmful potential hazards.

Step 3: Locate the ignition switch

The ignition switch is usually located on or near the steering column, but its exact location can vary depending on the model type of the vehicle.

Step 4: Access the ignition switch

You may need to remove some panels or covers on the steering column to access the ignition switch. Follow the manufacturer's guided instructions or otherwise I would recommend to consult a repair manual for your specific vehicle if you are unsure how to access the ignition switch.

Read more about How To Test A Limit Switch With A Multimeter?

Step 5: Identify the switch terminals

Once you have accessed the ignition switch, you will see multiple electrical terminals or wires connected. The number of terminals can vary depending on the switch's design. 

Refer to the wiring diagram or schematic to identify the specific terminals that correspond to the various functions of the ignition switch, such as the ignition, accessory, and start positions.

Step 6: Set up the multimeter

How to Test Ignition Switch with Multimeter

Turn on your multimeter and set it to the appropriate voltage or resistance range. For most ignition switches, the voltage range is usually DC (Direct Current) 20V.

Step 7: Test the switch in the off position

With the multimeter set up, touch the black probe (negative) to a known ground point, such as the vehicle's metal chassis. Then, touch the red probe (positive) to the terminal that corresponds to the "off" position on the ignition switch. 

The multimeter should display zero voltage or an open circuit, indicating that no power flows through the switch in the off position.

Step 8: Test the switch in other positions

Repeat the previous step for the other positions on the ignition switch. For example, touch the red probe to the terminal corresponding to the "accessory" position and then the "start" position while keeping the black probe connected to the ground. 

The multimeter should display the appropriate voltage or resistance values for each position, indicating that the switch functions correctly.

Step 9: Test for continuity

In addition to testing voltage, you can also test for continuity across the switch terminals. Set your multimeter to the continuity or resistance mode (usually represented by the symbol Ω). 

Touch the black probe to a known ground point and then touch the red probe to each ignition switch terminal, one at a time. The multimeter should emit a continuous beep or display a resistance reading close to zero ohms, indicating continuity through the switch.

Step 10: Interpret the results

You can determine if the ignition switch is functioning correctly based on the voltage and continuity readings obtained during the tests. If the switch does not provide the expected readings or there is no continuity in any of the positions, it may indicate a faulty ignition switch that needs replacing.

Step 11: Reassemble and retest

After completing the tests and confirming the ignition switch's condition, reassemble any removed panels or covers to access it. Once everything is back in place, retest the ignition switch to ensure it functions correctly after the reassembly.

Remember, if you are unsure about any step or lack experience working with automotive electrical systems, I recommend consulting a professional mechanic for assistance or guidance. Now, you know how to test ignition switch with multimeter.

Read more about How to test switch or circuit breaker?

Signs of a Faulty Ignition Switch

The ignition switch controls the vehicle's electrical system. It is responsible for starting the engine and supplying power to various electrical components.

A faulty ignition switch can cause various problems, from difficulty starting the vehicle to intermittent power loss while driving.

Recognizing the signs of a faulty ignition switch can help you address the issue before it leads to a complete breakdown. Here are some common signs to watch out for:

Difficulty Starting the Engine

One of the primary indicators of a faulty ignition switch is difficulty starting the engine. The engine may not crank or start when you turn the start button. This can happen intermittently or consistently. 

If you notice that the engine is slow to start or requires multiple attempts, it could be a sign of a failing ignition switch.

Intermittent Power Loss

A faulty ignition switch can cause intermittent power loss while driving. You may experience a sudden loss of power to the dashboard, lights, or other electrical components while the engine is running. 

It can be dangerous, especially while driving at high speeds or in heavy traffic. If you notice flickering or dimming lights or the radio and other accessories cutting out unexpectedly, it's likely due to a faulty ignition switch.

Stalling

A failing ignition switch can cause your vehicle to stall while driving. The engine may suddenly shut off, leading to power steering and assistance loss. 

If you experience frequent stalling or the engine dies unexpectedly, have your ignition switch checked by a qualified mechanic.

Problems with Electrical Accessories

Another sign of a faulty ignition switch is problems with electrical accessories. Your vehicle's electrical components, such as power windows, door locks, and windshield wipers, may not work properly or stop functioning altogether. Sometimes, they work intermittently or only when the key is held in a particular position.

Key Getting Stuck

If you're having trouble removing the key from the ignition, it could be due to a faulty ignition switch. The switch may not release the key properly, making removing it difficult or impossible. 

It can be inconvenient, especially if you turn off the engine quickly or leave the vehicle unattended.

Engine Fails to Shut Off

On the other hand, a faulty ignition switch may prevent the engine from shutting off completely. When you turn the key to the off position, the engine may continue to run or sputter before finally stopping. This can pose a safety hazard and potentially cause damage to the engine if left unresolved.

FAQs

How do you check for a bad ignition switch?

You can perform these few tests to check for a bad ignition switch. Start by using a multimeter to measure voltage and continuity. Set your multimeter and check the voltage at switch positions (off, accessory, start). If the readings are significantly different from the expected values or there is no voltage present, it may indicate a faulty ignition switch.

What is the voltage of the ignition switch?

The voltage of an ignition switch can vary depending on the specific vehicle and its electrical system. In most cases, when the ignition switch is in the on position, the voltage should be within the range of 12 to 14 volts. This voltage level is typically necessary to provide sufficient power to the ignition system and other vehicle electrical components.

How do you check for a spark in the ignition?

You can follow the steps to check for a spark in the ignition system. Start by removing a spark plug wire from the spark plug. Insert a spark tester into the end of the wire, ensuring a good connection. Next, have someone crank the engine while you observe the spark tester. If you see a strong, visible spark jumping across the gap of the tester, it indicates that the ignition system is producing a spark.

Conclusion

It is important to know how to test ignition switch with multimeter. By following the steps above, which include setting up the multimeter, identifying the switch terminals, and testing for voltage and continuity in each switch position, you can determine the functionality of the ignition switch. 

Remember to prioritize safety by wearing protective gear and consulting professional assistance. Properly diagnosing the ignition switch helps ensure the efficient operation of your vehicle's electrical system and ignition functions.